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Sample records for alloy c-22 induced

  1. Passivity of alloy C-22 in NaCl solutions

    International Nuclear Information System (INIS)

    Alloy C-22 has been proposed as the corrosion resistant barrier of high-level waste nuclear containers. This alloy must be resistant to corrosion in multi-ionic solutions for a period of time as long as 10,000 years. The aim of the present work was to study the corrosion behavior of alloy C-22 in NaCl solutions. General and crevice corrosion were studied by means of electrochemical techniques. Open circuit potential was measured over the time, electrochemical impedance spectroscopy (EIS) measurements were carried out at open circuit and passivity potentials, as well as cyclic potentiodynamic polarization curves. Corrosion rates obtained by EIS measurements were acceptable for a waste nuclear container (P) values increased with open circuit potential and polarization time at constant potential. This was attributed to an increase in oxide film thickness and its aging respectively. The passive oxide form on alloy C-22 at the studied conditions presented a n-type semiconductor behavior in the passive potential range. Repassivation potential values (ER1) were determined for alloy C-22 at the studied conditions using PCA probes. (author)

  2. Study crevice corrosion alloys C-22 and 625 by electrochemical noise

    International Nuclear Information System (INIS)

    C-22 and 625 alloys are two of the Ni –Cr-Mo alloys considered as candidate materials to form the corrosion resistance engineered barriers for nuclear waste repositories. The corrosion resistance of these alloys is remarkable in a wide variety of environments. Despite of their resistance these alloys are susceptible to crevice corrosion in a certain aggressive environments. This work presents the use of electrochemical noise technique to study crevice corrosion susceptibility of alloys C-22 and 625 in 1M NaCl acidic solutions at 60ºC and 90ºC. Asymmetrical electrodes and a complementary platinum electrode were used to assess the influence of cathodic reaction in crevice process. The obtained records were analyzed directly and through statistical parameters. The potential drop and the simultaneous increment of the current records indicated the occurrence of crevice corrosion. The alternative use of a platinum electrode resulted in higher currents and higher potentials and reduced the induction time to crevice formation. The reason for this behavior is that platinum surface allows faster cathodic reactions than C-22 and 625 alloys. The standard deviation of the current records was responsive to the crevice corrosion intensity. C-22 alloy had better crevice corrosion performance than 625 alloy. (author)

  3. Corrosion of alloy C-22 in organic acid solutions

    International Nuclear Information System (INIS)

    Electrochemical studies such as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 (N06022) in 1M NaCl solutions at various pH values from acidic to neutral at 90 C degrees. All the tested material was wrought Mill Annealed (MA). Tests were also performed in NaCl solutions containing weak organic acids such as oxalic, acetic, citric and picric acids. Results show that the corrosion rate of Alloy 22 was significantly higher in solutions containing oxalic acid than in solutions of pure NaCl at the same pH. Citric and Picric acids showed a slightly higher corrosion rate, and Acetic acid maintained the corrosion rate of pure chloride solutions at the same pH. Organic acids revealed to be weak inhibitors for crevice corrosion. Higher concentration ratios, compared to nitrate ions, were needed to completely inhibit crevice corrosion in chloride solutions. Results are discussed considering acid dissociation constants, buffer capacity and complex formation constants of the different weak acids. (author)

  4. A comparative study on the high temperature corrosion of TP347H stainless steel, C22 alloy and laser-cladding C22 coating in molten chloride salts

    International Nuclear Information System (INIS)

    Highlights: • Two KCl and NaCl mixtures simulated molten salt corrosion of biomasses combustion. • The corrosivity of forestry and agricultural biomasses was comparatively studied. • Corrosion of TP347H, C22 alloy and C22 coating was carried out at 450–750 °C. • Laser-cladding C22 coating exhibited least performance degradation. • Microstructures, compositions and corrosion mechanisms were strongly interrelated. - Abstract: Isothermal corrosion of TP347H (A1), C22 alloy (A2) and laser-cladding C22 coating (A3) was evaluated by mass loss measurements in molten alkali chloride salts at 450–750 °C. Corrosion mechanisms were characterised by scanning electron microscopy, optical microscopy and X-ray diffraction. A3 exhibited superior corrosion resistance, followed by A2, which results from alloying elements, refined microstructure and Cr–O (CrOx), Co(Fe, Cr)2O4 in the corrosion scale. Severe intergranular corrosion caused failure of A1, slight intergranular corrosion happened in A2 but none in A3. Fe-rich oxides were main products of A1 while NiO of A2 and A3 with Cr2O3 and Mo-containing compositions

  5. Effect of fluorides and chlorides upon corrosion behavior of alloy C-22

    International Nuclear Information System (INIS)

    Alloy C-22 is one of the candidates to fabricate the external wall of the high level nuclear waste containers. These packages are designed to maintain isolation of the waste for a minimum of 10,000 years. During this period they must resist atmospheric corrosion. Electrochemical techniques such as cyclic potentiodynamic polarization, electrochemical impedance spectroscopy and variation of corrosion potential in time and non-electrochemical techniques such as X-ray fluorescence (XRF) and microscopy were applied to determine the effect of fluorides and chlorides upon general and localized corrosion of different microstructures of alloy C-22. The corrosion rates obtained were about 0.1 μm/year. Crevice corrosion was detected only in those solutions where chlorides ions were present. Fluoride ions affected the passivity and trans passivity behavior of the alloy. They produced higher current densities than chlorides in both ranges. There were no differences in corrosion behavior of the different microstructures. Mixtures of chlorides and fluorides seem to be more detrimental than the separated ions regarding to localized corrosion and trans passivity. (author)

  6. Influence of Thermal Aging on the Mechanical and Corrosion Properties of C-22 Alloy Welds

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-06-15

    The phase stability of C-22 alloy (UNS No. N06022) gas tungsten arc welds was studied by aging samples at 427, 482, 538, 593, 649, 704, and 760 C for times up to 40,000 hours. The tensile properties and the Charpy impact toughness of these samples were measured in the as-welded condition as well as after aging. The corrosion resistance was measured using standard immersion tests in acidic ferric sulfate (ASTM G 28 A) and 2.5% hydrochloric acid solutions at the boiling point. The microstructures of weld samples were examined using scanning electron microscopy (SEM). One weld sample (aged 40,000 hours at 427 C) was examined using transmission electron microscopy (TEM). The structure of the unaged welds was dendritic with tetrahedrally close-packed (TCP) phase particles in the interdendritic regions. Long-range order was seen in the weld aged at 427 C for 40,000 hours and was assumed to also occur in other welds aged below approximately 600 C. At temperatures above about 600 C, TCP phase nucleation and growth of existing particles occurred. This precipitation occurred near the original particles presumably in regions of the highest molybdenum (Mo) segregation. Lower temperatures had little or no effect on the morphology of TCP phases. The C-22 weld samples were approximately 25% stronger but 30-40% less ductile than the base metal. Strengthening of the weld during aging occurred significantly only at 593 C for the aging times investigated. Because strengthening was not seen at higher temperatures, it was assumed to be due to ordering which has been seen in C-22 base metal at this temperature. A small amount of strengthening was seen at 427 C after 40,000 hours where ordering was just beginning. The Charpy impact toughness was reduced dramatically with aging. The time at which this reduction occurred decreased as aging temperature increased suggesting that the reduced ductility is due to the presence and growth of the brittle TCP phases. The corrosion rate of weld

  7. APT characterization of a high strength corrosion-resistant Ni-Cr-Mo HastelloyR C-22HSTM alloy

    International Nuclear Information System (INIS)

    Full text: The versatile C-type Ni-Cr-Mo alloys are well known for their corrosion resistance. These alloys have been used for many years in a wide variety of applications such as heat exchangers, scrubbers, reaction vessels, etc. as they exhibit significantly higher strength than most stainless steels. The strength of these alloys may be further increased by cold working. However, this mechanical processing approach limits the size and geometry of the final components. In addition, the high strength is lost in welds and associated heat affective zones. A new high strength corrosion-resistant alloy Ni-21% Cr-17% Mo, HASTELLOY C-22HS, has recently been developed to overcome these problems. This general purpose corrosion-resistant alloy may be used at temperatures of up to at least 600oC. Potential applications for this corrosion resistant high strength alloy include shafting, agitators, fan blades, hubs, springs, fasteners, valves, dies, rings and gaskets. The composition of the HASTELLOY C-22HS alloy used in this study was Ni, 20.6 wt. % Cr, 16.6% Mo, 1.1% Fe, 0.33% Al, 0.29% Mn, 0.11% Nb, 0.004% C and 0.004% B. The microstructure of the HASTELLOY C-22HS alloy was characterized in the age hardened condition - 16 h at 705oC, furnace cooled to 605oC, 32 h at 605oC and air cooled. The microstructure of this age hardened alloy was characterized with the Oak Ridge National Laboratory local electrode atom probe. The corrosion resistance of this alloy in HCl at 52oC and H2SO4 at 79oC was found to be similar to N06022 alloy and better than N07725 alloy. The yield strength of this alloy and N06022 were similar in the mill annealed condition. After the age hardening treatment, the 0.2% yield strength of the HASTELLOY C-22HS alloy increased from 222 to 542 MPa. The tensile elongation and the reduction in area of the age hardened alloy were 40% and 50%, respectively at room temperature and 48% and 66%, respectively at 595oC. Atom probe tomography of the HASTELLOY C-22HS alloy

  8. Effect of thermal aging on corrosion resistance of C-22 alloy in chloride solutions

    International Nuclear Information System (INIS)

    Alloy 22 (N06022) belongs to the Ni-Cr-Mo family and it is highly resistant to localized corrosion. The anodic behavior of mill annealed (MA) and thermally aged (10 hours at 760 C degrees) Alloy 22 was studied in chloride solutions with different pH values at 90 C degrees. Thermal aging leads to a microstructure of full grain boundary precipitation of topologically closed packed (TCP) phases. Electrochemical tests included monitoring of open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. Assessment of general and localized (crevice) corrosion was performed. Re passivation potentials were obtained from cyclic potentiodynamic polarization tests. Results indicate that MA and TCP material show similar general corrosion rates and crevice corrosion resistance in the tested environments. MA and TCP specimens suffered general corrosion in an active state when tested in low pH chloride solutions. The grain structure of the alloy was revealed for MA material, while TCP material suffered a preferential attack at grain boundaries. (author)

  9. Distribution of soluble and precipitated iron and chromium products generated by anodic dissolution of 316L stainless steel and alloy C-22: final report

    Energy Technology Data Exchange (ETDEWEB)

    Estill, J; Farmer, J; Gordon, S; King, K; Logotetta, L; Silberman, D

    1999-08-11

    At near neutral pH and at applied potentials above the threshold potential for localized breakdown of the passive film, virtually all of the dissolved chromium appeared to be in the hexavalent oxidation state (Cr(VI)). In acidic environments, such as crevice solutions formed during the crevice corrosion of 316L and C-22 samples in 4 M NaCl, virtually all of the dissolved chromium appeared to be in the trivalent oxidation state (Cr(III)). These general observations appear to be consistent with the Pourbaix diagram for chromium (Pourbaix 1974), pp. 307-321. At high pH and high anodic polarization (pH {approximately} 8 and 800 mV vs. SHE), the predominate species is believed to be the soluble chromate anion (CrO{sub 4}{sup 2{minus}}). At the same pH, but lower polarization (pH {approximately} 8 and 0 mV vs. SHE), the predominate species are believed to be precipitates such as trivalent Cr(OH){sub 3} {center_dot} n(H{sub 2}O) and hexavalent Cr{sub 2}O{sub 3}. In acidified environments such as those found in crevices (pH < 3), soluble Cr{sup 3+} is expected to form over a wide range of potential extending from 400 mV vs. SHE to approximately 1200 mV vs. SHE. Again, this is consistent with the observations from the creviced samples. In earlier studies by the principal investigator, it has been found that low-level chromium contamination in ground water is usually in the hexavalent oxidation state (Farmer et al. 1996). In general, dissolved iron measured during the crevice experiments appears to be Fe(II) in acidic media and Fe(III) in near-neutral and alkaline solutions (table 3). In the case of cyclic polarization measurements, the dissolved iron measured at the end of some cyclic polarization measurements with C-22 appeared to be in the Fe(III) state. This is probably due to the high electrochemical potential at which these species were generated during the potential scan. Note that the reversal potential was approximately 1200 mV vs. Ag/AgCl during these scans. These

  10. Ion-induced surface modification of alloys

    International Nuclear Information System (INIS)

    In addition to the accumulation of the implanted species, a considerable number of processes can affect the composition of an alloy in the surface region during ion bombardment. Collisions of energetic ions with atoms of the alloy induce local rearrangement of atoms by displacements, replacement sequences and by spontaneous migration and recombination of defects within cascades. Point defects form clusters, voids, dislocation loops and networks. Preferential sputtering of elements changes the composition of the surface. At temperatures sufficient for thermal migration of point defects, radiation-enhanced diffusion promotes alloy component redistribution within and beyond the damage layer. Fluxes of interstitials and vacancies toward the surface and into the interior of the target induce fluxes of alloying elements leading to depth-dependent compositional changes. Moreover, Gibbsian surface segregation may affect the preferential loss of alloy components by sputtering when the kinetics of equilibration of the surface composition becomes competitive with the sputtering rate. Temperature, time, current density and ion energy can be used to influence the individual processes contributing to compositional changes and, thus, produce a rich variety of composition profiles near surfaces. 42 references

  11. Radiation-induced segregation in titanium alloys

    International Nuclear Information System (INIS)

    Radiation-induced segregation (RIS) of V, Mo, Nb, Ta, Zr, and Sn in binary titanium alloys was investigated to test the solute size effect correlation in hcp alloys. Undersize Mo segregates weakly toward the sinks. Nb and Ta, which are slightly oversize in Ti, undergo little or no RIS. Oversize Zr solute in Ti segregates away from the sinks, whereas undersize Ti solute in Zr is enriched at sinks. All of these results are in accord with the solute size effect correlation. Surprisingly, Sn, which is significantly oversize in Ti, appears to segregate very little. The postirradiation annealing of Ti-3V and Ti-8Al-1V-1Mo confirmed that segregation of undersize V toward sinks is radiation-induced. Measurements of temperature and dose dependence in binary and complex alloys showed that the degree of V segregation has a maximum at proportional6000C and obeys parabolic growth kinetics in its early stages but probably saturates at a rather low dose (proportional0.8 dpa). (orig.)

  12. Metal induced crystallization of silicon germanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gjukic, M.

    2007-05-15

    In the framework of this thesis the applicability of the aluminium-induced layer exchange on binary silicon germanium alloys was studied. It is here for the first time shown that polycrstalline silicon-germanium layers can be fabricated over the whole composition range by the aluminium-induced layer exchange. The experimental results prove thet the resulting material exhibits a polycrystalline character with typocal grain sizes of 10-100 {mu}m. Raman measurements confirm that the structural properties of the resulting layers are because of the large crystallites more comparable with monocrystalline than with nano- or microcrystalline silicon-germanium. The alloy ratio of the polycrystalline layer correspondes to the chemical composition of the amorphous starting layer. The polycrystalline silicon-germanium layers possess in the range of the interband transitions a reflection spectrum, as it is otherwise only known from monocrystalline reference layers. The improvement of the absorption in the photovoltaically relevant spectral range aimed by the application of silicon-germanium could be also proved by absorption measurments. Strongly correlated with the structural properties of the polycrystalline layers and the electronic band structure resulting from this are beside the optical properties also the electrical properties of the material, especially the charge-carrier mobility and the doping concentration. For binary silicon-germanium layers the hole concentration of about 2 x 10{sup 18} cm{sup -3} for pure silicon increrases to about 5 x 10{sup 20} cm{sub -3} for pure germanium. Temperature-resolved measurements were applied in order to detect doping levels respectively semiconductor-metal transitions. In the last part of the thesis the hydrogen passivation of polycrystalline thin silicon-germanium layers, which were fabricated by means of aluminium-induced layer exchange, is treated.

  13. The Susceptibility to Hydrogen Induced Stress Cracking for Alloy 718 and Alloy 725

    OpenAIRE

    Stenerud, Gaute

    2014-01-01

    The Hydrogen Induced Stress Cracking (HISC) susceptibility of Alloy 718 and Alloy 725 where examined and compared. Pre-charged samples of each alloy where stepwise loaded during polarization in Cortest Proof rings. A safe load was found from this stepwise loading. To confirm that these load levels were safe, pre-charged samples were loaded to this load for 30 days during cathodic polarization. After fracture the fracture surfaces were examined in scanning electron microscope and the hydrogen ...

  14. Irradiation induced surface segregation in concentrated alloys: a contribution

    International Nuclear Information System (INIS)

    A new computer modelization of irradiation induced surface segregation is presented together with some experimental determinations in binary and ternary alloys. The model we propose handles the alloy thermodynamics and kinetics at the same level of sophistication. Diffusion is described at the atomistic level and proceeds vis the jumps of point defects (vacancies, dumb-bell interstitials): the various jump frequencies depend on the local composition in a manner consistent with the thermodynamics of the alloy. For application to specific alloys, we have chosen the simplest statistical approximation: pair interactions in the Bragg Williams approximation. For a system which exhibits the thermodynamics and kinetics features of Ni-Cu alloys, the model generates the behaviour parameters (flux and temperature) and of alloy composition. Quantitative agreement with the published experimental results (two compositions, three temperatures) is obtained with a single set of parameters. Modelling austenitic steels used in nuclear industry requires taking into account the contribution of dumbbells to mass transport. The effects of this latter contribution are studied on a model of Ni-Fe. Interstitial trapping on dilute impurities is shown to delay or even suppress the irradiation induced segregation. Such an effect is indeed observed in the experiments we report on Fe50Ni50 and Fe49Ni50Hf1 alloys. (author)

  15. Stress Induced Phase Transition of Iron-Rhodium Alloys

    OpenAIRE

    Takahashi, M; Oshima, R.

    1995-01-01

    Stress-induced phase transitions(B2-L10, B2-fcc) on an FeRh alloy were investigated with X-ray diffraction (XRD) and transmission electron microscopy(TEM). An Fe-50.5at%Rh alloy was rolled to 80µm thickness, and annealed at 1370K for 173ks. Annealed sample sheets were cold rolled at various rolling rates, and changes of the sample alloy on the phase state were investigated with XRD. The L10 phase appeared in the early stage of cold work. With heavy work appearance of the fcc phase and consequ...

  16. Radiation induced segregation and point defects in binary copper alloys

    International Nuclear Information System (INIS)

    Considerable progress, both theoretical and experimental, has been made in establishing and understanding the influence of factors such as temperature, time, displacement rate dependence and the effect of initial solute misfit on radiation induced solute diffusion and segregation. During irradiation, the composition of the alloy changes locally, due to defect flux driven non-equilibrium segregation near sinks such as voids, external surfaces and grain boundaries. This change in composition could influence properties and phenomena such as ductility, corrosion resistance, stress corrosion cracking, sputtering and blistering of materials used in thermo-nuclear reactors. In this work, the effect of 1 MeV electron irradiation on the initiation and development of segregation and defect diffusion in binary copper alloys has been studied in situ, with the aid of a high voltage electron microscope. The binary copper alloys had Be, Pt and Sn as alloying elements which had atomic radii less than, similar and greater than that of copper, respectively. It has been observed that in a wide irradiation temperature range, stabilization and growth of dislocation loops took place in Cu-Sn and Cu-Pt alloys. Whereas in the Cu-Be alloy, radiation induced precipitates formed and transformed to the stable γ phase. (Author)

  17. STRESS INDUCED NITROGEN DIFFUSION IN NITRITED CoCr ALLOY

    Directory of Open Access Journals (Sweden)

    AKVILĖ PETRAITIENĖ

    2015-03-01

    Full Text Available In the present study the nitrogen transport mechanism in plasma nitrited CoCr alloy at moderate temperature ( 400ºC is explained by non-Fickian diffusion model. This mechanism is considered by stress induced diffusion model. The model involves diffusion of nitrogen induced by internal stresses created during nitriding process. The model considers the diffusion of nitrogen in the presence of  internal stresses gradient induced by penetrating nitrogen as the next driving force of diffusion after concentration gradient. This model is commonly used for analysis of stainless steel nitriding, however, in this work it is shown that the same nitrogen penetration mechanism takes place in CoCr alloy. For mathematical description of stress induced diffusion process the equation of baro-diffusion is used which involves concentration dependant baro-diffusion concentration. For calculation of stress gradient it is assumed that stress depth profile linearly relates with nitrogen concentration depth profile. The fitting is done using experimental curves of nitrogen depth profiles for medical grade CoCr alloy (ISO 5831-12 nitrited at 400 ºC temperature. The experimental curves are taken from literature. The nitriding duration was 2h, 6h, 20h. Calculated nitrogen depth profiles in CoCr alloy are in good agreement with experimental nitrogen depth profiles.  The diffusion coefficient D is found from fitting of experimental data.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5711

  18. Vibrational spectrum of solid picene (C_22H_14)

    OpenAIRE

    Joseph, B; Boeri, L.; Malavasi, L.; Capitani, F.; Artioli, G. A.; Protti, S.; Fagnoni, M; Albini, A; Marini, C.; Baldassarre, L.; Perucchi, A.; Lupi, S.; Postorino, P.; Dore, P.

    2012-01-01

    Recently, Mitsuhashi et al., have observed superconductivity with transition temperature up to 18 K in potassium doped picene (C22H14), a polycyclic aromatic hydrocarbon compound [Nature 464 (2010) 76]. Theoretical analysis indicate the importance of electron-phonon coupling in the superconducting mechanisms of these systems, with different emphasis on inter- and intra-molecular vibrations, depending on the approximations used. Here we present a combined experimental and ab-initio study of th...

  19. Radiation induced structural changes in alpha-copper-zinc alloys

    International Nuclear Information System (INIS)

    During irradiation of alpha-copper-zinc alloys with high energy electrons and protons a decrease of the electrical resistivity due to an increase of the degree of short range order is observed through radiation enhanced diffusion followed by an increase of the electrical resistivity through the formation of radiation induced interstitial clusters. The initial formation rate of interstitial clusters increases about linearly with the displacement rate for electron and proton irradiation. The largest initial formation rate is found between 60 and 1300C becoming negligibly small above 1580C and decreases drastically below 600C. The dynamic steady state interstitial cluster concentration increases with decreasing irradiation temperature in the investigated temperature range between 158 and 400C. Above 1580C the formation rate of interstitial clusters is negligibly small. Thus the transition temperature for radiation induced interstitial cluster formation is 1580C, depending mainly on the migration activation energy of vacancies. The radiation induced interstitial clusters are precipitates in those alloys in which the diffusion rate of the undersized component atoms via an interstitialcy diffusion mechanism is larger than that of the other atoms

  20. Current induced magnetization reversal in spin valves with Heusler alloys

    International Nuclear Information System (INIS)

    Current induced magnetization reversal using current-perpendicular-to-plane (CPP) spin valves devises with Co2MnGe, Co2FeSi, and Co75Fe25 alloys were investigated. Film stacks of Si/SiO2/Cu/IrMn/Heusler-pinned-layer/Cu/Heusler-free-layer were deposited by DC magnetron sputtering followed by post-annealing. Saturation magnetization (B s) of Co2MnGe, Co2FeSi, and Co75Fe25 are 12.7, 14.0, and 25 kg, respectively and magnetoresistance (MR) ratios of spin valves with the Co2MnGe, Co2FeSi, and Co75Fe25 are 3.6%, 3.5%, and 2.2%, respectively. The B s values and MR ratios obtained for Co2MnGe and Co2FeSi spin valves were smaller and larger, respectively, than those obtained for Co75Fe25. We speculated that the large MR ratios could be attributed to larger spin polarization of Heusler alloys. J c0 of Co2MnGe, Co2FeSi, and Co75Fe25 spin valves were 1.6x107, 2.7x107, and 5.1x107 A/cm2, respectively. The thermal factors of Co2MnGe, Co2FeSi, and Co75Fe25 were 65, 48, and 55, respectively. Using the Heusler alloys, we successfully reduced the intrinsic critical current without degrading the thermal factor

  1. The correlation between swelling and radiation-induced segregation in iron-chromium-nickel alloys

    International Nuclear Information System (INIS)

    The magnitudes of both void swelling and radiation-induced segregation (RIS) in iron-chromium-nickel alloys are dependent on bulk alloy composition. Because the diffusivity of nickel via the vacancy flux is slow relative to chromium, nickel enriches and chromium depletes at void surfaces during irradiation. This local composition change reduces the subsequent vacancy flux to the void, thereby reducing void swelling. In this work, the resistance to swelling from major element segregation is estimated using diffusivities derived from grain boundary segregation measurements in irradiated iron-chromium-nickel alloys. The resistance to void swelling in iron- and nickel-base alloys correlates with the segregation and both are functions of bulk alloy composition. Alloys that display the greatest amount of nickel enrichment and chromium depletion are found to be most resistant to void swelling, as predicted. Additionally, swelling is shown to be greater in alloys in which the RIS profiles are slow to develop

  2. Vibrational spectrum of solid picene (C22H14).

    Science.gov (United States)

    Joseph, B; Boeri, L; Malavasi, L; Capitani, F; Artioli, G A; Protti, S; Fagnoni, M; Albini, A; Marini, C; Baldassarre, L; Perucchi, A; Lupi, S; Postorino, P; Dore, P

    2012-06-27

    Recently, Mitsuhashi et al observed superconductivity with a transition temperature up to 18 K in potassium doped picene (C(22)H(14)), a polycyclic aromatic hydrocarbon compound (Mitsuhashi et al 2010 Nature 464 76). Theoretical analysis indicates the importance of electron-phonon coupling in the superconducting mechanisms of these systems, with different emphasis on inter- and intra-molecular vibrations, depending on the approximations used. Here we present a combined experimental and ab initio study of the Raman and infrared spectrum of undoped solid picene, which allows us to unambiguously assign the vibrational modes. This combined study enables the identification of the modes which couple strongly to electrons and hence can play an important role in the superconducting properties of the doped samples. PMID:22635521

  3. Vibrational spectrum of solid picene (C22H14)

    International Nuclear Information System (INIS)

    Recently, Mitsuhashi et al observed superconductivity with a transition temperature up to 18 K in potassium doped picene (C22H14), a polycyclic aromatic hydrocarbon compound (Mitsuhashi et al 2010 Nature 464 76). Theoretical analysis indicates the importance of electron-phonon coupling in the superconducting mechanisms of these systems, with different emphasis on inter- and intra-molecular vibrations, depending on the approximations used. Here we present a combined experimental and ab initio study of the Raman and infrared spectrum of undoped solid picene, which allows us to unambiguously assign the vibrational modes. This combined study enables the identification of the modes which couple strongly to electrons and hence can play an important role in the superconducting properties of the doped samples. (fast track communication)

  4. Radiation-induced segregation in Cu-Au alloys

    International Nuclear Information System (INIS)

    Radiation-induced segregation in a Cu-1 at. % Au alloy was investigated using in situ Rutherford Backscattering Spectrometry. Irradiation with 1.8-MeV He produced nonequilibrium Au atom depletion in the near surface region. The amount of segregation was measured as a function of dose, dose rate and temperature. Segregation was observed between 300 and 5000C. For a calculated dose rate of 3.9 x 10-5 dpa/s, the radiation-induced segregation rate peaked near 4000C. Theoretical analysis based on the Johnson-Lam model predicted that the amount of segregation would be directly proportional to dose at the early stage of irradiation, would deviate from linearity with a continuously decreasing slope at intermediate doses, and finally approach a constant value after high doses. The analysis also predicted that the segregation rate would vary as the -1/4th power of the dose rate at constant dose in the low temperature region. These predictions were all verified experimentally. A procedure for extracting relative defect production efficiencies from similar measurements is discussed

  5. Application of laser-induced breakdown spectroscopy (LIBS) analysis to molten alloy production process

    International Nuclear Information System (INIS)

    We applied laser-induced breakdown spectroscopy (LIBS) analysis to the molten alloy production process, in which simulated metals (Zr, Cu, Sm, Ce) are used instead of nuclear metallic fuels containing minor actinide (MA). Our aim is in-situ monitoring of the elementary composition of a molten alloy's surface in a chamber and the vapor particles generated from that surface. We successfully observed the variation in the ratio of the elementary composition of the molten alloy's surface in the crucible by depending on the crucible's temperature. The elementary composition of the vapor particles in the molten alloy chamber was also measured. Practical experimental results show that the LIBS technique is very useful for investigating elementary composition in the molten alloy production process and understanding molten alloy behavior in crucibles. (author)

  6. Ion bombardment-induced changes in the surface composition of binary alloys

    International Nuclear Information System (INIS)

    Redistribution of alloy components during heavy-ion bombardment was investigated using a kinetic model that includes the effects of radiation-induced segregation and preferential sputtering. Theoretical predictions are qualitatively compared with recent experimental measurements

  7. Effect of temperature on the crevice corrosion resistance of Ni-Cr-Mo alloys as engineered barriers in nuclear waste repositories

    International Nuclear Information System (INIS)

    Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly corrosive environments. Alloys 625, C-22, C-22HS and Hybrid-BC1 are considered among candidates as engineered barriers of nuclear repositories. The objective of the present work was to assess the effect of temperature on the crevice corrosion resistance of these alloys. The crevice corrosion re-passivation potential (ECO) of the tested alloys was determined by the Potentiodynamic-Galvanostatic-Potentiodynamic (PD-GS-PD) method. Alloy Hybrid-BC1 was the most resistant to chloride-induced crevice corrosion, followed by alloys C-22HS, C-22 and 625. ECO showed a linear decrease with temperature. There is a temperature above which ECO does not decrease anymore, reaching a minimum value. This ECO value is a strong parameter for assessing the localized corrosion susceptibility of a material in a long term timescale, since it is independent of temperature, chloride concentration and geometrical variables such as crevicing mechanism, crevice gap and type of crevice formers. (author)

  8. Irradiation-induced patterning in dilute Cu–Fe alloys

    International Nuclear Information System (INIS)

    Compositional patterning in dilute Cu1−xFex (x ≈ 12%) induced by 1.8 MeV Kr+ irradiation was studied as a function of temperature using atom probe tomography. Irradiation near room temperature led to homogenization of the sample, whereas irradiation at 300 °C and above led to precipitation and macroscopic coarsening. Between these two temperatures the irradiated alloys formed steady state patterns of composition where precipitates grew to a fixed size. The size in this regime increased somewhat with temperature. It was also observed that the steady state concentrations of Fe in Cu matrix and Cu in the Fe precipitates both greatly exceeded their equilibrium solubilities, with the degree of supersaturation in each phase decreasing with increasing temperature. In the macroscopic coarsening regime, the Fe-rich precipitates showed indications of a “cherry-pit” structure, with Cu precipitates forming within the Fe precipitates. In the patterning regime, interfaces between Fe-rich precipitates and the Cu-rich matrix were irregular and diffuse

  9. Influence of solutes on heavy ion induced void-swelling in binary copper alloys

    International Nuclear Information System (INIS)

    As radiation induced swelling of metals depends on their constitution, swelling of copper and copper alloys with low solute concentration is studied. Diffusion coefficients and solubility of solute in copper were used as criteria of selection of the alloys. The samples were irradiated by 200keV copper ions. Swelling and void densities were measured by transmission electron microscopy. The measurements show low dependence of swelling upon the diffusibility of the solute in the solvent and a strong dependence on their concentration. Alloys of 0.1at% solute show more swelling than pure copper, and alloys of 1at% show less swelling under the irradiation conditions. The different swelling behavior in Cu-Ni alloys is due to the different void densities. (orig.)

  10. Hydrogen-induced hardening of Ti–6Al–4V alloy in β phase field

    International Nuclear Information System (INIS)

    Highlights: • Hydrogen can be retained in Ti–6Al–4V alloy at temperatures up to 1100 °C. • Hydrogen induces increased flow stress and work hardening rate of Ti–6Al–4V alloy. • Hydrogen has a positive effect on the development of twining in Ti–6Al–4V alloy. • Hydrogen-induced twinning plays a key role in the enhancement of work hardening. - Abstract: Isothermal compression tests were conducted to investigate the hot deformation behaviour of a Ti–6Al–4V alloy with different hydrogen contents (0, 0.35 and 0.6 wt.%) at temperatures of 1050–1100 °C, and strain rates of 0.005, 0.01, 0.1 and 1 s−1 respectively. The microstructural evolution was investigated via optical microscope (OM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The mechanism of hydrogen-induced hardening was discussed. The experimental results showed that hydrogen could be retained in Ti–6Al–4V alloy even though the temperature was increased to 1100 °C in air. δ hydride with an face-centred cubic (FCC) crystal structure existed in the deformed matrix, and the size of δ hydride reduced when the deformation temperature was increased from 1050 to 1100 °C. Hydrogen induced the increased flow stress and work hardening rate of Ti–6Al–4V alloy when deformed in β phase field. Hydrogen had a positive effect on the development of twinning in Ti–6Al–4V alloy. Based on the analysis of both hot deformation behaviour and microstructural evolution, it is indicated that the hydrogen-induced twinning plays a key role in the enhancement of work hardening of Ti–6Al–4V alloy in β phase field

  11. Radiation-Induced Dislocation and Growth Behavior of Zirconium and Zirconium Alloys - A Review

    International Nuclear Information System (INIS)

    Zirconium and zirconium alloys are widely used as nuclear reactor core materials such as fuel cladding and guide tubes because they have excellent corrosion- and radiation-resistant properties. In the reactor core, zirconium alloys are subjected to high-energy neutron fluence, causing radiation-induced dislocation and growth. To discern a possible correlation between radiation-induced dislocation and growth, characteristics of dislocation and growth in zirconium and its alloys are examined. The radiation-induced dislocation including and dislocation loops is reviewed in various temperature and fluence ranges, and their growth behavior is examined in the same way. To further a fundamental understanding, radiation-induced growth prediction models are briefly reviewed. This research will assist in the design of zirconium based components as well as the safety analysis of various reactor conditions, in both research and commercial reactors

  12. Nanocrystallization of Coarse Primary Phases in Al- and Mg-Based Alloys Induced by HCPEB Treatment

    OpenAIRE

    Gao Bo; He Jidong; Tu Ganfeng; Hu Liang

    2013-01-01

    This paper reports on a phenomenon associated with high-current pulsed electron beam (HCPEB) treatment: surface nanocrystallization of coarse primary phase in hypereutectic Al17.5Si and quasicrystal alloys after multiple pulses of HCPEB irradiation. The HCPEB treatment induces superfast heating and diffusion of alloying elements and heterogeneous nucleation in a melting solution, followed by rapid solidification and cooling of the material surfaces. Consequently, nanostructured surface layers...

  13. Radiation-induced creep of copper, aluminium and their alloys

    International Nuclear Information System (INIS)

    The results of creep studies on copper, aluminium and their alloys with and without neutron irradiation are presented. The experiments are carried out at the WWR-K reactor at the neutron fluence of 1.4.1016 n/m2.s (2.5.1016 n/m2.s, E>0.1 MeV). Polycrystalline copper (99.99 and 99.95%), aluminium (99.99%) and the alloys of copper with 4 at% of titanium, of aluminium with 4.2% of copper are studied within the temperature interval 0.31-0.51 Tm. (orig.)

  14. Effects of strain and trapping on hydrogen-induced cracking in high strength low alloy steels

    OpenAIRE

    Bosch, Cédric; Delafosse, David; Longaygue, Xavier

    2010-01-01

    International audience In pearlitic steels, hydrogen trapping at interphase boundaries may induce hydrogen- cracking in the absence of external applied stress such as in blistering and Hydrogen Induced Cracking. However, in low alloy steels containing a much lower density of such trapping sites and/or when hydrogen activity is reduced, most instances of hydrogen-induced cracking involve strong interactions between local plasticity and hydrogen effects. We investigated the effects of these ...

  15. Lead induced intergranular fracture in aluminum alloy AA6262

    NARCIS (Netherlands)

    De Hosson, JTM

    2003-01-01

    The influence of lead on the fracture behavior of aluminum alloy AA6262 is investigated. Under certain conditions, the mode of fracture changes from transgranular microvoid coalescence to an intergranular mechanism. Three different intergranular fracture mechanisms are observed: liquid metal embritt

  16. Quantitative analysis of impurities in aluminum alloys by laser-induced breakdown spectroscopy without internal calibration

    Institute of Scientific and Technical Information of China (English)

    LI Hong-kun; LIU Ming; CHEN Zhi-jiang; LI Run-hua

    2008-01-01

    To develop a fast and sensitive alloy elemental analysis method, a laser-induced breakdown spectroscopy(LIBS) system was established and used to carry out quantitative analysis of impurities in aluminum alloys in air at atmospheric pressure. A digital storage oscilloscope was used as signal recording instrument, instead of traditional gate integrator or Boxcar averager, to reduce the cost of the whole system. Linear calibration curves in the concentration range of 4×10-5-10-2 are built for Mg, Cr, Mn, Cu and Zn using absolute line intensity without internal calibrations. Limits of detection for these five elements in aluminum alloy are determined to be (2-90)×10-6. It is demonstrated that LIBS can provide quantitative trace elemental analysis in alloys even without internal calibration. This approach is easy to use in metallurgy industries and relative research fields.

  17. Nanocrystallization of Coarse Primary Phases in Al- and Mg-Based Alloys Induced by HCPEB Treatment

    Directory of Open Access Journals (Sweden)

    Gao Bo

    2013-01-01

    Full Text Available This paper reports on a phenomenon associated with high-current pulsed electron beam (HCPEB treatment: surface nanocrystallization of coarse primary phase in hypereutectic Al17.5Si and quasicrystal alloys after multiple pulses of HCPEB irradiation. The HCPEB treatment induces superfast heating and diffusion of alloying elements and heterogeneous nucleation in a melting solution, followed by rapid solidification and cooling of the material surfaces. Consequently, nanostructured surface layers can be achieved easily. Nano-Si phase and nano-quasicrystal phase formation on the modified surface layer of hypereutectic Al17.5Si alloy and quasicrystal alloy (Mg37Zn60Y3 show a potential for surface nanocrystallization of materials with enhanced properties by HCPEB treatment.

  18. Irradiation-induced creep and microstructural development in precipitation-hardened nickel-aluminium alloys

    International Nuclear Information System (INIS)

    Irradiation-induced creep in solid-solution Ni-8.5 at% AL and precipitation-hardened Ni-13.1 at% Al alloys was studied by bombarding miniaturized specimens with 6.2 MeV protons at 3000C under different tensile stresses. After irradiation transmission electron microscopic (TEM) investigations were made to observe the precipitate structure under irradiation for different experimental parameters. Moreover, the irradiation-induced changes in precipitate structure and changes of Al-concentrations in the matrix in Ni-13.1 at% Al alloys were studied by electrical resistivity measurements during irradiation. For comparison, the electrical resistivity of unirradiated specimens was also measured after thermal aging for different times. For correlation, TEM analysis was performed on irradiated and unirradiated aged specimens. Tensile tests on annealed and aged Ni-Al alloys were also done at various temperatures. (orig./RK)

  19. Segregation and diffusion of deffects induced by radiation in binary copper alloys

    International Nuclear Information System (INIS)

    Actually considerable theoretical and experimental progress has been made in establishing and in understanding the general feactures of the Radiation Induced Solute Difusion or Segregation such as its temperature, time and displacement rate dependence and the effects of some important materials factors such as the initial solute misfit. During irradiation, the local alloy compositions will change by defect flux driven, non-equilibrium segregation near sinks such as voids, external surfaces and grain boundaries and the compositional change are likely to influence a number of properties and phenomena important to Thermonuclear Reactors, as for example, Ductility, Corrosion, Stress, Corrosion Craking, Sputtering and Blistering. Our work is correlated with the 1 MeV electrons irradiations effects in Copper alloys where the alloying elements are Be, Pt, Sn. These three elements are undersized, similar and oversized relating the Copper atom radius, respectively. How starts and develops the Segregation Induced by Irradiation 'In Situ' with help of the High Voltage Electron Microscopy as technique. (Author)

  20. Irradiation-induced precipitation in Ni--Si alloys

    International Nuclear Information System (INIS)

    The microstructures of Ni+ ion-irradiated Ni--Si solid-solution alloys, containing 2, 4, 6 and 8 at. percent Si were investigated as a function of dose, dose-rate, and temperature. Results of transmission electron microscopy and other data show the precipitation of γ' (Ni3Si) in all samples irradiated at 5000C. Characteristics of the precipitates are described and a mechanism for their formation is suggested. (U.S.)

  1. Orbital-frustration-induced ordering in semiconductor alloys

    Science.gov (United States)

    Liu, Kai; Yin, Wanjian; Chen, Shiyou; Gong, X. G.; Wei, S.-H.; Xiang, H. J.

    2016-05-01

    It is well known that ternary zinc-blende semiconductors are always more stable in the chalcopyrite (CH) structure than the Cu-Au (CA) structure because the CH structure has a large Coulomb interaction and a reduced strain energy. Surprisingly, an experimental study showed that the ZnFeS e2 alloy takes the CA order as the ground-state structure, which is consistent with our density functional theory calculations showing that the CA order has lower energy than the CH order for ZnFeS e2 . We reveal that the orbital degree of freedom of a high-spin F e2 + ion (d6) in the tetrahedral crystal field plays a key role in stabilizing the CA order. First, the spin-minority d electron of the F e2 + ion tends to occupy the dx2-y2-like orbital instead of the d3 z2-r2-like orbital because of its large negative Coulomb energy. Second, for a nearest-neighboring F e2 + pair, two spin-minority d electrons with occupied dx2-y2-like orbitals on the plane containing the Fe-Fe bond have lower electronic kinetic energies. Both conditions can be satisfied in the CA ordered ZnFeS e2 alloy, whereas there is an orbital frustration in the CH structure. Our results suggest that the orbital degree of freedom provides a new way to manipulate the structure and properties of alloys.

  2. Irradiation-induced precipitation and solute segregation in alloys. Fourth annual progress report, February 1, 1981-March 31, 1982

    International Nuclear Information System (INIS)

    The studies of irradiation-induced solute segregation (IISS) and irradiation-induced precipitation (IIP) in Ni-Si and Pd-Fe alloys have been completed. Progress is reported for several other projects: irradiation damage in binary Pd-Cr, -Mn and -V alloys (15 at. %); IIP in Pd-Mo and Pd-W alloys; IIP in Pd-25 at. % Cr alloy; and irradiation damage effects in proton-bombarded metallic glasses (Ni-65 Zr, 40 Fe 40 Ni 14 P6B). 27 figures

  3. Phase Stability and Stress-Induced Transformations in Beta Titanium Alloys

    Science.gov (United States)

    Kolli, R. Prakash; Joost, William J.; Ankem, Sreeramamurthy

    2015-06-01

    In this article, we provide a brief review of the recent developments related to the relationship between phase stability and stress-induced transformations in metastable body-centered-cubic β-phase titanium alloys. Stress-induced transformations occur during tensile, compressive, and creep loading and influence the mechanical response. These transformations are not fully understood and increased understanding of these mechanisms will permit future development of improved alloys for aerospace, biomedical, and energy applications. In the first part of this article, we review phase stability and discuss a few recent developments. In the second section, we discuss the current status of understanding stress-induced transformations and several areas that require further study. We also provide our perspective on the direction of future research efforts. Additionally, we address the occurrence of the hcp ω-phase and the orthorhombic α″-martensite phase stress-induced transformations.

  4. Transformation-Induced Creep and Creep Recovery of Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    Elzbieta A. Pieczyska

    2012-05-01

    Full Text Available If the shape memory alloy is subjected to the subloop loading under the stress-controlled condition, creep and creep recovery can appear based on the martensitic transformation. In the design of shape memory alloy elements, these deformation properties are important since the deflection of shape memory alloy elements can change under constant stress. The conditions for the progress of the martensitic transformation are discussed based on the kinetics of the martensitic transformation for the shape memory alloy. During loading under constant stress rate, temperature increases due to the stress-induced martensitic transformation. If stress is held constant during the martensitic transformation stage in the loading process, temperature decreases and the condition for the progress of the martensitic transformation is satisfied, resulting in the transformation-induced creep deformation. If stress is held constant during the reverse transformation stage in the unloading process, creep recovery appears due to the reverse transformation. The details for these thermomechanical properties are investigated experimentally for TiNi shape memory alloy, which is most widely used in practical applications. The volume fraction of the martensitic phase increases in proportion to an increase in creep strain.

  5. The role of interstitial binding in radiation induced segregation in W-Re alloys

    Science.gov (United States)

    Gharaee, Leili; Marian, Jaime; Erhart, Paul

    2016-07-01

    Due to their high strength and advantageous high-temperature properties, tungsten-based alloys are being considered as plasma-facing candidate materials in fusion devices. Under neutron irradiation, rhenium, which is produced by nuclear transmutation, has been found to precipitate in elongated precipitates forming thermodynamic intermetallic phases at concentrations well below the solubility limit. Recent measurements have shown that Re precipitation can lead to substantial hardening, which may have a detrimental effect on the fracture toughness of W alloys. This puzzle of sub-solubility precipitation points to the role played by irradiation induced defects, specifically mixed solute-W interstitials. Here, using first-principles calculations based on density functional theory, we study the energetics of mixed interstitial defects in W-Re, W-V, and W-Ti alloys, as well as the heat of mixing for each substitutional solute. We find that mixed interstitials in all systems are strongly attracted to each other with binding energies of -2.4 to -3.2 eV and form interstitial pairs that are aligned along parallel first-neighbor strings. Low barriers for defect translation and rotation enable defect agglomeration and alignment even at moderate temperatures. We propose that these elongated agglomerates of mixed-interstitials may act as precursors for the formation of needle-shaped intermetallic precipitates. This interstitial-based mechanism is not limited to radiation induced segregation and precipitation in W-Re alloys but is also applicable to other body-centered cubic alloys.

  6. Bulk and surface contributions to enhanced solar-cell performance induced by aluminium alloying

    Energy Technology Data Exchange (ETDEWEB)

    Loelgen, P.; Bisschop, F.J. (FOM-Instituut voor Atoom- en Molecuulfysica, Amsterdam (Netherlands)); Sinke, W.C.; Steeman, R.A. (Netherlands Energy Research Foundation (ECN), Petten (Netherlands)); Verhoef, L.A.; Michiels, P.P.; Van Zolingen, R.J.C. (R S Renewable Energy Systems, Amsterdam (Netherlands))

    1991-11-01

    Use was made of the Light Beam Induced Current Decay technique to study Al-alloying effects in semi-crystalline Si solar cells. With this technique one is able to separate the minority-carrier diffusion length in the Si bulk and the effective back-surface recombination velocity. An increase in diffusion length of about 30% was measured, as well as a reduction of the effective back-surface recombination velocity to {<=} 10{sup 3} cm/s after Al-alloying. We investigated the effects of various processing conditions on both recombination mechanisms. Consequences for low-cost Si solar cell design are discussed. 8 figs., 1 tab., 9 refs.

  7. New observations on formation of thermally induced martensite in Fe–30%Ni–1%Pd alloy

    Indian Academy of Sciences (India)

    Gokcen Yildiz; Yasin Gokturk Yildiz; Saffet Nezir

    2013-02-01

    Kinetical, morphological, crystallographical and thermal characteristics of thermally induced martensite in an Fe–30%Ni–1%Pd alloy has been studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction method. Kinetics of transformation was found to be as athermal. SEM and TEM observations and X-ray method revealed ' () martensite formation in the austenite phase of alloy by thermal effect. The crystallographic orientation relationship between austenite and ' () martensite was found to be having Kurdjumov–Sachs (K–S) type relationship. In addition, the lattice parameters of austenite and martensite phases were calculated from X-ray diffraction patterns.

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

  9. Corrosion resistance of Ni-Cr-Mo alloys. Chemical composition and metallurgical condition's effects

    International Nuclear Information System (INIS)

    Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly-corrosive environments. This versatility is due to the excellent performance of nickel in hot alkaline solutions and the beneficial effect of chromium and molybdenum in oxidizing and reducing conditions, respectively. Alloy C-22 (22 % Cr-13 % Mo-3% W) is a well known versatile member of this family. Due to its excellent corrosion resistance in a wide variety of environments, Alloy C-22 has been selected for the fabrication of the corrosion-resistant outer shell of the high-level nuclear waste container. The increasing demand of the industry for corrosion resistant alloys with particular properties of corrosion and mechanical resistance has led to the development of new alloys. Alloy C-22HS (Ni-21 % Cr-17 % Mo) is a new high-strength corrosion resistant material recently developed and introduced into the market. This alloy provides a corrosion resistance comparable with that of other C-type alloys, and it can also be age hardened to effectively double its yield strength. HASTELLOY HYBRID-BC1 (Ni-22 % Mo-15 % Cr) is a new development intended for filling the gap between Ni-Mo and Ni-Cr-Mo alloys. This novel alloy is able to withstand HCl and H2SO4, even in the presence of dissolved oxygen and other oxidizing species. Its resistance to chloride-induced pitting corrosion, crevice corrosion and stress corrosion cracking is also remarkable. Thermal aging of Ni-Cr-Mo alloys leads to microstructure changes depending on the temperature range and exposure time at temperature. A Long Range Ordering (LRO) reaction can occur in the range of 350 C degrees to 600 C degrees, producing an ordered Ni2(Cr,Mo) phase. This ordering reaction does not seem to affect the corrosion resistance and produces only a slight loss in ductility. LRO transformation is homogeneous and has proven to be useful to fabricate the age-hard enable Alloy C22-HS. Tetrahedral Close Packed (TCP) phases, like μ, σ and P, may

  10. Field Induced Magnetic Moments in a Metastable Iron-Mercury Alloy

    DEFF Research Database (Denmark)

    Pedersen, M.S.; Mørup, Steen; Linderoth, Søren; Johansson, C.; Hanson, M.

    1996-01-01

    The magnetic properties of a metastable iron-mercury alloy have been investigated in the temperature range from 5 to 200 K by Mossbauer spectroscopy and magnetization measurements. At low temperature the magnetic moment per iron atom is larger than af alpha-Fe. The effective spontaneous magnetic...... moment for the iron-mercury alloy extrapolated to 0 K was found to be 2.40 Bohr magnetons per iron atom. By applying magnetic fields up to 12 T it was possible to further increase the magnetization. Mossbauer results showed that the high field susceptibility could not be explained by spin canting effects....... It was found that the field-induced increase of the magnetic moment in the metastable iron-mecury alloy was about 0.06 Bohr magnetons per iron atom in the temperature range from 5 to 200 K for a field change from 6 to 12 T....

  11. Low-Temperature Annealing Induced Amorphization in Nanocrystalline NiW Alloy Films

    Directory of Open Access Journals (Sweden)

    Z. Q. Chen

    2013-01-01

    Full Text Available Annealing induced amorphization in sputtered glass-forming thin films was generally observed in the supercooled liquid region. Based on X-ray diffraction and transmission electron microscope (TEM analysis, however, here, we demonstrate that nearly full amorphization could occur in nanocrystalline (NC sputtered NiW alloy films annealed at relatively low temperature. Whilst the supersaturation of W content caused by the formation of Ni4W phase played a crucial role in the amorphization process of NiW alloy films annealed at 473 K for 30 min, nearly full amorphization occurred upon further annealing of the film for 60 min. The redistribution of free volume from amorphous regions into crystalline regions was proposed as the possible mechanism underlying the nearly full amorphization observed in NiW alloys.

  12. Radiation-induced segregation of impurities and effects on the electrochemistry of nickel and stainless alloys

    International Nuclear Information System (INIS)

    Radiation-induced grain boundary segregation (RIS) of silicon and phosphorus in austenitic stainless steels is established and its influence on. electrochemical behavior investigated. Silicon enrichment increases with irradiation dose for both neutrons and heavy ions. Interfacial concentrations reach about 8 at% after irradiation exposures to 10 dpa. Phosphorus segregates strongly during initial thermal treatment, but no conclusive evidence of further boundary enrichment could be determined after irradiation. These impurities have different effects on the electrochemical behavior of Ni and Fe-Ni-Cr alloys. Silicon additions from 2 to 23 at% improves passivation behavior in the stainless alloys, but as little as 5 at% impairs passivity in nickel where the breakdown potential increased with Si content. Low levels of phosphorus increase passive currents in the stainless alloy, while completely eliminating passivity in nickel. This information is important for LWR core components

  13. On the stability of the CO adsorption-induced and self-organized CuPt surface alloy

    DEFF Research Database (Denmark)

    Andersson, Klas Jerker; Chorkendorff, Ib

    2010-01-01

    regenerated by reducing the CuOx in 100 mbar CO for 10 min at room temperature. The results show, amongst others, the stability of the CuPt surface alloy in various environments containing CO and how a novel coinage/Pt-group bimetallic surface alloy catalyst induced by CO adsorption can be reactivated before...

  14. Microbiologically induced corrosion of aluminum alloys in fuel-oil/aqueous system.

    Science.gov (United States)

    Yang, S S; Lin, J Y; Lin, Y T

    1998-09-01

    To investigate the microbiologically induced corrosion of aluminum alloys in fuel-oil/aqueous system, aluminum alloys A356, AA 5052, AA 5083 and AA 6061 were chosen as the test alloys and Cladosporium and several fuel-oil contaminated microbes isolated in Taiwan were used as test organisms. Aluminum alloy AA 5083 in fuel-oil/aqueous system was the most susceptible material for microbial corrosion, then followed by aluminum alloys AA 5052 and A356, and AA 6061 was more resistant to microbial aggression. Mixed culture had high capability of corrosion, then followed by Penicillium sp. AM-F5, Fusarium sp. AM-F1, Pseudomonas aeruginosa AM-B5, Ps. fluorescens AM-B9, C. resinae ATCC 22712, Penicillium sp. AM-F2, Candida sp. AM-Y1 and Ps. aeruginosa AM-B11. From energy dispersive spectrometer analysis, aluminum and magnesium contents decreased in the corrosion area, while chlorine and sulfur contents increased. The major organic acid produced in fuel-oil/aqueous system was acetic acid, and the total organic acids content had a positive correlation with the degree of microbial corrosion. PMID:10496152

  15. Metastable phases in the aluminum-germanium alloy system: Synthesis by mechanical alloying and pressure induced transformations

    Energy Technology Data Exchange (ETDEWEB)

    Yvon, P.

    1994-01-01

    Al and Ge form a simple equilibrium eutectic with limited mutual solubility and no intermetallic intermediate phases. We used a regular solution approach to model effects of pressure on Al-Ge. Effects of pressure are to extend solubility of Ge in Al, to displace the eutectic composition towards the Ge rich side, and to slightly decrease the eutectic temperature. We designed thermobaric treatments to induce crystal-to-glass transformations in fine grain mixtures of Al and Ge. We used Merrill-Bassett diamond anvil cells to perform experiments at high pressures. We built an x-ray apparatus to determine the structure of alloys at pressure and from cryogenic temperatures to 400C. Two-phase Al-Ge samples with fine microstructures were prepared by splat-quenching and mechanical alloying. We observed a crystal-to-glass transformation at about 80 kbar. The amorphous phase formed was metastable at ambient temperature after pressure release. This was confirmed by TEM. The amorphous phase obtained by pressurization was found to have a liquid-like structure and was metallic. In the TEM samples we also observed the presence of a second amorphous phase formed upon release of the pressure. This second phase had a tetrahedrally-bonded continuous random network structure, similar to that of semi-conducting amorphous germanium.

  16. Inducing anisotropy in bulk Nd–Fe–Co–Al–B nanocrystalline alloys by quenching in magnetic field

    International Nuclear Information System (INIS)

    We have observed magnetic anisotropy in bulk Nd55−xCoxFe30Al10B5 (x=10, 15 and 20) alloys prepared by copper mold suction casting method with a presence of external magnetic field (quenching field) μ0H=0.25 T. By changing direction of the measuring field from perpendicular to parallel one in comparison with that of the quenching field, coercive force of the alloys slightly decreases while remanent magnetization and squareness of hysteresis loop increase more clearly. It is also found that the higher Co-concentration in the alloys the larger magnetic anisotropy is induced. The structure analyses manifest nanocrystalline particles embedded in residual amorphous matrix of the alloys. The size of the particles is in range of 10–30 nm and their crystalline phases consist of Nd2(Fe,Co)14B, Nd3Co, Nd3Al, NdAl2 and Nd. - Highlights: ► Inducing anisotropy in bulk nanocrystalline alloys by quenching in magnetic field. ► Magnitude of the induced anisotropy is enhanced by Co-concentration. ► Nd2(Fe,Co)14B stick-like nanograins is main factor for anisotropy of the alloys. ► Bulk Nd–Co–Fe–Al–B nanocrystalline alloys fabricated by rapid solidification. ► High coercivities up to 1.6 T achieved in bulk Nd–Co–Fe–Al–B nanocrystalline alloys.

  17. Grain boundary chemistry effects on environment-induced crack growth of iron-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R.H.

    1992-11-01

    Relation between grain boundary chemistry and environment-induced crack growth of Fe-based alloys is reviewed. The importance of the cleanliness of steels is clearly demonstrated by direct relations between grain boundary chemistry and crack growth behavior for both H and anodic dissolution-induced crack growth. Relationships between strain to failure, work of fracture, K[sub ISCC], crack velocity and fracture mode and grain boundary chemistry are presented. Only results in which the grain boundary chemistry has been measured directly by Auger electron spectroscopy (AES) on intergranular surfaces exposed by in situ fracture have been considered in this review.

  18. Grain boundary chemistry effects on environment-induced crack growth of iron-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R.H.

    1992-11-01

    Relation between grain boundary chemistry and environment-induced crack growth of Fe-based alloys is reviewed. The importance of the cleanliness of steels is clearly demonstrated by direct relations between grain boundary chemistry and crack growth behavior for both H and anodic dissolution-induced crack growth. Relationships between strain to failure, work of fracture, K{sub ISCC}, crack velocity and fracture mode and grain boundary chemistry are presented. Only results in which the grain boundary chemistry has been measured directly by Auger electron spectroscopy (AES) on intergranular surfaces exposed by in situ fracture have been considered in this review.

  19. Ion irradiation induced disappearance of dislocations in a nickel-based alloy

    Science.gov (United States)

    Chen, H. C.; Li, D. H.; Lui, R. D.; Huang, H. F.; Li, J. J.; Lei, G. H.; Huang, Q.; Bao, L. M.; Yan, L.; Zhou, X. T.; Zhu, Z. Y.

    2016-06-01

    Under Xe ion irradiation, the microstructural evolution of a nickel based alloy, Hastelloy N (US N10003), was studied. The intrinsic dislocations are decorated with irradiation induced interstitial loops and/or clusters. Moreover, the intrinsic dislocations density reduces as the irradiation damage increases. The disappearance of the intrinsic dislocations is ascribed to the dislocations climb to the free surface by the absorption of interstitials under the ion irradiation. Moreover, the in situ annealing experiment reveals that the small interstitial loops and/or clusters induced by the ion irradiation are stable below 600 °C.

  20. Comparison of brass alloys composition by laser-induced breakdown spectroscopy and self-organizing maps

    International Nuclear Information System (INIS)

    In this paper we face the problem of assessing similarities in the composition of different metallic alloys, using the laser-induced breakdown spectroscopy technique. The possibility of determining the degree of similarity through the use of artificial neural networks and self-organizing maps is discussed. As an example, we present a case study involving the comparison of two historical brass samples, very similar in their composition. The results of the paper can be extended to many other situations, not necessarily associated with cultural heritage and archeological studies, where objects with similar composition have to be compared. - Highlights: • A method for assessing the similarity of materials analyzed by LIBS is proposed. • Two very similar fragments of historical brass were analyzed. • Using a simple artificial neural network the composition of the two alloys was determined. • The composition of the two brass alloys was the same within the experimental error. • Using self-organizing maps, the probability of the alloys to have the same composition was assessed

  1. Inhibition of Chloride Induced Crevice Corrosion in Alloy 22 by Fluoride Ions

    Energy Technology Data Exchange (ETDEWEB)

    Carranza, R M; Rodr?guez, M A; Rebak, R B

    2005-10-09

    Alloy 22 (N06022) is highly resistant to localized corrosion. Alloy 22 may be susceptible to crevice corrosion in pure chloride (Cl{sup -}) solutions under aggressive environmental conditions. The effect of the fluoride (F{sup -}) over the crevice corrosion induced by chloride ions is still not well established. The objective of the present work was to explore the crevice corrosion resistance of this alloy to different mixtures of fluorides and chlorides. Cyclic potentiodynamic polarization (CPP) tests were conducted in deaerated aqueous solutions of pure halide ions and also in different mixtures of chloride and fluoride at 90 C and pH 6. The range of chloride concentration [Cl{sup -}] was 0.001 M {le} [Cl{sup -}] {le} 1 M and the range of molar fluoride to chloride ratio [F{sup -}]/[Cl{sup -}] was 0.1 {le} [F{sup -}]/[Cl{sup -}] {le} 10. Results showed that Alloy 22 was susceptible to crevice corrosion in all the pure chloride solutions but not in the pure fluoride solutions. Fluoride ions showed an inhibitor behavior only in mixtures with a molar ratio [F{sup -}]/[Cl{sup -}] > 2. For mixtures with a molar ratio [F{sup -}]/[Cl{sup -}] of 7 and 10 the inhibition of crevice corrosion was complete.

  2. Irradiation-induced softening of Ni3P and (Ni, Fe, Cr)3P alloys

    International Nuclear Information System (INIS)

    Production of amorphous alloys by solid state reactions (SSR) has attracted much interest during the last few years. One of the methods to induce such a reaction is the irradiation of suitable crystalline alloys by fast particles. Examination of this kind of SSR in M3P type of brazing alloys (M: Metal) is attractive because of the following reason: In brazed joints of candidate structural materials like 316L stainless steel for applications in fusion reactors, crystalline intermetallic phases have been detected which are unstable relative to the amorphous state when irradiated at moderate temperatures with fast particles. It is expected that the transition to the amorphous state is accompanied by changes of the mechanical properties, which are of fundamental interest in this context. Until now, only a few studies on the evolution of mechanical properties during amorphization have been performed. Measurements of microhardness of the crystalline and the corresponding amorphous phase do not exist to the authors knowledge. In this communication, the authors present results on changes of microhardness, due to amorphization by fast ions. The measurements have been performed on a model alloy Ni3P and on the brazed joint of stainless steel 316L, containing M3P (M: Ni, Fe, Cr) as one of the phases. Though microhardness is not a fundamental property of materials, it is a manifestation of several related properties, such as yield stress, ductility, work-hardening, elastic modulus and residual stress states. It represents a resistance for indentation and is, therefore, appropriate for comparative purposes

  3. Comparison of brass alloys composition by laser-induced breakdown spectroscopy and self-organizing maps

    Energy Technology Data Exchange (ETDEWEB)

    Pagnotta, Stefano; Grifoni, Emanuela; Legnaioli, Stefano [Applied and Laser Spectroscopy Laboratory, ICCOM-CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Lezzerini, Marco [Department of Earth Sciences, University of Pisa, Via S. Maria 53, 56126 Pisa (Italy); Lorenzetti, Giulia [Applied and Laser Spectroscopy Laboratory, ICCOM-CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Palleschi, Vincenzo, E-mail: vincenzo.palleschi@cnr.it [Applied and Laser Spectroscopy Laboratory, ICCOM-CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Department of Civilizations and Forms of Knowledge, University of Pisa, Via L. Galvani 1, 56126 Pisa (Italy)

    2015-01-01

    In this paper we face the problem of assessing similarities in the composition of different metallic alloys, using the laser-induced breakdown spectroscopy technique. The possibility of determining the degree of similarity through the use of artificial neural networks and self-organizing maps is discussed. As an example, we present a case study involving the comparison of two historical brass samples, very similar in their composition. The results of the paper can be extended to many other situations, not necessarily associated with cultural heritage and archeological studies, where objects with similar composition have to be compared. - Highlights: • A method for assessing the similarity of materials analyzed by LIBS is proposed. • Two very similar fragments of historical brass were analyzed. • Using a simple artificial neural network the composition of the two alloys was determined. • The composition of the two brass alloys was the same within the experimental error. • Using self-organizing maps, the probability of the alloys to have the same composition was assessed.

  4. Effect of high temperature annealing on ferromagnetism induced by energetic ion irradiation in FeRh alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kosugi, S.; Fujita, Nao; Matsui, T.; Hori, F. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Japan Atomic Energy Agency (JAEA-Takasaki), Takasaki, Gunma 370-1292 (Japan); Ishikawa, N.; Okamoto, Y. [Japan Atomic Energy Agency (JAEA-Tokai), Tokai, Ibaraki 319-1195 (Japan); Iwase, A., E-mail: iwase@mtr.osakafu-u.ac.j [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2011-05-01

    Effects of thermal annealing on ion-irradiation induced ferromagnetism of Fe-50at.%Rh bulk alloy and the related structural change were investigated by means of superconducting quantum interference device (SQUID) and extended X-ray absorption fine structure (EXAFS), respectively. Depending on the annealing temperature from 100 to 500 {sup o}C, the magnetization induced by 10 MeV iodine ion irradiation and the lattice structure of the alloy were remarkably changed. After 500 {sup o}C annealing, the magnetization and the lattice ordering of the alloy become similar to the states before the irradiation. The experimental result indicates that the thermal relaxation of irradiation-induced atomic disordering dominates the magnetic state of ion-irradiated Fe-50at.% Rh alloy.

  5. Inducing TiAl3 in titanium alloys by electric pulse heat treatment improves mechanical properties

    International Nuclear Information System (INIS)

    Highlights: ► EPH treatment is employed to modulate microstructure of titanium alloy. ► TiAl3 precipitations induce an unusual refinement behavior for alpha plates. ► Diffusion and accumulation of Al atoms attribute the formation mechanism of TiAl3. ► The susceptibility to adiabatic shear banding is reduced significantly. - Abstract: Titanium alloy is well known with its susceptibility to adiabatic shear banding, which limits its application unavoidably. In the current study, the electric pulse heat treatment is employed to modulate lamellar microstructure of a newly developed titanium alloy Ti–6Al–4V–4Zr–Mo. It is found that novel lath-shaped and nano-sized TiAl3 precipitations are formed within alpha plates. Diffusion of Al atoms, promoted by the electric pulse, and subsequent local atom accumulation attribute the underlying formation mechanism of TiAl3, which induces an unusual refinement effect by dividing the alpha plates into much tinier pieces, and provides an intriguing effect to dramatically reduce the susceptibility to adiabatic shear banding.

  6. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations CCF-LIBS calculated by CF-LIBS and the certified concentrations Ccertified were very close

  7. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    Science.gov (United States)

    Achouri, M.; Baba-Hamed, T.; Beldjilali, S. A.; Belasri, A.

    2015-09-01

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations C CF-LIBS calculated by CF-LIBS and the certified concentrations C certified were very close.

  8. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Achouri, M.; Baba-Hamed, T.; Beldjilali, S. A., E-mail: sidahmed.beldjilali@univ-usto.dz; Belasri, A. [Université des Sciences et de la Technologie d’Oran Mohamed Boudiaf USTO-MB, LPPMCA (Algeria)

    2015-09-15

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations C{sub CF-LIBS} calculated by CF-LIBS and the certified concentrations C{sub certified} were very close.

  9. Effect of strain-induced precipitation on dynamic recrystallization in Mg–Al–Sn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kabir, Abu Syed Humaun, E-mail: abu.kabir@mail.mcgill.ca; Sanjari, Mehdi; Su, Jing; Jung, In-Ho; Yue, Stephen

    2014-10-20

    Two different amounts of tin (Sn) were added to a Mg–3 wt% Al binary alloy to form different amounts of precipitates during hot deformation. The thermodynamic modeling software, FactSage{sup ™}, was used to calculate the amounts of Sn to generate the desired relative levels of precipitation. The alloys were deformed at four different temperatures and three different strain rates to generate different amounts of precipitates. The objective was to study the effect of these precipitates on dynamic recrystallization. The results indicated that the formation of strain-induced precipitates is a function of deformation temperature, strain, and strain rate. The findings also revealed that higher amounts of precipitates reduced the volume fraction of dynamic recrystallization and refined the dynamically recrystallized grain size.

  10. Oxygen-induced Y surface segregation in a CuPdY ternary alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tafen, D N.; Miller, J B.; Dogan, O N.; Baltrus, J P.; Kondratyuk, P

    2013-01-01

    We present a comprehensive theoretical and experimental study of the segregation behavior of the ternary alloy CuPdY in vacuum (i.e., the clean surface) and in the presence of oxygen. Theoretical prediction shows that for clean surface, yttrium will substitute first for Cu and then for Pd at the subsurface lattice site before segregating to the surface where it substitutes for Cu. XRD characterization of the surface of CuPdY indicates the presence of two major phases, B2 CuPd and Pd{sub 3}Y. In the presence of adsorbed oxygen, theory predicts that Y preferentially occupies surface sites due to its stronger oxygen affinity compared to Cu and Pd. XPS experiments confirm the computational results in the adsorbed oxygen case, showing that surface segregation of yttrium is induced by the formation of Y-oxides at the top-surface of the alloy.

  11. Analytical model of radiation-induced precipitation at the surface of dilute binary alloy

    International Nuclear Information System (INIS)

    Growth of precipitate layer at the foil surface of an undersaturated binary alloy under uniform irradiation is treated analytically. Analytical expressions for the layer growth rate, layer thickness limit and final component concentrations in the matrix are derived for coherent and incoherent precipitate-matrix interfaces. It is shown that the high temperature limit of radiation-induced precipitation is the same for both types of interfaces, whereas layer thickness limits are different. A parabolic law of the layer growth predicted for both types of interfaces is in agreement with experimental data on γ'-phase precipitation at the surface of Ni-Si dilute alloys under ion irradiation. Effect of sputtering on the precipitation rate and on the low temperature limit of precipitation under ion irradiation is discussed

  12. Laser-induced microstructural development and phase evolution in magnesium alloy

    International Nuclear Information System (INIS)

    Highlights: • Secondary phase evolution caused by laser processing was firstly reported. • Microstructure development was controlled by heat flow thermodynamics and kinetics. • Solid-state transformation resulted in submicron and nano-scale precipitates. • Cluster-shaped particles in overlapped region were due to precipitation coarsening. • Properties of materials can be tailored selectively by laser processing. -- Abstract: Secondary phase plays an important role in determining microstructures and properties of magnesium alloys. This paper focuses on laser-induced microstructure development and secondary phase evolution in AZ91D Mg alloy studied by SEM, TEM and EDS analyses. Compared to bulk shape and lamellar structure of the secondary phase in as-received cast material, rapid-solidified microstructures with various morphologies including nano-precipitates were observed in laser melt zone. Formation mechanisms of microstructural evolution and effect of phase development on surface properties were further discussed

  13. AN EVALUATION OF HYDROGEN INDUCED CRACKING SUSCEPTIBILITY OF TITANIUM ALLOYS IN US HIGH-LEVEL NUCLEAR WASTE REPOSITORY ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    G. De; K. Mon; G. Gordon; D. Shoesmith; F. Hua

    2006-02-21

    This paper evaluates hydrogen-induced cracking (HIC) susceptibility of titanium alloys in environments anticipated in the Yucca Mountain nuclear waste repository with particular emphasis on the. effect of the oxide passive film on the hydrogen absorption process of titanium alloys being evaluated. The titanium alloys considered in this review include Ti 2, 5 , 7, 9, 11, 12, 16, 17, 18, 24 and 29. In general, the concentration of hydrogen in a titanium alloy can increase due to absorption of atomic hydrogen produced from passive general corrosion of that alloy or galvanic coupling of it to a less noble metal. It is concluded that under the exposure conditions anticipated in the Yucca Mountain repository, the HIC of titanium drip shield will not occur because there will not be sufficient hydrogen in the metal even after 10,000 years of emplacement. Due to the conservatisms adopted in the current evaluation, this assessment is considered very conservative.

  14. AN EVALUATION OF HYDROGEN INDUCED CRACKING SUSCEPTIBILITY OF TITANIUM ALLOYS IN US HIGH-LEVEL NUCLEAR WASTE REPOSITORY ENVIRONMENTS

    International Nuclear Information System (INIS)

    This paper evaluates hydrogen-induced cracking (HIC) susceptibility of titanium alloys in environments anticipated in the Yucca Mountain nuclear waste repository with particular emphasis on the. effect of the oxide passive film on the hydrogen absorption process of titanium alloys being evaluated. The titanium alloys considered in this review include Ti 2, 5 , 7, 9, 11, 12, 16, 17, 18, 24 and 29. In general, the concentration of hydrogen in a titanium alloy can increase due to absorption of atomic hydrogen produced from passive general corrosion of that alloy or galvanic coupling of it to a less noble metal. It is concluded that under the exposure conditions anticipated in the Yucca Mountain repository, the HIC of titanium drip shield will not occur because there will not be sufficient hydrogen in the metal even after 10,000 years of emplacement. Due to the conservatisms adopted in the current evaluation, this assessment is considered very conservative

  15. Synthesis of the C22-C40 Domain of the Azaspiracids.

    Science.gov (United States)

    Zhang, Zhigao; Chen, Yong; Adu-Ampratwum, Daniel; Okumu, Antony Akura; Kenton, Nathaniel T; Forsyth, Craig J

    2016-04-15

    An efficient synthesis of the C22-C40 domain of the azaspiracids is described. The synthetic route features a Nozaki-Hiyama-Kishi (NHK) coupling and chelation controlled Mukaiyama aldol reaction to access an acyclic intermediate and a double-intramolecular-hetero-Michael addition (DIHMA) to provide the FG-ring system bridged ketal. PMID:27043010

  16. 26 CFR 1.381(c)(22)-1 - Successor life insurance company.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 4 2010-04-01 2010-04-01 false Successor life insurance company. 1.381(c)(22)-1... company. (a) Carryover requirement. If in a taxable year beginning after December 31, 1957, a distributor or transferor corporation which is an insurance company is acquired by a corporation which is...

  17. Coherent potential approximation treatment of the Sm valence transition in SmS induced by alloying

    International Nuclear Information System (INIS)

    The Sm valence transition, similar to the pressure-induced transition in pure SmS, has been observed in a large number of cases by substituting a trivalent rare earth, B, for Sm, thereby forming isostructural alloys with a lattice constant smaller than that of semiconducting SmS. Such substitutions are expected to exert a 'chemical' pressure which simulates the external pressure. However, divalent substitutions (Yb, Eu and Ca), although having a favourable 'size' factor, do not induce any valence transition. Accordingly, band structure effects, essentially due to the relative position of the conduction bands of SmS and BS, should also be taken into consideration. In order to clarify the role which the lattice constant and the electronic structure play in the valence transition, these alloys have been studied using the coherent potential approximation (CPA) including both the crystal field effect and the Coulomb interaction between localised and itinerant states as driving mechanisms. For Sm, the 'homogeneous' picture is considered, each Sm site having the average valence; then the Smsub(1-x)Bsub(x)S system is reduced to a binary alloy. Charge transfer between the f states of Sm and the alloy conduction band (i.e. Sm valence change) is determined self-consistently. The calculations are consistent with the experimental behaviour and allow us to understand qualitatively the variation of the critical concentration xsub(c) for the transition as a function of the difference Δa between the lattice parameters of SmS and BS. (author)

  18. Radiation-Induced Segregation and Phase Stability in Candidate Alloys for the Advanced Burner Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gary S. Was; Brian D. Wirth

    2011-05-29

    Major accomplishments of this project were the following: 1) Radiation induced depletion of Cr occurs in alloy D9, in agreement with that observed in austenitic alloys. 2) In F-M alloys, Cr enriches at PAG grain boundaries at low dose (<7 dpa) and at intermediate temperature (400°C) and the magnitude of the enrichment decreases with temperature. 3) Cr enrichment decreases with dose, remaining enriched in alloy T91 up to 10 dpa, but changing to depletion above 3 dpa in HT9 and HCM12A. 4) Cr has a higher diffusivity than Fe by a vacancy mechanism and the corresponding atomic flux of Cr is larger than Fe in the opposite direction to the vacancy flux. 5) Cr concentration at grain boundaries decreases as a result of vacancy transport during electron or proton irradiation, consistent with Inverse Kirkendall models. 6) Inclusion of other point defect sinks into the KLMC simulation of vacancy-mediated diffusion only influences the results in the low temperature, recombination dominated regime, but does not change the conclusion that Cr depletes as a result of vacancy transport to the sink. 7) Cr segregation behavior is independent of Frenkel pair versus cascade production, as simulated for electron versus proton irradiation conditions, for the temperatures investigated. 8) The amount of Cr depletion at a simulated planar boundary with vacancy-mediated diffusion reaches an apparent saturation value by about 1 dpa, with the precise saturation concentration dependent on the ratio of Cr to Fe diffusivity. 9) Cr diffuses faster than Fe by an interstitial transport mechanism, and the corresponding atomic flux of Cr is much larger than Fe in the same direction as the interstitial flux. 10) Observed experimental and computational results show that the radiation induced segregation behavior of Cr is consistent with an Inverse Kirkendall mechanism.

  19. Characteristics of radioactivities induced in aluminum alloys and the effects due to those major and minor components

    International Nuclear Information System (INIS)

    In order to search the usefulness of aluminum alloys as a material for an accelerator and its surrounding apparatus, the characteristics of radioactivities induced in several aluminum alloys (AA 1230, AA 2219, JIS 5052, AA 6063 and AA 7079) and stainless steel (SUS 304) irradiated for a long time with high energy bremsstrahlung have been studied fundamentally and compared with each other. After the concentrations of major alloying elements and impurities in the above samples were determined by means of photon-activation, proton-activation and emission spectrochemical analyses, they were irradiated with 30 and 200 MeV bremsstrahlung. As the results, it was proved that the intensities of radioactivities induced in the aluminum alloys are greatly affected by those major and minor components, but are remarkably lower than that in the stainless steel. (author)

  20. Laser-induced diffusion decomposition in Fe–V thin-film alloys

    International Nuclear Information System (INIS)

    Highlights: • Irradiation of an Fe–V alloy by femtosecond laser triggers diffusion decomposition. • The decomposition occurs with strongly enhanced (∼4 orders) atomic diffusivity. • This anomaly is associated with the metallic glassy state achievable under laser quenching. • The ultrafast diffusion decomposition is responsible for laser-induced ferromagnetism. - Abstract: We investigate the origin of ferromagnetism induced in thin-film (∼20 nm) Fe–V alloys by their irradiation with subpicosecond laser pulses. We find with Rutherford backscattering that the magnetic modifications follow a thermally stimulated process of diffusion decomposition, with formation of a-few-nm-thick Fe enriched layer inside the film. Surprisingly, similar transformations in the samples were also found after their long-time (∼103 s) thermal annealing. However, the laser action provides much higher diffusion coefficients (∼4 orders of magnitude) than those obtained under standard heat treatments. We get a hint that this ultrafast diffusion decomposition occurs in the metallic glassy state achievable in laser-quenched samples. This vitrification is thought to be a prerequisite for the laser-induced onset of ferromagnetism that we observe

  1. A study on the behavior of boron in iron-base alloys by neutron induced autoradiography

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jin Sung; Rhee, Chang Kyu; Cho, Hae Dong; Han, Chang Hee; Lee, Chang Hee; Jung, Jung Hwan; Kim, Yi Kyung; Lee, Yong Bok

    2001-02-01

    Boron is widely utilized in steel or alloy making to improve certain properties. However, due to its lightness boron is difficult to detect or characterize its behavior even through TEM/EDS or EELS techniques. Although many companies recognize the beneficial effects of boron, the role or mechanism of the boron is not yet clearly understood. Therefore it is required to develop the autoradiography technique to elucidate the boron behavior in alloys. As the only institute operating research reactor in the country, it would be the responsibility of the institute to develop the technique and provide it to the industries. Quantitative analyses of boron in type 316 L stainless steel by neutron induced autoradiography was attempted in this study. Nine experimental reference alloys with different amount of boron were prepared and reliable chemical composition data were obtained. Autoradiographs of reference materials with three different neutron fluences ( 1.9 10{sup 13}, 1.9 10{sup 14} and 1.9 10{sup 15}/cm{sup 2} ) were obtained and a trial calibration curve of boron content vs. track density was acquired.

  2. Quantitative observations of hydrogen-induced, slow crack growth in a low alloy steel

    Science.gov (United States)

    Nelson, H. G.; Williams, D. P.

    1973-01-01

    Hydrogen-induced slow crack growth, da/dt, was studied in AISI-SAE 4130 low alloy steel in gaseous hydrogen and distilled water environments as a function of applied stress intensity, K, at various temperatures, hydrogen pressures, and alloy strength levels. At low values of K, da/dt was found to exhibit a strong exponential K dependence (Stage 1 growth) in both hydrogen and water. At intermediate values of K, da/dt exhibited a small but finite K dependence (Stage 2), with the Stage 2 slope being greater in hydrogen than in water. In hydrogen, at a constant K, (da/dt) sub 2 varied inversely with alloy strength level and varied essentially in the same complex manner with temperature and hydrogen pressure as noted previously. The results of this study provide support for most of the qualitative predictions of the lattice decohesion theory as recently modified by Oriani. The lack of quantitative agreement between data and theory and the inability of theory to explain the observed pressure dependence of slow crack growth are mentioned and possible rationalizations to account for these differences are presented.

  3. Multiscale model of global inner-core anisotropy induced by hcp-alloy plasticity

    CERN Document Server

    Lincot, A; Deguen, R; Merkel, Sébastien

    2016-01-01

    $\\bullet$ Multiscale model of inner-core anisotropy produced by hcp alloy deformation$\\bullet$ 5 to 20% single-crystal elastic anisotropy and plastic deformation by pyramidal slip $\\bullet$ Low-degree inner-core formation model with faster crystallization at the equatorThe Earth's solid inner-core exhibits a global seismic anisotropy of several percents. It results from a coherent alignment of anisotropic Fe-alloy crystals through the inner-core history that can be sampled by present-day seismic observations. By combining self-consistent polycrystal plasticity, inner-core formation models, Monte-Carlo search for elastic moduli, and simulations of seismic measurements, we introduce a multiscale model that can reproduce a global seismic anisotropy of several percents aligned with the Earth's rotation axis. Conditions for a successful model are an hexagonal-close-packed structure for the inner-core Fe-alloy, plastic deformation by pyramidal \\textless{}c+a\\textgreater{} slip, and large-scale flow induced by a low...

  4. Various categories of defects after surface alloying induced by high current pulsed electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Dian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Tang, Guangze, E-mail: oaktang@hit.edu.cn [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Gu, Le [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Mingren [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-10-01

    Highlights: • Four kinds of defects are found during surface alloying by high current electron beam. • Exploring the mechanism how these defects appear after irradiation. • Increasing pulsing cycles will help to get good surface quality. • Choosing proper energy density will increase surface quality. - Abstract: High current pulsed electron beam (HCPEB) is an attractive advanced materials processing method which could highly increase the mechanical properties and corrosion resistance. However, how to eliminate different kinds of defects during irradiation by HCPEB especially in condition of adding new elements is a challenging task. In the present research, the titanium and TaNb-TiW composite films was deposited on the carburizing steel (SAE9310 steel) by DC magnetron sputtering before irradiation. The process of surface alloying was induced by HCPEB with pulse duration of 2.5 μs and energy density ranging from 3 to 9 J/cm{sup 2}. Investigation of the microstructure indicated that there were several forms of defects after irradiation, such as surface unwetting, surface eruption, micro-cracks and layering. How the defects formed was explained by the results of electron microscopy and energy dispersive spectroscopy. The results also revealed that proper energy density (∼6 J/cm{sup 2}) and multi-number of irradiation (≥50 times) contributed to high quality of alloyed layers after irradiation.

  5. Origin of intergranular embrittlement of Al alloys induced by Na and Ca segregation: Grain boundary weakening

    International Nuclear Information System (INIS)

    Using a first-principles computational tensile test, we show that the ideal tensile strength of an Al grain boundary (GB) is reduced with both Na and Ca GB segregation. We demonstrate that the fracture occurs in the GB interface, dominated by the break of the interfacial bonds. Experimentally, we further show that the presence of Na or Ca impurity, which causes intergranular fracture, reduces the ultimate tensile strength when embrittlement occurs. These results suggest that the Na/Ca-induced intergranular embrittlement of an Al alloy originates mainly from the GB weakening due to the Na/Ca segregation

  6. Transmutation-induced embrittlement of V-Ti-Ni and V-Ni alloys in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Ohnuki, S.; Takahashi, H. [Hokkaido Univ., Sapparo (Japan); Garner, F.A. [Pacific Northwest National Laboratory, Richland, WA (United States); Pawel, J.E. [Oak Ridge National Laboratory, TN (United States)] [and others

    1996-04-01

    Vanadium, V-1Ni, V-10Ti and V-10Ti-1Ni (at %) were irradiated in HFIR to doses ranging from 18 to 30 dpa and temperatures between 300 and 600C. Since the irradiation was conducted in a highly thermalized neutron spectrum without shielding against thermal neutrons, significant levels of chromium (15-22%) were formed by transmutation. The addition of such large chromium levels strongly elevated the ductile to brittle transition temperature. At higher irradiation temperatures radiation-induced segregation of transmutant Cr and solute Ti at specimen surfaces leads to strong increases in the density of the alloy.

  7. Dependence of stress-induced omega transition and mechanical twinning on phase stability in metastable β Ti–V alloys

    International Nuclear Information System (INIS)

    Tensile properties and deformation microstructures of a series of binary β Ti–16–22V alloys have been investigated. The results show that the plastic deformation mode changes from the plate-like stress-induced ω phase transformation with a special habit plane of (− 5052)ω//(3 − 3 − 2)β to (332)<113> type deformation twinning with increasing the content of vanadium in the β Ti–16–22 wt.% V alloys. The plate-like stress-induced ω phase has a special orientation relationship with the β phase matrix, i.e., [110]β//[− 12 − 10]ω, (3 − 3 − 2)β//(− 5052)ω and (− 55 − 4)β//(30 − 31)ω. The alloys plastically deformed by stress-induced ω phase transformation exhibit relatively higher yield strength than those deformed via (332)<113> type deformation twinning. It can be concluded that the stability of β phase plays a significant role in plastic deformation mode, i.e., stress-induced ω phase transformation or (332)<113> type deformation twinning, which governs the mechanical property of the β Ti–16–22 wt.% V alloys. - Highlights: • Tensile properties and deformed microstructures of β Ti–16–22V alloys were studied. • Stress-induced ω phase transformation and (332)<113> twinning occur in the alloys. • Stability of β phase plays a significant role in plastic deformation mode. • Plastic deformation mode governs the mechanical property of the alloys

  8. Magnetically induced electrodeposition of Zn–Ni alloy coatings and their corrosion behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Vaishaka R. [Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar 575025, Mangalore, Karnataka (India); Bangera, Kasturi V. [Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar 575025, Mangalore, Karnataka (India); Electrochemistry Research Laboratory, Department of Physics, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar, 575025, Mangalore, Karnataka (India); Hegde, A. Chitharanjan, E-mail: hegdeac@rediffmail.com [Electrochemistry Research Laboratory, Department of Chemistry, National Institute of Technology Karnataka, NITK, Surathkal, Srinivasnagar 575025, Mangalore, Karnataka (India)

    2013-11-15

    The less magnetic features of Zn–Ni alloy compared to Fe–Ni and Fe–Co alloys made it interesting to develop them under the influence of applied magnetic field. In this regard, the effects of a magnetic field (B) applied in a direction parallel and perpendicular to the nominal current, during electrodeposition process of Zn–Ni alloy have been investigated by means of X-ray diffraction and EDX analysis. The modification of crystal orientation by superimposition of a varying magnetic field is studied for alloys of constant nickel content (8 a %.), deposited at optimal current density (j) of 3.0 A dm{sup −2}. The effect of magnetic field on crystallographic orientation and hence the corrosion behaviors of the coatings were studied. The preferential orientations (101) and (002) of the zinc phase and (330) γ-Ni{sub 5}Zn{sub 21} phase are always favored to exist with parallel and perpendicular magnetic field. The preferential (321) γ-Ni{sub 5}Zn{sub 21} orientation is found to be the characteristic of perpendicular magnetic field. Further, Zn (100) orientation is found to be non-responsive to the effect of parallel magnetic field. The coatings developed using perpendicular magnetic field is more corrosion resistant compare to that for parallel magnetic field. This is attributed to the additional (321) γ-Ni{sub 5}Zn{sub 21} orientations. The changes in the phase structure of the coatings deposited at different magnetic field are attributed to the effect caused by the magnetic convection induced in the electrolytic solution, called MHD effect (magneto-hydrodynamic effect). The chemical composition of the alloy was found to be same in both natural and magnetically induced deposition due to constant Ni content in the bath. The variation in the surface morphology of the coatings was studied by scanning electron microscopy (SEM). The Zn–Ni alloy coating deposited at 0.8 T perpendicular B showed the highest corrosion resistance (with corrosion rate=0.26×10{sup

  9. Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots

    Science.gov (United States)

    Adegoke, Oluwasesan; Park, Enoch Y.

    2016-06-01

    The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27–61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72–93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying.

  10. Microstructures, mechanical properties and corrosion resistance of Hastelloy C22 coating produced by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qin-Ying; Zhang, Yang-Fei [Department of Materials Science and Engineering, HEDPS, Center for Applied Physics and Technology, LTCS, College of Engineering, Peking University, Beijing 100871 (China); Bai, Shu-Lin, E-mail: slbai@pku.edu.cn [Department of Materials Science and Engineering, HEDPS, Center for Applied Physics and Technology, LTCS, College of Engineering, Peking University, Beijing 100871 (China); Liu, Zong-De [Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education, North China Electric Power University, Beijing 102206 (China)

    2013-03-15

    Highlights: ► Hastelloy C22 coatings were prepared by diode laser cladding technique. ► Higher laser speed resulted in smaller grain size. ► Size-effect played the key role in the hardness measurements by different ways. ► Coating with higher laser scanning speed displayed higher nano-scratch resistance. ► Small grain size was beneficial for improvement of coating corrosion resistance. -- Abstract: The Hastelloy C22 coatings H1 and H2 were prepared by laser cladding technique with laser scanning speeds of 6 and 12 mm/s, respectively. Their microstructures, mechanical properties and corrosion resistance were investigated. The microstructures and phase compositions were studied by metallurgical microscope, scanning electron microscope and X-ray diffraction analysis. The hardness and scratch resistance were measured by micro-hardness and nanoindentation tests. The polarization curves and electrochemical impedance spectroscopy were tested by electrochemical workstation. Planar, cellular and dendritic solidifications were observed in the coating cross-sections. The coatings metallurgically well-bonded with the substrate are mainly composed of primary phase γ-nickel with solution of Fe, W, Cr and grain boundary precipitate of Mo{sub 6}Ni{sub 6}C. The hardness and corrosion resistance of steel substrate are significantly improved by laser cladding Hastelloy C22 coating. Coating H2 shows higher micro-hardness than that of H1 by 34% and it also exhibits better corrosion resistance. The results indicate that the increase of laser scanning speed improves the microstuctures, mechanical properties and corrosion resistance of Hastelloy C22 coating.

  11. Strain-induced Precipitation in Ti Micro-alloyed Interstitial-free Steel

    Institute of Scientific and Technical Information of China (English)

    Ya-jun HUI; Yang YU; Lin WANG; Chang WANG; Wen-yuan LI; Bin CHEN

    2016-01-01

    Stress relaxation method was carried out on a Ti micro-alloyed interstitial-free (IF)steel at the tempera-ture ranging from 800 to 1 000 ℃.The results show that the softening kinetics curves of deformed austenite can be divided into three stages.At the first stage,the stress has a sharp drop due to the onset of recrystallization.At the second stage,a plateau appears on the relaxation curves indicating the start and finish of strain-induced precipitation. At the third stage,the stress curves begin to descend again because of coarsening of precipitates.Precipitation-time-temperature (PTT)diagram exhibited a “C”shape,and the nose point of the PTT diagram is located at 900 ℃ and the start precipitation time of 10 s.The theoretical calculation shows that the strain-induced precipitates were con-firmed as almost pure TiC particles.The TiC precipitates were heterogeneously distributed in either a chain-like or cell-like manner observed by transmission electron microscopy (TEM),which indicates the precipitates nucleated on dislocations or dislocation substructures.In addition,a thermodynamic analytical model was presented to describe the precipitation in Ti micro-alloyed IF steel,which shows a good agreement between the experimental observation and the predictions of the model.

  12. Twinning-Induced Elasticity in NiTi Shape Memory Alloys

    Science.gov (United States)

    Birk, Thorsten; Biswas, Somjeet; Frenzel, Jan; Eggeler, Gunther

    2016-03-01

    Pseudoelasticity (PE) in shape memory alloys relies on the formation of stress-induced martensite during loading and on the reverse transformation during unloading. PE yields reversible strains of up to 8 % and is applied in applications such as medical implants, flexible eye glass frames, damping elements, and others. Unfortunately, PE shows a strong temperature dependence and thus can only be exploited within a relatively narrow temperature window. The present work focuses on a related process, which we refer to as twinning-induced elasticity (TIE). It involves the growth and shrinkage of martensite variants which are stabilized by dislocations, which are introduced by appropriate cold work. TIE yields reversible strains of the order of 3 %. The TIE effect does not suffer from the strong temperature dependence of PE. The weak temperature dependence of mechanical TIE properties makes TIE attractive for applications where temperature fluctuations are large. In the present work, we study the TIE effect focusing on Ni50Ti50 shape memory alloy wires. The degree of plastic pre-deformation of the initial material represents a key parameter of the ingot metallurgy processing route. It governs the exploitable recoverable strain, the apparent Young's modulus, and the widths of the mechanical hysteresis. Dynamic mechanical analysis is used to study the effects of pre-deformation on elementary microstructural processes which govern TIE.

  13. Twinning-Induced Elasticity in NiTi Shape Memory Alloys

    Science.gov (United States)

    Birk, Thorsten; Biswas, Somjeet; Frenzel, Jan; Eggeler, Gunther

    2016-06-01

    Pseudoelasticity (PE) in shape memory alloys relies on the formation of stress-induced martensite during loading and on the reverse transformation during unloading. PE yields reversible strains of up to 8 % and is applied in applications such as medical implants, flexible eye glass frames, damping elements, and others. Unfortunately, PE shows a strong temperature dependence and thus can only be exploited within a relatively narrow temperature window. The present work focuses on a related process, which we refer to as twinning-induced elasticity (TIE). It involves the growth and shrinkage of martensite variants which are stabilized by dislocations, which are introduced by appropriate cold work. TIE yields reversible strains of the order of 3 %. The TIE effect does not suffer from the strong temperature dependence of PE. The weak temperature dependence of mechanical TIE properties makes TIE attractive for applications where temperature fluctuations are large. In the present work, we study the TIE effect focusing on Ni50Ti50 shape memory alloy wires. The degree of plastic pre-deformation of the initial material represents a key parameter of the ingot metallurgy processing route. It governs the exploitable recoverable strain, the apparent Young's modulus, and the widths of the mechanical hysteresis. Dynamic mechanical analysis is used to study the effects of pre-deformation on elementary microstructural processes which govern TIE.

  14. Elemental redistribution in a nanocrystalline Ni-Fe alloy induced by high-pressure torsion

    International Nuclear Information System (INIS)

    Highlights: · Elemental distribution of a nc Ni-Fe alloy before and after high-pressure torsion. · The supersaturated Ni-Fe solid solution was stable under HPT. · C and S atoms further segregated to the remaining GBs during grain growth. · GB diffusion and the motion of defects facilitate the elemental redistribution. - Abstract: An electrochemically deposited nanocrystalline supersaturated face-centred-cubic Ni-21 at.% Fe alloy with an initial average grain size of ∼21 nm was processed using high-pressure torsion (HPT) that resulted in grain growth via grain rotation and coalescence to an average grain size of ∼53 nm. Atom probe tomography investigations revealed that the supersaturated Ni-Fe solid solution was stable under HPT and that C and S atoms, which are the major impurities in the material and segregated to the grain boundaries (GBs) of the as-deposited material, migrated from disappearing GBs to the remaining GBs during HPT. We propose that the elemental redistribution was facilitated by GB diffusion and the motion of a large volume of HPT-induced defects at the GB regions during the grain growth process. This elemental redistribution process is different from other HPT-induced elemental redistribution processes reported in the literature.

  15. C22:0- and C24:0-dihydroceramides confer mixed cytotoxicity in T-cell acute lymphoblastic leukemia cell lines.

    Directory of Open Access Journals (Sweden)

    Michael W Holliday

    Full Text Available We previously reported that fenretinide (4-HPR was cytotoxic to acute lymphoblastic leukemia (ALL cell lines in vitro in association with increased levels of de novo synthesized dihydroceramides, the immediate precursors of ceramides. However, the cytotoxic potentials of native dihydroceramides have not been defined. Therefore, we determined the cytotoxic effects of increasing dihydroceramide levels via de novo synthesis in T-cell ALL cell lines and whether such cytotoxicity was dependent on an absolute increase in total dihydroceramide mass versus an increase of certain specific dihydroceramides. A novel method employing supplementation of individual fatty acids, sphinganine, and the dihydroceramide desaturase-1 (DES inhibitor, GT-11, was used to increase de novo dihydroceramide synthesis and absolute levels of specific dihydroceramides and ceramides. Sphingolipidomic analyses of four T-cell ALL cell lines revealed strong positive correlations between cytotoxicity and levels of C22:0-dihydroceramide (ρ = 0.74-0.81, P ≤ 0.04 and C24:0-dihydroceramide (ρ = 0.84-0.90, P ≤ 0.004, but not between total or other individual dihydroceramides, ceramides, or sphingoid bases or phosphorylated derivatives. Selective increase of C22:0- and C24:0-dihydroceramide increased level and flux of autophagy marker, LC3B-II, and increased DNA fragmentation (TUNEL assay in the absence of an increase of reactive oxygen species; pan-caspase inhibition blocked DNA fragmentation but not cell death. C22:0-fatty acid supplemented to 4-HPR treated cells further increased C22:0-dihydroceramide levels (P ≤ 0.001 and cytotoxicity (P ≤ 0.001. These data demonstrate that increases of specific dihydroceramides are cytotoxic to T-cell ALL cells by a caspase-independent, mixed cell death mechanism associated with increased autophagy and suggest that dihydroceramides may contribute to 4-HPR-induced cytotoxicity. The targeted increase of specific acyl chain dihydroceramides

  16. Hydrodynamic instabilities of thin Au/Pd alloy film induced by tightly focused femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Kuchmizhak, Aleksandr, E-mail: ku4mijak@dvo.ru [Institute for Automation and Control Processes, Far Eastern Branch, Russian Academy of Science, 5 Radio str., Vladivostok 690041 (Russian Federation); Gurbatov, Stanislav; Nepomniaschiy, Aleksandr; Mayor, Aleksandr [Institute for Automation and Control Processes, Far Eastern Branch, Russian Academy of Science, 5 Radio str., Vladivostok 690041 (Russian Federation); Kulchin, Yuri; Vitrik, Oleg [Institute for Automation and Control Processes, Far Eastern Branch, Russian Academy of Science, 5 Radio str., Vladivostok 690041 (Russian Federation); Far Eastern Federal University, 8 Sukhanova Str., Vladivostok 690041 (Russian Federation); Makarov, Sergey [Lebedev Physical Institute, Moscow 119991 (Russian Federation); ITMO University, St. Petersburg 197101 (Russian Federation); Kudryashov, Sergey [Lebedev Physical Institute, Moscow 119991 (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409 Moscow (Russian Federation); Ionin, Andrey [Lebedev Physical Institute, Moscow 119991 (Russian Federation)

    2015-05-15

    Highlights: • Each type of laser-induced hydrodynamic instabilities results in the formation of corresponding frozen surface relief nanostructure: nanojets, nanocrowns or hybrid structures (a nanojet surrounded by a nanocrown). • The thickness of the metal film as well as the pulse energy were found to be the key parameters determining the type of the resulted surface structure. • Pd addition in the Au film results in the formation of the nanojets and the spherical droplets with a porous internal structure. - Abstract: We report on detailed experimental study of various nanoscale surface hydrodynamic instabilities on thin Au/Pd alloy films induced by tightly focused single femtosecond pulses. Each type of laser-induced hydrodynamic instabilities results in the formation of corresponding resolidified surface relief nanostructure: nanojet, nanocrown or hybrid structure (a nanojet surrounded by a nanocrown), where the hybrid structure is reported for the first time. Thickness of metal films, as well as the laser pulse energy, were found to be the key parameters determining the type of the resulting surface structures. Single nanojets were revealed to appear only on films with sub-100-nm thickness, while irradiation of thicker films (120–240 nm) leads to the formation of nanocrowns at near-threshold energies or hybrid structures at higher energies. The underlying formation mechanisms giving rise to all of these laser-induced nanostructures are also discussed.

  17. Deuterium ion irradiation induced precipitation in Fe–Cr alloy: Characterization and effects on irradiation behavior

    International Nuclear Information System (INIS)

    Highlights: • A new phase precipitated in Fe–Cr alloy after deuterium ion irradiation at 773 K. • B2 structure was proposed for the Cr-rich new phase. • Strain fields around the precipitate have been measured by GPA. • The precipitate decrease growth rate of dislocation loop under electron irradiation. - Abstract: A new phase was found to precipitate in a Fe–Cr model alloy after 58 keV deuterium ion irradiation at 773 K. The nanoscale radiation-induced precipitate was studied systematically using high resolution transmission electron microscopy (HRTEM), image simulation and in-situ ultrahigh voltage transmission electron microscopy (HVEM). B2 structure is proposed for the new Cr-rich phase, which adopts a cube-on-cube orientation relationship with regard to the Fe matrix. Geometric phase analysis (GPA) was employed to measure the strain fields around the precipitate and this was used to explain its characteristic 1-dimensional elongation along the 〈1 0 0〉 Fe direction. The precipitate was stable under subsequent electron irradiation at different temperatures. We suggest that the precipitate with a high interface-to-volume ratio enhances the radiation resistance of the material. The reason for this is the presence of a large number of interfaces between the precipitate and the matrix, which may greatly reduce the concentration of point defects around the dislocation loops. This leads to a significant decrease in the growth rate

  18. Surface nanocrystallization mechanism of a rare earth magnesium alloy induced by HVOF supersonic microparticles bombarding

    International Nuclear Information System (INIS)

    A nanostructured surface layer with a thickness up to 60 μm was produced on a rare earth Mg-Gd-Y magnesium alloy using a new process named HVOF-SMB (high velocity oxygen-fuel flame supersonic microparticles bombarding). The microstructural features of the treated surface at various depth of the deformed layer were characterized by optical microscopy (OM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) with an aim to reveal the formation mechanism. Results showed that three steps during grain refinement process were found, i.e., twinning dominates the plastic deformation and divides the coarse grains into finer twin platelets at the initial stage, stacking faults are generated and a number of dislocation slip systems are activated leading to the cross slips with increasing strain and strain rate, eventually high-density dislocation networks, dislocation cells and dislocation arrays are formed, which further subdivides the twin platelets and residual microbands into sub-microstructures. As a result, homogeneous nanostructure with a grain size of about 10-20 nm is formed through dynamic recrystallization in the topmost surface layer. Based on the experimental observations, a grain refinement mechanism induced by plastic deformation with higher strain rate during the HVOF-SMB treatment in the rare earth Mg-Gd-Y alloy was proposed.

  19. Corrosion tests of 316L and Hastelloy C-22 in simulated tank waste solutions

    Energy Technology Data Exchange (ETDEWEB)

    MJ Danielson; SG Pitman

    2000-02-23

    Both the 316L stainless steel and Hastelloy{reg_sign} C-22 gave satisfactory corrosion performance in the simulated test environments. They were subjected to 100 day weight loss corrosion tests and electrochemical potentiodynamic evaluation. This activity supports confirmation of the design basis for the materials of construction of process vessels and equipment used to handle the feed to the LAW-melter evaporator. BNFL process and mechanical engineering will use the information derived from this task to select material of construction for process vessels and equipment.

  20. Nd:YAG laser cladding of marine propeller with hastelloy C-22

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.D.; Kang, K.H.; Kim, J.N. [Dept. of Mechanical Engineering, Inha University, Yonghyundong 253, Namku, 402-751, Incheon (Korea)

    2004-09-01

    Nd:YAG laser cladding with automatic wire feeding (Hastelloy C-22) has been done to increase the lifetime of marine propellers made of HBsC1. The effects of processing parameters on the quality of clad layer have been investigated and clad layers have analyzed by optical microscopy and Vickers hardness tester. The method to overcome the drop transfer problem during the wire feeding has been introduced. A cladding speed that is too fast or too slow influenced the shape of clad. The good clad layer without cracks and with low dilution has been obtained with the optimum processing parameters. (orig.)

  1. Structural identification of sedimentary C21 and C22 highly branched isoprenoid alkanes

    OpenAIRE

    Sinninghe Damsté, J.S.; Baas, M.; Geenevasen, J.A.J.; Kenig, F.

    2005-01-01

    C21 and C22 highly branched isoprenoid (HBI) alkanes occurring in high relative abundance in lagoonal sediments of Abu Dhabi have been unambiguously identified as 2,6,10-trimethyl-7-(3-methylpentyl)dodecane and 3,7,11-trimethyl-6- (3-methylpentyl)tridecane, respectively, using NMR spectroscopy. A second C21 HBI isomer is tentatively identified as 3,7,11-trimethyl-6-(3-methylbutyl)tridecane, on the basis of comparison of its mass spectral fragmentation with those of fully identified HBIs. The ...

  2. Zirconium, calcium, and strontium contents in magnesium based biodegradable alloys modulate the efficiency of implant-induced osseointegration

    Directory of Open Access Journals (Sweden)

    Mushahary D

    2013-08-01

    Full Text Available Dolly Mushahary,1,2 Ragamouni Sravanthi,2 Yuncang Li,2 Mahesh J Kumar,1 Nemani Harishankar,4 Peter D Hodgson,1 Cuie Wen,3 Gopal Pande2 1Institute for Frontier Materials, Deakin University, Geelong, Australia; 2CSIR- Centre for Cellular and Molecular Biology, Hyderabad, India; 3Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Australia; 4National Institute of Nutrition (ICMR, Tarnaka, Hyderabad, India Abstract: Development of new biodegradable implants and devices is necessary to meet the increasing needs of regenerative orthopedic procedures. An important consideration while formulating new implant materials is that they should physicochemically and biologically mimic bone-like properties. In earlier studies, we have developed and characterized magnesium based biodegradable alloys, in particular magnesium-zirconium (Mg-Zr alloys. Here we have reported the biological properties of four Mg-Zr alloys containing different quantities of strontium or calcium. The alloys were implanted in small cavities made in femur bones of New Zealand White rabbits, and the quantitative and qualitative assessments of newly induced bone tissue were carried out. A total of 30 experimental animals, three for each implant type, were studied, and bone induction was assessed by histological, immunohistochemical and radiological methods; cavities in the femurs with no implants and observed for the same period of time were kept as controls. Our results showed that Mg-Zr alloys containing appropriate quantities of strontium were more efficient in inducing good quality mineralized bone than other alloys. Our results have been discussed in the context of physicochemical and biological properties of the alloys, and they could be very useful in determining the nature of future generations of biodegradable orthopedic implants. Keywords: osteoblasts, bone mineralization, corrosion, osseointegration, surface energy, peri-implant

  3. Semi-solid process of 2024 wrought aluminum alloy by strain induced melt activation

    Directory of Open Access Journals (Sweden)

    Surachai Numsarapatnuk

    2013-10-01

    Full Text Available The aim of this study is to develop a production process of a fine globular structure feedstock of the 2024 aluminumalloy suitable for subsequent semi-solid forming. The 2024 wrought aluminum alloy was first annealed to reduce the effect ofwork hardening. Then, strain was induced in the alloy by cold compression. After that the microstructural evolution duringpartial melting was investigated. The samples were subjected to full annealing at 415°C for 3 hrs prior to cold compression of40% reduction of area (RA with 3 mm/min strain rate. After that samples were partially melted at 620°C with varying holdingtime from 0 to 60 min followed by water quenching. The grain size and the average grain diameter of solid grains weremeasured using the linear intercept method. The globularization was interpreted in terms of shape factor. Liquid fraction andthe distribution of the eutectic liquid was also investigated. It was found that during partial melting, the globular morphologywas formed by the liquid wetting and fragmentation of high angle boundaries of recrystallized grains. The suitable semi-solidmicrostructure was obtained from a condition of full annealing, 40% cold working and partial melting at 620°C for 6 minholding time. The near globular grains obtained in the range of 0-60 min consisted of uniform spheroid grains with an averagegrain diameter ranged from 73 to 121 m, quenched liquid fraction was approximately 13–27% and the shape factor was greaterthan 0.6. At a holding time of less than 6 min, grain coarsening was dominant by the immigration of high-angle grainboundaries. At a longer holding time, liquid fraction increased and Ostwald ripening was dominant. The coarsening rateconstant for the 2024 Al alloy was 400.36 mm3.s-1. At a soaking time of 60 min, it was found that a minimum diameter differencewas 1.06% with coarsening index n=3 in a power law equation. The non-dendritic slug of 2024 alloy was rapid compressedinto a disc with 90%RA

  4. Stress induced martensite transformation in Co–28Cr–6Mo alloy during room temperature deformation

    International Nuclear Information System (INIS)

    The phase transformation and texture change of two Co–28Cr–6Mo alloys during room temperature deformation were studied by using the in-situ synchrotron X-ray diffraction. It is found that a slight difference in chemical compositions can significantly change the phase constitutions and the mechanical properties. For the material with less Ni, C and N (lower α-phase stability), increasing the grain size promotes the athermal martensite transformation during cooling. The kinetics of the Stress Induced Martensite (SIM) phase transformation may be more affected by the athermal martensite instead of the grain size of the α-phase. After deformation, similar textures are produced in samples regardless the differences in the initial structures such as the phase constitution and the grain size; while a relatively strong {111} texture and a weak {100} texture are produced in the α-phase, a {101¯1} fiber texture is gradually developed in the ε-phase during uniaxial tension

  5. Stress induced martensite transformation in Co–28Cr–6Mo alloy during room temperature deformation

    Energy Technology Data Exchange (ETDEWEB)

    Cai, S., E-mail: song_cai@fwmetals.com [Fort Wayne Metals Research Products Corporation, 9609 Ardmore Avenue, Fort Wayne, IN 46809 (United States); Daymond, M.R. [Department of Mechanical and Materials Engineering, Queen' s University, Nicol Hall, 60 Union Street, Kingston, Ontario, Canada K7L 3N6 (Canada); Ren, Y. [Advanced Photon Source, Argonne National Laboratory, 9700S. Cass Avenue, 433/D008, Argonne, IL 60439 (United States)

    2013-09-15

    The phase transformation and texture change of two Co–28Cr–6Mo alloys during room temperature deformation were studied by using the in-situ synchrotron X-ray diffraction. It is found that a slight difference in chemical compositions can significantly change the phase constitutions and the mechanical properties. For the material with less Ni, C and N (lower α-phase stability), increasing the grain size promotes the athermal martensite transformation during cooling. The kinetics of the Stress Induced Martensite (SIM) phase transformation may be more affected by the athermal martensite instead of the grain size of the α-phase. After deformation, similar textures are produced in samples regardless the differences in the initial structures such as the phase constitution and the grain size; while a relatively strong {111} texture and a weak {100} texture are produced in the α-phase, a {101"¯1} fiber texture is gradually developed in the ε-phase during uniaxial tension.

  6. Stress induced martensite at the crack tip in NiTi alloys during fatigue loading

    Directory of Open Access Journals (Sweden)

    E. Sgambitterra

    2014-10-01

    Full Text Available Crack tip stress-induced phase transformation mechanisms in nickel-titanium alloys (NiTi were analyzed by Digital Image Correlation (DIC, under fatigue loads. In particular, Single Edge Crack (SEC specimens, obtained from a commercial pseudoelastic NiTi sheet, and an ad-hoc experimental setup were used, for direct measurements of the near crack tip displacement field by the DIC technique. Furthermore, a fitting procedure was developed to calculate the mode I Stress Intensity Factor (SIF, starting from the measured displacement field. Finally, cyclic tensile tests were performed at different operating temperature, in the range 298-338 K, and the evolution of the SIF was studied, which revealed a marked temperature dependence.

  7. The mechanism of radiation-induced segregation in ferritic–martensitic alloys

    International Nuclear Information System (INIS)

    The mechanism of radiation-induced segregation in Fe–Cr alloys was modeled using the inverse Kirkendall mechanism and compared to experimental measurements over a range of temperatures, bulk Cr compositions, and irradiation dose. The model showed that over a large temperature range chromium was enriched at sinks by interstitial migration, and at very high temperatures it was depleted by diffusing opposite to the vacancy flux. Experimental results and model predictions were in good qualitative and quantitative agreement with regard to the temperature dependence of segregation and the crossover from Cr enrichment to Cr depletion. The inverse Kirkendall mechanism was also in agreement with experimental findings that observed a decreasing amount of Cr enrichment with increasing bulk Cr composition. The effects of solute drag were modeled within the inverse Kirkendall framework, but were unable to account for either the crossover from Cr enrichment to Cr depletion or the magnitudes of segregation measured in experiments

  8. Transformation mechanism of deformation - induced compact martensite in Fe-Ni-C alloys

    International Nuclear Information System (INIS)

    Compact deformation - induced martensite found in Fe - 25Ni - 0.66C alloys has been studied by using optical, electron and scanning electron microscopy. The compact martensite consists of a large number of martensites with different variants connected closely to form large bulk in which almost no residual austenite remains. Its formation process is by further growth of thin plates to form lenticular plates and possible crossing and coalesence to form bulky martensite. These growth and coalesence are through martensitic twinning or twinning domains during deformation which leads to various interactions between the plates including cross, insert, coalescence and conversion. The substructure of the martensite is a crisscross twinning net. The corresponding deformation modes of the austenite are also studied. (orig.)

  9. Quantification of stress-induced damage and post-fire response of 5083 aluminum alloy

    International Nuclear Information System (INIS)

    One of the major concerns regarding the use of lightweight materials in ship construction is the response of those materials to fire scenarios, including the residual structural performance after a fire event. This paper presents a study on creep damage evolution in 5083 marine-grade aluminum alloy and its impact on residual mechanical behavior. Tests conducted at 400 °C and pre-selected tensile stress levels were interrupted at target amplitudes of accumulated engineering creep strains to investigate the stress-induced damage using ex-situ characterization. Two-dimensional optical and electron microscopy and three-dimensional X-ray tomography were utilized on samples extracted from these test specimens to characterize the external and internal creep damage. The stress-induced damage is primarily manifested as cavitation and dynamic microstructural evolution. Cavitation morphology, orientation and grain structure evolution were investigated on three perpendicular sample surfaces. A 3D examination of the damage state provided consistent damage information to that obtained from the 2D analysis. The post-fire mechanical properties were also evaluated and linked to the microstructural change. The competing processes of cavitation and grain structure evolution were investigated to develop an understanding of the stress-induced damage associated with high temperature creep

  10. Sudden stress-induced transformation events during nanoindentation of NiTi shape memory alloys

    International Nuclear Information System (INIS)

    This study investigates the stress-induced formation of martensite during nanoindentation of an austenitic NiTi shape memory alloy, where stress-induced martensite is stable at room temperature. An individual grain with a [1 1 1] surface normal was selected for spherical ex situ and in situ nanoindentation in a scanning electron microscope. The in situ load–displacement curves show several pop-ins which occur concomitantly with the formation of traces around the contact zone between the indenter tip and the sample. These traces exhibit a threefold symmetry around the remnant indent. A detailed study of the indentation-induced surface relief by atomic force microscopy before and after shape recovery allows to identify the formation of six twinned martensite plates. Post-mortem microstructural characterization shows that these twinned martensite plates are growing as the applied load is increasing. The activation of the experimentally observed twinned martensite plates is rationalized by analytical calculations of resolved shear stress and mechanical interaction energy density. Finally, the in situ nanoindentation results in combination with the post-mortem microstructural characterization show that the most likely deformation mechanism responsible for pop-in events corresponds to sudden increases of the thicknesses of twinned martensite plates

  11. Chloride ion effect and alloying effect on dealloying-induced formation of nanoporous AuPt alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yan, E-mail: mse_wangy@ujn.edu.cn; Xu, Junling; Wu, Bo

    2013-07-01

    The dealloying of the rapidly solidified Al{sub 66}Au{sub 23.8}Pt{sub 10.2} precursor in the 5 wt.% HCl or 20 wt.% NaOH solution has been investigated using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and transmission electron microscopy, in order to clarify the chloride ion effect and alloying effect on the formation of nanoporous Au–Pt alloy. The Al{sub 66}Au{sub 23.8}Pt{sub 10.2} precursor is composed of a single Al{sub 2}Au-type intermetallic compound and only Au(Pt) solid solution can be identified in the as-dealloyed sample. The Pt addition can significantly refine the nanoporous structure during the dealloying of the Al{sub 66}Au{sub 23.8}Pt{sub 10.2} precursor either in the HCl or NaOH solution. Moreover, the alloying effect of Pt markedly exceeds the coarsening effect of chloride ion adsorption for the formation of nanoporous Au–Pt. The average ligament size is 5.2 ± 0.7 and 3.3 ± 0.4 nm for the nanoporous Au–Pt alloy obtained in the HCl and NaOH solution, respectively. In addition, electrochemical measurements including potentiodynamic polarization and cyclic voltammetry have also been performed on the Al{sub 66}Au{sub 23.8}Pt{sub 10.2} precursor.

  12. Perpendicular magnetization of Co2FeAl full-Heusler alloy films induced by MgO interface

    Science.gov (United States)

    Wen, Zhenchao; Sukegawa, Hiroaki; Mitani, Seiji; Inomata, Koichiro

    2011-06-01

    The perpendicular magnetization of Co2FeAl (CFA) full-Heusler alloy films was achieved in the structures of CFA/MgO and MgO/CFA with the perpendicular magnetic anisotropy energy density (KU) of 2-3×106 erg/cm3, which can be used as the perpendicular ferromagnetic electrodes of MgO-based magnetic tunnel junctions (MTJs) with high thermal stability at sub-50-nm dimension. The CFA thickness dependence of KU was investigated at different annealing temperatures, indicating that the perpendicular anisotropy of CFA is contributed by the interfacial anisotropy between CFA and MgO. This letter will open up a way for obtaining perpendicular magnetization of Co-based full-Heusler alloys, which is promising for further reduction in the critical current of current induced magnetization switching in MgO-based MTJ nanopillars with perpendicular full-Heusler alloy electrodes.

  13. Irradiation induced stress relaxation and high temperature deformation behavior of neutron irradiated Ti based shape memory alloys

    International Nuclear Information System (INIS)

    Several tools using Ti based shape memory alloys (SMA) such as SMA coupler, connector, jack system and in-vacuum gate valve, have been developed to promote the remote maintenance and the quick replacement technology for fusion core parts. Recently, irradiation induced stress relaxation (IISR) has become a concern for components of the fusion core. IISR may be a severe problem for SMAs as well as the structural materials in the fusion reactor. The IISR of TiNi SMA and TiPd high temperature shape memory alloys (HTSMA), which have both transformation temperatures and working temperatures 400 K higher than those of TiNi alloys, may be controlled by the migration of vacancies rather than interstitials. This mechanism facilitates restoration of the damaged state to normal state under irradiation. TiPd HTSMAs may be used to fabricate irradiation-resistant shape memory devices for temperatures up to 800 K if proper heat treatments can be developed. ((orig.))

  14. Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles

    Science.gov (United States)

    Wang, Jia X.; Adzic, Radoslav R.

    2009-03-24

    The present invention relates to methods for producing metal-coated palladium or palladium-alloy particles. The method includes contacting hydrogen-absorbed palladium or palladium-alloy particles with one or more metal salts to produce a sub-monoatomic or monoatomic metal- or metal-alloy coating on the surface of the hydrogen-absorbed palladium or palladium-alloy particles. The invention also relates to methods for producing catalysts and methods for producing electrical energy using the metal-coated palladium or palladium-alloy particles of the present invention.

  15. Hydrogen Embrittlement Susceptibility and Hydrogen-Induced Additive Stress of 7050 Aluminum Alloy Under Various Aging States

    Science.gov (United States)

    Qi, W. J.; Song, R. G.; Qi, X.; Li, H.; Wang, Z. X.; Wang, C.; Jin, J. R.

    2015-09-01

    Hydrogen embrittlement susceptibility of 7050 aluminum alloy under various aging states has been investigated by means of cathodic hydrogen permeation, slow strain rate test, hydrogen determinator, x-ray diffraction, and scanning electron microscope, and effect of hydrogen on atomic binding force of charged alloy has been calculated by free electron theory in this paper. Simultaneously, hydrogen-induced additive stress (σad) of 7050 aluminum alloy hydrogen charged with different current densities under various aging states have been investigated by flowing stress differential method. The results showed that hydrogen concentration of examined alloy increased with increasing charging time or current density under the same aging state. Hydrogen segregation occurred at grain boundaries which enlarged the crystal lattice constant, meanwhile, it reduced the average bonding energy and interatomic bonding force of the grain boundary atoms, thus resulting in hydrogen embrittlement; moreover, σad of 7050 aluminum alloy increased linearly with increasing hydrogen concentration under the same aging state, i.e., under aged: σad = -1.61 + 9.93 × 105 C H, peak aged: σad = -1.55 + 9.67 × 105 C H, over aged: σad = -0.16 + 9.35 × 105 C H, correspondingly, σad increased the susceptibility to hydrogen embrittlement ( I HE) further. Under the same charging condition, aging states had a great influence on σad and I HE, the under-aged state alloy was of the highest, the over-aged state alloy was of the lowest, and peak-aged was in the middle.

  16. Micromechanical modelling of stress-induced martensitic transformation in shape memory alloys

    International Nuclear Information System (INIS)

    Modeling the functional behavior of shape memory alloys (SMA) is a challenge for the development of industrial applications using these materials. Modern concepts developed in mechanics of materials are very well adapted to solve this problem. Due to the specific characteristic length scales involved in the SMA behavior several different models are developed to deal with the physical mechanisms which are responsible to the observed macroscopic behavior. The formation and growth of the different variants of martensite at the crystal level and granular structure and texture effects greatly affect the overall behavior and must be accounted. The possibility to induce several variants is considered for the definition of constitutive equations for a crystal of austenite undergoing a martensitic transformation. These equations are derived from a kinematical description of the strain mechanism and using thermodynamical concepts. At this point the more difficult aspect is the description of the different classes of interaction which are observed between martensite variants. The use of the interfacial operators technique leads to the definition of an interaction matrix in copper based and in NiTi SMAs. The building of strong intergranular stresses during the transformation in polycrystalline material is the second important point to deal with. We propose to determine these stresses using a scale transition method issued from the field theory. Considering each grain as a single crystal, the classical self-consistent framework allows to compute the macroscopic behavior according to the initial crystallographic texture of the alloy considered. This model is applied to superelastic behavior and non-isothermal loading. The evolution of different microstructural parameters are presented and discussed. Complex loading conditions are also described and transformation surfaces useful for structure analysis are computed. A finite element simulation of the behavior of thin film will be

  17. Journal of Nuclear Materials - Radiation-induced segregation and phase stability in ferritic-martensitic alloy T 91

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Zhijie [ORNL; Busby, Jeremy T [ORNL; Was, Gary S [ORNL; Jiao, Zhijie [University of Michigan

    2010-01-01

    Radiation-induced segregation in ferritic martensitic alloy T 91 was studied to understand the behavior of solutes as a function of dose and temperature. Irradiations were conducted using 2 MeV protons to doses of 1, 3, 7 and 10 dpa at 400 C. Radiation-induced segregation at prior austenite grain boundaries was measured, and various features of the irradiated microstructure were characterized, including grain boundary carbide coverage, the dislocation microstructure, radiation-induced precipitation and irradiation hardening. Results showed that Cr, Ni and Si segregate to prior austenite grain boundaries at low dose, but segregation ceases and redistribution occurs above 3 dpa. Grain boundary carbide coverage mirrors radiation-induced segregation. Irradiation induces formation of Ni Si Mn and Cu-rich precipitates that account for the majority of irradiation hardening. Radiation-induced segregation behavior is likely linked to the evolution of the precipitate and dislocation microstructures. 2010 Elsevier B.V. All rights reserved

  18. Preparation of AZ91D magnesium alloy semi-solid billet by new strain induced melt activated method

    Institute of Scientific and Technical Information of China (English)

    JIANG Ju-fu; LUO Shou-jing; ZOU Jing-xiang

    2006-01-01

    New strain induced melt activated (new SIMA) method for preparing AZ91D magnesium alloy semi-solid billet is introduced by applying equal channel angular extrusion into strain induced step in SIMA method, by which semi-solid billet with fine spheroidal grains and average grain size of 18 μm can be prepared. Furthermore, average grain size of semi-solid billet is reduced with increasing extrusion pass of AZ91D magnesium alloy obtained in ECAE process. By using semi-solid billet prepared by new SIMA, thixoforged magazine plates component with high mechanical properties such as yield strength of 201.4 MPa, ultimate tensile strength of 321.8 MPa and elongation of 15.3%, can be obtained.

  19. Magnetic-field-induced reverse transformation in a NiCoMnSn high temperature ferromagnetic shape memory alloy

    International Nuclear Information System (INIS)

    The magnetic field induced reverse martensitic transformation was studied in polycrystalline Ni40Co10Mn41Sn9 with a high martensitic transformation start temperature (Ms, about 410 K). The reverse transformation start temperature (As) dropped by about 34 K when exposed to a magnetic field of 7 T. At room temperature, the microstructure consisted of 14M martensite and γ phase. - Highlights: • The paper demonstrates a magnetic field induced reverse transformation (MFIRT) occurring at high temperature (above 373 K) in polycrystalline Ni40Co10Mn41Sn9. • This high temperature MFIRT, to our knowledge, not reported in the literature for Ni–Co–Mn–Sn and other metamagnetic shape memory alloys. • The study would be expected to extend the practical application of Ni–Co–Mn–Sn alloy

  20. Transformation-Induced Creep and Creep Recovery of Shape Memory Alloy

    OpenAIRE

    Pieczyska, Elzbieta A.; Hisaaki Tobushi; Kohei Takeda

    2012-01-01

    If the shape memory alloy is subjected to the subloop loading under the stress-controlled condition, creep and creep recovery can appear based on the martensitic transformation. In the design of shape memory alloy elements, these deformation properties are important since the deflection of shape memory alloy elements can change under constant stress. The conditions for the progress of the martensitic transformation are discussed based on the kinetics of the martensitic transformation for the ...

  1. Electron irradiation-induced mechanical property changes in reactor pressure vessel alloys

    International Nuclear Information System (INIS)

    High-energy electrons were used to study tensile property changes in simple Fe-Cu and Fe-Cu-Mn alloys irradiated at 288C. A comparison was made with neutron irradiation data on the same alloys. An apparent effect of alloy chemistry was observed in which the presence of Mn affected embrittlement differently for electron and neutron irradiation. Comparison of previous experimental studies with the present experimental results indicates that electrons may be more efficient than fast neutrons at producing embrittlement

  2. Electron irradiation-induced mechanical property changes in reactor pressure vessel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, D.E.; Rehn, L.E. [Argonne National Lab., IL (United States); Odette, G.R.; Lucas, G.E. [California Univ., Santa Barbara, CA (United States). Dept. of Mechanical Engineering

    1995-11-01

    High-energy electrons were used to study tensile property changes in simple Fe-Cu and Fe-Cu-Mn alloys irradiated at 288C. A comparison was made with neutron irradiation data on the same alloys. An apparent effect of alloy chemistry was observed in which the presence of Mn affected embrittlement differently for electron and neutron irradiation. Comparison of previous experimental studies with the present experimental results indicates that electrons may be more efficient than fast neutrons at producing embrittlement.

  3. Megaelectron volt ion beam-induced epitaxy of deposited silicon and germanium-silicon alloys on (100) silicon substrates

    International Nuclear Information System (INIS)

    Solid phase heteroepitaxial crystallization of GexSi1-x/(100) Si was induced by MeV ion bombardment while heating the substrate at low temperatures. Rutherford Backscatter Spectrometry (RBS), Ion Channeling, Secondary Ion Mass Spectroscopy (SIMS) and transmission electron microscopy (TEM) techniques were used to investigate the kinetics of the reordering process as well as characterize the strain in the resultant epitaxial layer. The epitaxial recrystallization of amorphous silicon and silicon-germanium layers on (100)silicon, deposited under medium (10-7 torr) vacuum conditions, was induced by 2.5 MeV Ar beam irradiation in the low temperature range of 200-400C. The regrowth follows an Arrhenius dependence with temperature and activation energies of ∼0.3 eV were determined for the regrowth of deposited Si and a Ge38Si62 alloy. Ion beam induced heteroepitaxy was found to be sensitive to interfacial contaminants. In addition, the resultant crystalline quality for Ge-rich alloys was poor after irradiation. Ion beam induced heteroepitaxy of MBE-deposited GexSi1-x/(100) Si, deposited under high vacuum conditions after strict interfacial preparation, resulted in layer-by-layer reordering for alloys up to 65 at. % Ge. Coherently strained epilayers were reported for ion beam annealed GeSi alloys with germanium concentration less than 15 at. %. The pseudomorphic epilayers were characterized by planar and axial channeling to measure the tetragonal distortion in the strained overlayers. Strained films, produced by MeV Ar bombardment while heating the substrate at temperatures as low as 300C, were observed to relax following extended furnace anneals at temperatures of 800-900C. Such results offer the possibility of extending defect-free growth of metastable strained layers to other lattice mismatched systems

  4. Relating field-induced shift in transition temperature to the kinetics of coexisting phases in magnetic shape memory alloys

    OpenAIRE

    Banerjee, A.; Dash, S.; Lakhani, Archana; Chaddah, P.; Chen, X; Ramanujan, R. V.

    2011-01-01

    In a magnetic shape memory alloy system, we vary composition following phenomenological arguments to tune macroscopic properties. We achieve significantly higher shift in austenite to martensitic phase transition temperature with magnetic field. This enhancement is accompanied by significant broadening of the transition and by field-induced arrest of kinetics, both of which are related to the dynamics of the coexisting phases. This reveals hitherto unknown interrelationship between different ...

  5. Atom probe study of the microstructural evolution induced by irradiation in Fe-Cu ferritic alloys and pressure vessel steels

    International Nuclear Information System (INIS)

    Pressure vessel steels used in pressurized water reactors are low alloyed ferritic steels. They may be prone to hardening and embrittlement under neutron irradiation. The changes in mechanical properties are generally supposed to result from the formation of point defects, dislocation loops, voids and/or copper rich clusters. However, the real nature of the irradiation induced-damage in these steels has not been clearly identified yet. In order to improve our vision of this damage, we have characterized the microstructure of several steels and model alloys irradiated with electrons and neutrons. The study was performed with conventional and tomographic atom probes. The well known importance of the effects of copper upon pressure vessel steel embrittlement has led us to study Fe-Cu binary alloys. We have considered chemical aging as well as aging under electron and neutron irradiations. The resulting effects depend on whether electron or neutron irradiations ar used for thus. We carried out both kinds of irradiation concurrently so as to compare their effects. We have more particularly considered alloys with a low copper supersaturation representative of that met with the French vessel alloys (0.1% Cu). Then, we have examined steels used on French nuclear reactor pressure vessels. To characterize the microstructure of CHOOZ A steel and its evolution when exposed to neutrons, we have studied samples from the reactor surveillance program. The results achieved, especially the characterization of neutron-induced defects have been compared with those for another steel from the surveillance program of Dampierre 2. All the experiment results obtained on model and industrial steels have allowed us to consider an explanation of the way how the defects appear and grow, and to propose reasons for their influence upon steel embrittlement. (author). 3 appends

  6. Bi-induced band gap reduction in epitaxial InSbBi alloys

    International Nuclear Information System (INIS)

    The properties of molecular beam epitaxy-grown InSb1−xBix alloys are investigated. Rutherford backscattering spectrometry shows that the Bi content increases from 0.6% for growth at 350 °C to 2.4% at 200 °C. X-ray diffraction indicates Bi-induced lattice dilation and suggests a zinc-blende InBi lattice parameter of 6.626 Å. Scanning electron microscopy reveals surface InSbBi nanostructures on the InSbBi films for the lowest growth temperatures, Bi droplets at intermediate temperatures, and smooth surfaces for the highest temperature. The room temperature optical absorption edge was found to change from 172 meV (7.2 μm) for InSb to ∼88 meV (14.1 μm) for InSb0.976Bi0.024, a reduction of ∼35 meV/%Bi

  7. Bi-induced band gap reduction in epitaxial InSbBi alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rajpalke, M. K.; Linhart, W. M.; Birkett, M.; Alaria, J.; Veal, T. D., E-mail: T.Veal@liverpool.ac.uk [Stephenson Institute for Renewable Energy and Department of Physics, School of Physical Sciences, University of Liverpool, Liverpool L69 7ZF (United Kingdom); Yu, K. M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Bomphrey, J. J.; Jones, T. S.; Ashwin, M. J., E-mail: M.J.Ashwin@warwick.ac.uk [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Sallis, S.; Piper, L. F. J. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States)

    2014-11-24

    The properties of molecular beam epitaxy-grown InSb{sub 1−x}Bi{sub x} alloys are investigated. Rutherford backscattering spectrometry shows that the Bi content increases from 0.6% for growth at 350 °C to 2.4% at 200 °C. X-ray diffraction indicates Bi-induced lattice dilation and suggests a zinc-blende InBi lattice parameter of 6.626 Å. Scanning electron microscopy reveals surface InSbBi nanostructures on the InSbBi films for the lowest growth temperatures, Bi droplets at intermediate temperatures, and smooth surfaces for the highest temperature. The room temperature optical absorption edge was found to change from 172 meV (7.2 μm) for InSb to ∼88 meV (14.1 μm) for InSb{sub 0.976}Bi{sub 0.024}, a reduction of ∼35 meV/%Bi.

  8. Irradiation-induced precipitation and mechanical properties of vanadium alloys at <430 C

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-09-01

    Recent attention to V-base alloys has focused on the effect of low-temperature (<430 C) irradiation on tensile and impact properties of V-4Cr-4Ti. In previous studies, dislocation channeling, which causes flow localization and severe loss of work-hardening capability, has been attributed to dense, irradiation-induced precipitation of very fine particles. However, efforts to identify the precipitates were unsuccessful until now. In this study, analysis by transmission electron microscopy (TEM) was conducted on unalloyed V, V-5Ti, V-3Ti-1Si, and V-4Cr-4Ti specimens that were irradiated at <430 C in conventional and dynamic helium charging experiments. By means of dark-field imaging and selected-area-diffraction analysis, the characteristic precipitates were identified to be (V,Ti{sub 1{minus}x})(C,O,N). In V-3Ti-1Si, precipitation of (V,Ti{sub 1{minus}x})(C,O,N) was negligible at <430 C, and as a result, dislocation channeling did not occur and work-hardening capability was high.

  9. Effect of alloying additions on the hydrogen-induced grain boundary embrittlement in iron.

    Science.gov (United States)

    Tian, Z X; Yan, J X; Hao, W; Xiao, W

    2011-01-12

    Using ab initio density functional theory calculations, we have investigated the influence of Mo, V and Pd on the H-induced grain boundary embrittlement in Fe. We find that, in the high impurity concentration systems, all of the three alloying elements facilitate H embrittlement at the Σ3 (111) [Formula: see text] grain boundary in Fe. The calculated binary effects of the H-X (X = Mo, V, Pd) couples are 0.063, 0.074 and 0.040 eV, respectively. On the other hand, in the large unit cell with low impurity concentration, both Mo and V can facilitate H embrittlement, and the binary effects of pairs are 0.152 and 0.164 eV, respectively. While Pd reduces the H embrittlement on the cohesion of the Fe grain boundary with the binary effect of - 0.1 eV. The H-X (X = Mo, V, Pd) interactions are interpreted by electronic structure analyses. PMID:21406825

  10. Effect of alloying additions on the hydrogen-induced grain boundary embrittlement in iron

    International Nuclear Information System (INIS)

    Using ab initio density functional theory calculations, we have investigated the influence of Mo, V and Pd on the H-induced grain boundary embrittlement in Fe. We find that, in the high impurity concentration systems, all of the three alloying elements facilitate H embrittlement at the Σ3 (111) [1 1-bar 0] grain boundary in Fe. The calculated binary effects of the H-X (X = Mo, V, Pd) couples are 0.063, 0.074 and 0.040 eV, respectively. On the other hand, in the large unit cell with low impurity concentration, both Mo and V can facilitate H embrittlement, and the binary effects of pairs are 0.152 and 0.164 eV, respectively. While Pd reduces the H embrittlement on the cohesion of the Fe grain boundary with the binary effect of - 0.1 eV. The H-X (X = Mo, V, Pd) interactions are interpreted by electronic structure analyses.

  11. Statistical Classification of Soft Solder Alloys by Laser-Induced Breakdown Spectroscopy: Review of Methods

    Science.gov (United States)

    Zdunek, R.; Nowak, M.; Pliński, E.

    2016-02-01

    This paper reviews machine-learning methods that are nowadays the most frequently used for the supervised classification of spectral signals in laser-induced breakdown spectroscopy (LIBS). We analyze and compare various statistical classification methods, such as linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), partial least-squares discriminant analysis (PLS-DA), soft independent modeling of class analogy (SIMCA), support vector machine (SVM), naive Bayes method, probabilistic neural networks (PNN), and K-nearest neighbor (KNN) method. The theoretical considerations are supported with experiments conducted for real soft-solder-alloy spectra obtained using LIBS. We consider two decision problems: binary and multiclass classification. The former is used to distinguish overheated soft solders from their normal versions. The latter aims to assign a testing sample to a given group of materials. The measurements are obtained for several laser-energy values, projection masks, and numbers of laser shots. Using cross-validation, we evaluate the above classification methods in terms of their usefulness in solving both classification problems.

  12. A layman's guide to radiation-induced deformation processes in zirconium alloys

    International Nuclear Information System (INIS)

    The fuel channel (comprising a pressure tube and a calandria tube fabricated from zirconium alloys) in a CANDU reactor undergoes shape changes because of radiation-induced deformation. This is a consequence of the microstructural modification arising from radiation damage produced by the fast-neutron flux. This report summarizes our current understanding of the physical processes responsible for the deformation. With the non-specialist reader in mind, the underlying mechanisms are described in a manner that avoids much of the associated technical terminology. Thus, the basic concepts of plasticity in a crystalline material are introduced and related to the various microstructural defects created during irradiation. In particular, the mechanisms of creep (a time-dependent strain activated by an applied stress) and growth (a time-dependent strain occurring in the absence of stress) are discussed in a non-technical language assisted by simple diagrams. Reference is made to both theoretical investigations (avoiding mathematical complexity) and experimental measurements. It is shown how the qualitative and quantitative knowledge can be used to derive a predictive model for reactor designers and operators. The current status of such a model is evaluated and suggestions for future improvements made

  13. Toward a better understanding of the hydrogen impact on the radiation induced growth of zirconium alloys

    International Nuclear Information System (INIS)

    Under neutron irradiation, recrystallized zirconium alloys, used as structural materials for Pressurized Water Reactor fuel assemblies, undergo stress-free growth which accelerates for high irradiation doses. This acceleration is correlated to the formation of c-component vacancy dislocation loops. Some feedbacks from neutron irradiations show that the in-service hydrogen pick-up could influence the fuel assembly radiation-induced elongation. 2 MeV proton irradiations were performed on as fabricated materials in M5®, recrystallized Zircaloy-4 and 350 wppm pre-hydrided M5®. The irradiations were conducted on a Tandem Accelerator (MIBL/University of Michigan) at 623 K up to four doses. For both grades, the c-component loops evolution with dose is examined and compared to the neutron irradiated microstructures. As observed under neutron irradiation, the c-loop density in Zy-4 is higher than in M5®. Moreover, TEM observations on 350 wppm pre-hydrided M5® show that c-loop density is higher than without pre-hydriding. It is also seen that c-loops are preferentially located in the surrounding of some delta-hydrides partially or fully dissolved. The role played by hydrogen in solid solution and as precipitated hydrides is discussed

  14. Toward a better understanding of the hydrogen impact on the radiation induced growth of zirconium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tournadre, L. [CEA-DEN, Section for Applied Metallurgy Research, 91191 Gif-sur-Yvette Cedex (France); Onimus, F., E-mail: fabien.onimus@cea.fr [CEA-DEN, Section for Applied Metallurgy Research, 91191 Gif-sur-Yvette Cedex (France); Béchade, J.-L. [CEA-DEN, Section for Applied Metallurgy Research, 91191 Gif-sur-Yvette Cedex (France); Gilbon, D. [CEA-DEN, Nuclear Material Department, 91191 Gif-sur-Yvette Cedex (France); Cloué, J.-M.; Mardon, J.-P. [AREVA AREVA NP SAS Fuel Business Unit 10, Rue Juliette Recamier, 69456 Lyon Cedex 06 (France); Feaugas, X. [LaSIE, FRE CNRS 3474, Université de La Rochelle, 17042 La Rochelle Cedex 1 (France)

    2013-10-15

    Under neutron irradiation, recrystallized zirconium alloys, used as structural materials for Pressurized Water Reactor fuel assemblies, undergo stress-free growth which accelerates for high irradiation doses. This acceleration is correlated to the formation of c-component vacancy dislocation loops. Some feedbacks from neutron irradiations show that the in-service hydrogen pick-up could influence the fuel assembly radiation-induced elongation. 2 MeV proton irradiations were performed on as fabricated materials in M5{sup ®}, recrystallized Zircaloy-4 and 350 wppm pre-hydrided M5{sup ®}. The irradiations were conducted on a Tandem Accelerator (MIBL/University of Michigan) at 623 K up to four doses. For both grades, the c-component loops evolution with dose is examined and compared to the neutron irradiated microstructures. As observed under neutron irradiation, the c-loop density in Zy-4 is higher than in M5{sup ®}. Moreover, TEM observations on 350 wppm pre-hydrided M5{sup ®} show that c-loop density is higher than without pre-hydriding. It is also seen that c-loops are preferentially located in the surrounding of some delta-hydrides partially or fully dissolved. The role played by hydrogen in solid solution and as precipitated hydrides is discussed.

  15. Deformation induced alloying in crystalline – metallic glass nano-composites

    International Nuclear Information System (INIS)

    We study the mechanisms of deformation driven chemical mixing in a metallic nanocomposite model system. More specific, we investigate shear banding at the atomic scale in an amorphous CuZr/ crystalline Cu nanolaminate, deformed by microindentation. Three CuZr/Cu multilayer systems (100 nm Cu/100 nm CuZr, 50 nm Cu/100 nm CuZr, and 10 nm Cu/100 nm CuZr) are fabricated to study the effect of layer thickness on shear band formation and deformation induced alloying. The chemical and structural evolution at different strain levels are traced by atom probe tomography and transmission electron microscopy combined with nano-beam diffraction mapping. The initially pure crystalline Cu and amorphous CuZr layers chemically mix by cross-phase shear banding after reaching a critical layer thickness. The Cu inside the shear bands develops a high dislocation density and can locally undergo transition to an amorphous state when sheared and mixed. We conclude that the severe deformation in the shear bands in the amorphous layer squeeze Zr atoms into the Cu dislocation cores in the Cu layers (thickness <5 nm), resulting in local chemical mixing

  16. Parameters of straining-induced corrosion cracking in low-alloy steels in high temperature water

    International Nuclear Information System (INIS)

    Tensile tests with slow deformation speed determine parameters of corrosion cracking at low strain rates of low-alloy steels in high-temperature water. Besides the strain rate the temperature and oxygen content of the water prove to be important for the deformation behaviour of the investigated steels 17MnMoV64, 20 MnMoNi55 and 15NiCuMoNb 5. Temperatures about 2400C, increased oxygen contents in the water and low strain rates cause a decrease of the material ductility as against the behaviour in air. Tests on the number of stress cycles until incipient cracking show that the parameters important for corrosion cracking at low strain velocities apply also to low-frequency cyclic loads with high strain amplitude. In knowledge of these influencing parameters the strain-induced corrosion cracking is counteracted by concerted measures taken in design, construction and operation of nuclear power stations. Essential aims in this matter are to avoid as far as possible inelastic strains and to fix and control suitable media conditions. (orig.)

  17. A Hydrogen-Induced Decohesion Model for Treating Cold Dwell Fatigue in Titanium-Based Alloys

    Science.gov (United States)

    Chan, Kwai S.; Moody, Jonathan

    2016-05-01

    Cold dwell fatigue in near-alpha Ti alloys is a time-dependent fracture process at ambient temperature that involves fatigue in the presence of creep to produce cracking on low-energy fracture ( e.g., cleavage) facets in hard alpha grains. In this article, cold dwell fatigue is treated as a hydrogen-induced decohesion process by using a nonlinear cohesive stress-strain relation to describe the decrease in the cohesive strength with increasing local hydrogen contents. It is postulated that during cold dwell fatigue, time-dependent deformation occurs by slip that results in dislocation pileups in soft alpha grains. The stress and dilatational fields of the dislocation pileups assist the transport of internal hydrogen atoms from soft grains to neighboring hard grains. The accumulation of internal hydrogen atoms at the trap sites leads to decohesion along crystallographic planes, which can be slip or hydride habit planes. The decohesion model is applied to treat cold dwell fatigue in Ti-6Al-4V with a basal-transverse texture by modeling the effects of hydrogen-induced decohesion on the stress-fatigue life ( S- N f) response, the time-dependent crack growth response (d a/d t), and the fracture toughness ( K c) as functions of grain orientation. A probabilistic time-dependent fatigue crack growth analysis is then performed to assess the influence of microtexture on the dwell fatigue life of a Ti-6Al-4V ring disk subjected to a long-duration hold at the peak stress of the loading cycle. The results of the probabilistic life computations indicate that dwell fatigue resistance in Ti-6Al-4V may be improved and the risk of disk fracture may be reduced significantly by controlling the microtexture or reducing the size and volume fraction of hard alpha grains in the microstructure.

  18. Nanopatterns induced by pulsed laser irradiation on the surface of an Fe-Al alloy and their magnetic properties

    International Nuclear Information System (INIS)

    We have studied nanopatterns induced by nanosecond pulsed laser irradiation on (111) plane surfaces of a polycrystalline iron-aluminum alloy and evaluated their magnetic properties. Multiple nanosecond pulsed laser irradiation induces a wavelength-dependent surface transformation of the lattice structure from a B2-type to a supersaturated body centered cubic lattice. The selective formation of surface nanopatterns consisting of holes, stripes, polygonal networks, and dot-like nanoprotrusions can be observed. Furthermore, focused magneto-optical Kerr effect measurements reveal that the magnetic properties of the resultant nanostructured region changes from a paramagnetic to a ferromagnetic phase in accordance with the number of laser pulses.

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

    NARCIS (Netherlands)

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

    2014-01-01

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

  20. Adsorbate induced surface alloy formation investigated by near ambient pressure X-ray photoelectron spectroscopy

    DEFF Research Database (Denmark)

    Nierhoff, Anders Ulrik Fregerslev; Conradsen, Christian Nagstrup; McCarthy, David Norman;

    2014-01-01

    Formation of meta-stable surface-alloys can be used as a way to tune the binding strength of reaction intermediates and could therefore be used as improved catalyst materials for heterogeneous catalysis. Understanding the role of adsorbates on such alloy surfaces can provide new insights for...

  1. Portable, real-time alloy identification of metallic wear debris from machinery lubrication systems: laser-induced breakdown spectroscopy versus x-ray fluorescence

    Science.gov (United States)

    Suresh, Pooja

    2014-05-01

    Alloy identification of oil-borne wear debris captured on chip detectors, filters and magnetic plugs allows the machinery maintainer to assess the health of the engine or gearbox and identify specific component damage. Today, such identification can be achieved in real time using portable, at-line laser-induced breakdown spectroscopy (LIBS) and Xray fluorescence (XRF) instruments. Both techniques can be utilized in various industries including aviation, marine, railways, heavy diesel and other industrial machinery with, however, some substantial differences in application and instrument performance. In this work, the performances of a LIBS and an XRF instrument are compared based on measurements of a wide range of typical aerospace alloys including steels, titanium, aluminum and nickel alloys. Measurement results were analyzed with a staged correlation technique specifically developed for the purposes of this study - identifying the particle alloy composition using a pre-recorded library of spectral signatures. The analysis is performed in two stages: first, the base element of the alloy is determined by correlation with the stored elemental spectra and then, the alloy is identified by matching the particle's spectral signature using parametric correlation against the stored spectra of all alloys that have the same base element. The correlation analysis has achieved highly repeatable discrimination between alloys of similar composition. Portable LIBS demonstrates higher detection accuracy and better identification of alloys comprising lighter elements as compared to that of the portable XRF system, and reveals a significant reduction in the analysis time over XRF.

  2. Defects induced by swift heavy ions in the 18R martensite of Cu-Zn-Al alloy

    International Nuclear Information System (INIS)

    The swift heavy ion incidence over the surface of a given material produces a strong energy deposition in a nanometric scale.Swift heavy ions, of the order of one thousand of MeV, deposit their energy as electronic excitations.This highly localized deposition can induce metastable transformations within the material. For example, in martensitic NiTi alloys irradiated with swift heavy ions, it has been observed changes on the martensitic transformation temperature and amorphous areas induced by the irradiation.In this work, the effects produced by swift heavy ions on the martensitic 18R structure of Cu-Zn-Al alloy (Cu - 12.17 Zn - 17.92 Al, in %at) were analyzed.Crystalline samples were irradiated in a direction close to the [2 1 0] of 18R with Xe+ 230 MeV, Au+ of 350 MeV and Kr+ of 200 MeV ion beams.Defects of the order of nanometers induced by the irradiation were observed by transmission electron microscopy (TEM) and high resolution electron microscopy (HREM).It was also observed, that the average size of the irradiation defects induced by Au+ ion is larger than those induced by Xe+ and Kr+ ions.In this case, no relationship between the observed defects and the energy deposition was found in the 23 keV/nn to 48 keV/nn range

  3. Lead-induced SCC of alloy 600 in plausible steam generator crevice environments

    International Nuclear Information System (INIS)

    Laboratory stress corrosion cracking (SCC) test environments developed to simulate representative BNGS-A steam generator (SG) crevice chemistries have been used to determine the susceptibility of Alloy 600 to lead-induced SCC under plausible SG conditions. Test environments were based on plant SG hideout return data and analysis of removed tubes and deposits. Deviations from the normal near neutral crevice pH environment were considered to simulate possible faulted excursion crevice chemistry and to bound the postulated crevice pH range of 3-9 (at temperature). The effect of lead contamination up to 1000 ppm, but with an emphasis on the 100 to 500 ppm range, was determined. SCC susceptibility was investigated using constant extension rate tensile (CERT) tests and encapsulated C-ring tests. CERT tests were performed at 305 degrees C on tubing representative of BNGS-A SG U-bends. The C-ring test method allowed a wider test matrix covering three temperatures (280, 304 and 315 degrees C), three strain levels (0.2%, 2% and 4%) and tubing representative of U-bends plus tubing given a simulated stress relief to represent material at the tubesheet. The results of this test program confirmed that in the absence of lead contamination, cracking does not occur in these concentrated, 3.3 to 8.9 pH range, crevice environments. Also, it appears that the concentrated crevice environments suppress lead-induced cracking relative to that seen in all-volatile-treatment (AVT) water. For the (static) C-ring tests, lead-induced SCC was only produced in the near-neutral crevice environment and was more severe at 500 ppm than 100 ppm PbO. This trend was also observed in CERT tests but some cracking/grain boundary attack occurred in acidic (pH 3.3) and alkaline (pH 8.9) environments. The C-ring tests indicated that a certain amount of resistance to cracking was imparted by simulated stress relief of the tubing. This heat treatment, confirmed to have resulted in sensitization, promoted

  4. Lead-induced stress-corrosion cracking of alloy 600 in plausible steam generator crevice environments

    International Nuclear Information System (INIS)

    Laboratory stress-corrosion cracking (SCC) test environments were developed to simulate crevice chemistries representative of Bruce Nuclear Generating Station A (BNPD A) steam generators (SGs); these test environments were used to determine the susceptibility of Alloy 600 to lead-induced SCC under plausible SG conditions. Test environments were based on plant SG hideout return data and analysis of removed tubes and deposits. Deviations from the normal near-neutral crevice pH environment were considered to simulate possible faulted excursion crevice chemistry and to bound the postulated crevice pH range of 3 to 9 (at temperature). The effect of lead contamination up to 1000 ppm, but with an emphasis on the 100- to 500-ppm range, was determined. SCC susceptibility was investigated using constant extension rate tensile (CERT) tests and encapsulated C-ring tests. CERT tests were performed at 305 degrees C on tubing representative of BNPD A SG U-bends. The C-ring test method allowed a wider test matrix, covering 3 temperatures (280 degrees C, 304 degrees C and 315 degrees C), 3 strain levels (0.2%, 2% and 4%), and tubing representative of U-bends plus tubing given a simulated stress relief to represent material at the tube sheet. The results of this test program confirmed that in the absence of lead contamination, cracking does not occur in these concentrated, 3.3 to 8.9 pH range, crevice environments. Also, it appears that the concentrated crevice environments suppress lead-induced cracking relative to that seen in all-volatile-treatment (AVT) water. For the (static) C-ring tests, lead-induced SCC was only produced in the near-neutral crevice environment and was more severe at 500 ppm than at 100 ppm PbO. This trend was also observed in CERT tests, but some cracking-grain boundary attack occurred in acidic (pH 3.3) and alkaline (pH 8.9) environments. The C-ring tests indicated that a certain amount of resistance to cracking was imparted by simulated stress relief of

  5. Nanoparticle-Induced Superior Hot Tearing Resistance of A206 Alloy

    Science.gov (United States)

    Choi, Hongseok; Cho, Woo-hyun; Konishi, Hiromi; Kou, Sindo; Li, Xiaochun

    2013-04-01

    Al- Cu alloys (such as A206) offer high strength and high fracture toughness at both room and elevated temperatures. However, their widespread applications are limited because of their high susceptibility to hot tearing. This article presents a nanotechnology approach to enhance hot-tearing resistance for A206. Specifically, γ-Al2O3 nanoparticles were used, and their effects on the hot-tearing resistance of the as-cast Al-4.5Cu alloy (A206) were investigated. While it is well known that grain refinement can improve the hot-tearing resistance of cast Al alloys, the current study demonstrated that nanoparticles can be much more effective in the case of A206. The hot-tearing susceptibilities (HTSs) of A206 alloy and its Al2O3 nanocomposite were evaluated by constrained rod casting (CRC) with a steel mold. Monolithic A206 and M206 (the Ti-free version of A206) alloys with the B contents of 20, 40, and 300 ppm from an Al-5Ti-1B master alloy addition were also cast under the same conditions for comparison. The results showed that with an addition of 1 wt pct γ-Al2O3 nanoparticles, the extent of hot tearing in A206 alloys was markedly reduced to nearly that of A356, an Al-Si alloy highly resistant to hot tearing. As compared with grain-refined A206 or M206, the hot-tearing resistance of the nanocomposites was significantly better, even though the grain size was not reduced as much. Microstructural analysis suggested that γ-Al2O3 nanoparticles modified the solidification microstructure of the eutectic of θ-Al2Cu and α-Al, as well as refined primary grains, resulting in the enhancement of the hot-tearing resistance of A206 to a level similar to that of A356 alloy.

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

    OpenAIRE

    Chyrkin, Anton

    2011-01-01

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

  7. Effect of Annealing in Magnetic Field on Ferromagnetic Nanoparticle Formation in Cu-Al-Mn Alloy with Induced Martensite Transformation.

    Science.gov (United States)

    Titenko, Anatoliy; Demchenko, Lesya

    2016-12-01

    The paper considers the influence of aging of high-temperature phase on subsequent martensitic transformation in Cu-Al-Mn alloy. The morphology of behavior of martensitic transformation as a result of alloy aging under annealing in a constant magnetic field with different sample orientation relatively to the field direction and without field was studied for direct control of the processes of martensite induction at cooling. Temperature dependences of electrical resistance, magnetic susceptibility, and magnetization, as well as field dependences of magnetization, and phase composition were found. The tendency to the oriented growth of precipitated ferromagnetic phase nanoparticles in a direction of applied field and to an increase of their volume fraction under thermal magnetic treatment of material that favors a reversibility of induced martensitic transformation is observed. PMID:27142875

  8. Stress-induced transformation in a Ni-Mn-In alloy and the concomitant change of resistivity

    Directory of Open Access Journals (Sweden)

    Kokorin V.V.

    2015-01-01

    Full Text Available In this work, the influence of mechanical stress on magnetic properties and electric resistance of a Ni-Mn-In alloy was studied. It is shown that compression of Ni-Mn-In polycrystalline specimens brings about a stressinduced martensitic transformation. Optical images recorded in-situ confirmed the formation of a martensitic structure during loading and back-transformation upon unloading. Unloading after deformation of specimens that had experienced compressive strains up to 6% resulted in full recovery of their resistivity and magnetic susceptibility. The sharp increase in the electric resistance caused by the stress-induced transformation opens up new possibilities for Ni-Mn-In alloys to be used as a material for sensors responding to mechanical stress.

  9. Proton-irradiation-induced damage in Fe–0.3 wt.%Cu alloys characterized by positron annihilation and nanoindentation

    International Nuclear Information System (INIS)

    Proton irradiation in combination with positron annihilation and nanoindentation offers the possibility to characterize irradiation damage in a range of dose. Proton irradiation experiments for Fe–0.3 wt.%Cu alloys were carried out at about 100 °C with an energy of 240 keV. Slow positron beam Doppler broadening spectroscopy was used to detect the depth dependence of microstructure evolution. The constant stiffness measurement (CSM) with a diamond Berkovich indenter was used to obtain the depth profile of hardness. The results showed that S-parameter in the analysis of positron annihilation increased with dose after irradiation owing to open-volume defects induced by proton irradiation. For specimens irradiated with different dose, hardness values exceeded that of un-irradiated alloys. The correlation between positron parameters and hardness was found. The hardness of any dpa was also calculated by Kasada method

  10. Effect of Annealing in Magnetic Field on Ferromagnetic Nanoparticle Formation in Cu-Al-Mn Alloy with Induced Martensite Transformation

    Science.gov (United States)

    Titenko, Anatoliy; Demchenko, Lesya

    2016-05-01

    The paper considers the influence of aging of high-temperature phase on subsequent martensitic transformation in Cu-Al-Mn alloy. The morphology of behavior of martensitic transformation as a result of alloy aging under annealing in a constant magnetic field with different sample orientation relatively to the field direction and without field was studied for direct control of the processes of martensite induction at cooling. Temperature dependences of electrical resistance, magnetic susceptibility, and magnetization, as well as field dependences of magnetization, and phase composition were found. The tendency to the oriented growth of precipitated ferromagnetic phase nanoparticles in a direction of applied field and to an increase of their volume fraction under thermal magnetic treatment of material that favors a reversibility of induced martensitic transformation is observed.

  11. Direct evidence for stress-induced transformation between coexisting multiple martensites in a Ni-Mn-Ga multifunctional alloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L.; Cong, D. Y.; Wang, Z. L.; Nie, Z. H.; Dong, Y. H.; Zhang, Y.; Ren, Yang; Wang, Y. D.

    2015-07-08

    The structural response of coexisting multiple martensites to stress field in a Ni-Mn-Ga multifunctional alloy was investigated by the in situ high-energy x-ray diffraction technique. Stress-induced transformation between coexisting multiple martensites was observed at 110 K, at which five-layered modulated (5M), seven-layered modulated (7M) and non-modulated (NM) martensites coexist. We found that a tiny stress of as low as 0.5 MPa could trigger the transformation from 5M and 7M martensites to NM martensite and this transformation is partly reversible. Besides the transformation between coexisting multiple martensites, rearrangement of martensite variants also occurs during loading, at least at high stress levels. The present study is instructive for designing advanced multifunctional alloys with easy actuation.

  12. Direct evidence for stress-induced transformation between coexisting multiple martensites in a Ni-Mn-Ga multifunctional alloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L.; Cong, D. Y.; Wang, Z. L.; Nie, Z. H.; Dong, Y. H.; Zhang, Y.; Ren, Yang; Wang, Y. D.

    2015-06-03

    The structural response of coexisting multiple martensites to stress field in a Ni-Mn-Ga multifunctional alloy was investigated by the in situ high-energy x-ray diffraction technique. Stress-induced transformation between coexisting multiple martensites was observed at 110 K, at which five-layered modulated (5M), seven-layered modulated (7M) and non-modulated (NM) martensites coexist. We found that a tiny stress of as low as 0.5 MPa could trigger the transformation from 5M and 7M martensites to NM martensite and this transformation is partly reversible. Besides the transformation between coexisting multiple martensites, rearrangement of martensite variants also occurs during loading, at least at high stress levels. The present study is instructive for designing advanced multifunctional alloys with easy actuation.

  13. Direct evidence for stress-induced transformation between coexisting multiple martensites in a Ni–Mn–Ga multifunctional alloy

    International Nuclear Information System (INIS)

    The structural response of coexisting multiple martensites to stress field in a Ni–Mn–Ga multifunctional alloy was investigated by the in situ high-energy x-ray diffraction technique. Stress-induced transformation between coexisting multiple martensites was observed at 110 K, at which five-layered modulated (5M), seven-layered modulated (7M) and non-modulated (NM) martensites coexist. We found that a tiny stress of as low as 0.5 MPa could trigger the transformation from 5M and 7M martensites to NM martensite and this transformation is partly reversible. Besides the transformation between coexisting multiple martensites, rearrangement of martensite variants also occurs during loading, at least at high stress levels. The present study is instructive for designing advanced multifunctional alloys with easy actuation. (paper)

  14. Use of neutron diffraction and laser-induced plasma spectroscopy in integrated authentication methodologies of copper alloy artefacts

    International Nuclear Information System (INIS)

    The present study approaches the general problem of the authentication of copper alloy artefacts of art and historical interest using non-invasive analytical techniques. It aims to demonstrate that a suitable combination of time-of-flight neutron diffraction and laser-induced plasma spectroscopy in integrated multidisciplinary authentication methodologies can provide crucial data for discriminating between genuine archaeological objects and modern counterfeits. After introducing the methodology, which is dedicated in particular to copper alloy figurines of ancient style, two representative authentication case studies are discussed. The results of the work provide evidence that the combination of multiphase analysis using TOF-N D and elemental depth profiles provided by Lips makes it possible to solve most of the present authentication problems.

  15. Ion-irradiation-induced clustering in W–Re and W–Re–Os alloys: A comparative study using atom probe tomography and nanoindentation measurements

    International Nuclear Information System (INIS)

    This study examines clustering and hardening in W–2 at.% Re and W–1 at.% Re–1 at.% Os alloys induced by 2 MeV W+ ion irradiation at 573 and 773 K. Such clusters are known precursors to the formation of embrittling precipitates, a potentially life-limiting phenomenon in the operation of fusion reactor components. Increases in hardness were studied using nanoindentation. The presence of osmium significantly increased post-irradiation hardening. Atom probe tomography analysis revealed clustering in both alloys, with the size and number densities strongly dependent on alloy composition and irradiation temperature. The highest cluster number density was found in the ternary alloy irradiated at 773 K. In the ternary alloy, Os was found to cluster preferentially compared to Re. The implications of this result for the structural integrity of fusion reactor components are discussed

  16. Fungal sterol C22-desaturase is not an antimycotic target as shown by selective inhibitors and testing on clinical isolates.

    Science.gov (United States)

    Müller, Christoph; Binder, Ulrike; Maurer, Elisabeth; Grimm, Christian; Giera, Martin; Bracher, Franz

    2015-09-01

    Inhibition of concise enzymes in ergosterol biosynthesis is one of the most prominent strategies for antifungal chemotherapy. Nevertheless, the enzymes sterol C5-desaturase and sterol C22-desaturase, which introduce double bonds into the sterol core and side chain, have not been fully investigated yet for their potential as antifungal drug targets. Lathosterol side chain amides bearing N-alkyl groups of proper length are known as potent inhibitors of the enzymes sterol C5-desaturase and sterol Δ(24)-reductase in mammalian cholesterol biosynthesis. Here we present the results of our evaluation of these amides for their ability to inhibit enzymes in fungal ergosterol biosynthesis. In the presence of inhibitor(s) an accumulation of sterols lacking a double bond at C22/23 (mainly ergosta-5,7-dien-3β-ol) was observed in Candida glabrata, Saccharomyces cerevisiae, and Yarrowia lipolytica. Hence, the lathosterol side chain amides were identified as selective inhibitors of the fungal sterol C22-desaturase, which was discussed as a specific target for novel antifungals. One representative inhibitor, (3S,20S)-20-N-butylcarbamoylpregn-7-en-3β-ol was subjected to antifungal susceptibility testing on patient isolates according to modified EUCAST guidelines. But, the test organisms showed no significant reduction of cell growth and/or viability up to an inhibitor concentration of 100μg/mL. This leads to the conclusion that sterol C22-desaturase is not an attractive target for the development of antifungals. PMID:26022150

  17. Irradiation induced surface segregation in concentrated alloys: a contribution; Contribution a l`etude de la segregation de surface induite par irradiation dans les alliages concentres

    Energy Technology Data Exchange (ETDEWEB)

    Grandjean, Y.

    1996-12-31

    A new computer modelization of irradiation induced surface segregation is presented together with some experimental determinations in binary and ternary alloys. The model we propose handles the alloy thermodynamics and kinetics at the same level of sophistication. Diffusion is described at the atomistic level and proceeds vis the jumps of point defects (vacancies, dumb-bell interstitials): the various jump frequencies depend on the local composition in a manner consistent with the thermodynamics of the alloy. For application to specific alloys, we have chosen the simplest statistical approximation: pair interactions in the Bragg Williams approximation. For a system which exhibits the thermodynamics and kinetics features of Ni-Cu alloys, the model generates the behaviour parameters (flux and temperature) and of alloy composition. Quantitative agreement with the published experimental results (two compositions, three temperatures) is obtained with a single set of parameters. Modelling austenitic steels used in nuclear industry requires taking into account the contribution of dumbbells to mass transport. The effects of this latter contribution are studied on a model of Ni-Fe. Interstitial trapping on dilute impurities is shown to delay or even suppress the irradiation induced segregation. Such an effect is indeed observed in the experiments we report on Fe{sub 50}Ni{sub 50} and Fe{sub 49}Ni{sub 50}Hf{sub 1} alloys. (author). 190 refs.

  18. Thermal stability of the induced magnetic anisotropy and structure of the nanocrystalline alloy FeCuNbSiB

    International Nuclear Information System (INIS)

    The magnetic anisotropy induced in the ribbons of the Fe73.5Cu1Nb3Si13.5B9 alloy in the course of stress annealing combined with the nanocrystallising one was investigated. Crystalline phases formed during the above treatments were studied by the Moessbauer method. Analysis of the Moessbauer results showed that the content of the Fe-Si phases depends neither on the exposure time nor on the value of the induced magnetic anisotropy constant. At the same time, in the regions containing, along with Fe, Nb and B the process of redistributing the elements proceeds with time, and the deeper the process, the higher the thermal stability of the induced magnetic anisotropy

  19. The Kinetics of Dislocation Loop Formation in Ferritic Alloys Through the Aggregation of Irradiation Induced Defects

    Science.gov (United States)

    Kohnert, Aaron Anthony

    The mechanical properties of materials are often degraded over time by exposure to irradiation environments, a phenomenon that has hindered the development of multiple nuclear reactor design concepts. Such property changes are the result of microstructural changes induced by the collision of high energy particles with the atoms in a material. The lattice defects generated in these recoil events migrate and interact to form extended damage structures. This study has used theoretical models based on the mean field chemical reaction rate theory to analyze the aggregation of isolated lattice defects into larger microstructural features that are responsible for long term property changes, focusing on the development of black dot damage in ferritic iron based alloys. The purpose of such endeavors is two-fold. Primarily, such models explain and quantify the processes through which these microstructures form. Additionally, models provide insight into the behavior and properties of the point defects and defect clusters which drive general microstructural evolution processes. The modeling effort presented in this work has focused on physical fidelity, drawing from a variety of sources of information to characterize the unobservable defect generation and agglomeration processes that give rise to the observable features reported in experimental data. As such, the models are based not solely on isolated point defect creation, as is the case with many older rate theory approaches, but instead on realistic estimates of the defect cluster population produced in high energy cascade damage events. Experimental assessments of the microstructural changes evident in transmission electron microscopy studies provide a means to measure the efficacy of the kinetic models. Using common assumptions of the mobility of defect clusters generated in cascade damage conditions, an unphysically high density of damage features develops at the temperatures of interest with a temperature dependence

  20. Effect of natural aging on quench-induced inhomogeneity of microstructure and hardness in high strength 7055 aluminum alloy

    International Nuclear Information System (INIS)

    Highlights: • The quench-induced hardness inhomogeneity in 7055 Al alloy decreases by natural aging. • The reason is discussed based on natural aging effect on microstructural inhomogeneity. • Natural aging decreases the difference of hardening precipitates due to slow quenching. • GPII zones appear in the rapidly-quenched sample after natural aging for 17,280 h. - Abstract: The effect of natural aging on quench-induced inhomogeneity of microstructure and hardness in high strength 7055 aluminum alloy was investigated by means of end quenching technique, transmission electron microscopy and differential scanning calorimetry thermal analysis. The hardness inhomogeneity in the end-quenched specimens after artificial aging decreases with the increase of natural aging time prior to artificial aging. The quench-induced differences in the amount and size of η′ phase are large in the end-quenched specimen after artificial aging at 120 °C for 24 h, leading to high hardness inhomogeneity. Natural aging for a long time results in a larger amount of stable GPI zones in the slowly-quenched sample, and thus decreases such differences in the end-quenched specimens after subsequent artificial aging, leading to lower hardness inhomogeneity. The hardness inhomogeneity can be reduced from 14% to be 4% by natural aging for 17,280 h prior to artificial aging

  1. Kinetics of radiation-induced segregation in electron-irradiated dilute NiSi and NiGe alloys

    International Nuclear Information System (INIS)

    The efficiency and the kinetics of the radiation-induced segregation during 3 MeV electron irradiation has been investigated in dilute NiSi and NiGe alloys in the temperature range from 535 K to 735 K. The analysis of the Si and the Ge concentration in solid solution in Ni was performed by damage rate measurements at 86 K in the case of NiSi and 73 K in the case of NiGe. The results indicate a high efficiency of the radiation-induced Si segregation. Between two and ten Frenkel defects must be produced to transport one Si atom to the sinks, whereas radiation-induced segregation could not be detected in NiGe alloys by this method. The kinetics of the mass transport can be described consistently by the assumption of mobile but thermally unstable Si interstitial complexes. From the evaluation of the experimental data we obtain a value of 0.23 eV for the binding energy of the Si interstitial complex. (orig.)

  2. Kinetics of radiation-induced segregation in electron-irradiated dilute NiSi and NiGe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, A.; Weigert, M.; Dworschak, F.

    1988-05-01

    The efficiency and the kinetics of the radiation-induced segregation during 3 MeV electron irradiation has been investigated in dilute NiSi and NiGe alloys in the temperature range from 535 K to 735 K. The analysis of the Si and the Ge concentration in solid solution in Ni was performed by damage rate measurements at 86 K in the case of NiSi and 73 K in the case of NiGe. The results indicate a high efficiency of the radiation-induced Si segregation. Between two and ten Frenkel defects must be produced to transport one Si atom to the sinks, whereas radiation-induced segregation could not be detected in NiGe alloys by this method. The kinetics of the mass transport can be described consistently by the assumption of mobile but thermally unstable Si interstitial complexes. From the evaluation of the experimental data we obtain a value of 0.23 eV for the binding energy of the Si interstitial complex.

  3. Stress-induced thickening of Ω phase in Al–Cu–Mg alloys containing various Ag additions

    International Nuclear Information System (INIS)

    The thickening of Ω phase in Al–Cu–Mg alloys containing various bulk Ag contents during stress aging at 200 °C with a tensile stress of 240 MPa was investigated by a combination of transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and atom probe tomography (APT). TEM characterization confirmed preferred orientation of Ω phase in all stress-aged samples. Corresponding quantitative TEM calculations revealed the thickening kinetics of Ω phase was significantly accelerated during stress aging as compared to that during stress-free aging at 200 °C. HRTEM analysis on the α/Ω interfacial structure confirmed that the applied tensile stress facilitated the rapid nucleation of the growth ledge on the broad face of Ω phase, thereby resulting in the accelerated plate thickening during stress aging at 200 °C. Meanwhile, quantitative TEM analysis highlighted the stress-induced thickening of Ω phase at 200 °C was affected by the bulk Ag content. This was consistent with the HRTEM observation as the ledge nucleation was found to be suppressed with increasing Ag addition. Our APT analysis on different stress-aged samples further suggested the progressive enrichment of Ag atoms in the segregation layer helped to stabilize the interfacial structure and was responsible for the lowest nucleation rate of the ledge in 1.77Ag alloy as compared to that in 0.46Ag alloy

  4. Modelling current-induced magnetization switching in Heusler alloy Co2FeAl-based spin-valve nanopillar

    Science.gov (United States)

    Huang, H. B.; Ma, X. Q.; Liu, Z. H.; Zhao, C. P.; Chen, L. Q.

    2014-04-01

    We investigated the current-induced magnetization switching in a Heusler alloy Co2FeAl-based spin-valve nanopillar by using micromagnetic simulations. We demonstrated that the elimination of the intermediate state is originally resulted from the decease of effective magnetic anisotropy constant. The magnetization switching can be achieved at a small current density of 1.0 × 104 A/cm2 by increasing the demagnetization factors of x and y axes. Based on our simulation, we found magnetic anisotropy and demagnetization energies have different contributions to the magnetization switching.

  5. Stress-induced large Curie temperature enhancement in Fe(sub 64)Ni(sub 36) Invar alloy.

    Energy Technology Data Exchange (ETDEWEB)

    Gorria, P.; Martinez-Blanco, D.; Perez, M. J.; Blanco, J. A.; Hernando, A.; Laguna-Marco, M. A.; Haskel, D.; Souza-Neto, N. M.; Xmith, R. I.; Marshall, W. G.; Garbarino, G.; Mezouar, M.; Fernandez-Martinez, A.; Chaboy, J.; Fernandez Barquin, L.; Rodriguez Castrillon, J. A.; Moldovan, M.; Garcia Alonso, J. I.; Zhang, J.; Llobet, A.; Jiang, J. S.; Univ. de Oviedo; Inst. de Magnetismo Aplicado; ISIS Facility; ESRF; Univ.Grenoble and CNRS; CSIC-Univ. de Zaragoza; Univ. de Cantabria; LANL

    2009-01-01

    We have succeeded in increasing up to 150 K the Curie temperature in the Fe{sub 64}N{sub 36}6 invar alloy by means of a severe mechanical treatment followed by a heating up to 1073 K. The invar behavior is still present as revealed by the combination of magnetic measurements with neutron and x-ray techniques under extreme conditions, such as high temperature and high pressure. The proposed explanation is based in a selective induced microstrain around the Fe atoms, which causes a slight increase in the Fe-Fe interatomic distances, thus reinforcing ferromagnetic interactions due to the strong magnetoelastic coupling in these invar compounds.

  6. Measurement and analysis of radioactivity induced in steels and a vanadium alloy by 14-MeV neutrons

    Science.gov (United States)

    Richter, D.; Forrest, R. A.; Freiesleben, H.; Kovalchuk, Va. D.; Kovalchuk D, Vi.; Markovskij, D. V.; Seidel, K.; Tereshkin, V. I.; Unholzer, S.

    2000-12-01

    Samples of the structural material of the International Thermonuclear Experimental Reactor (SS316), of the low-activation steels MANET and F82H, and of the vanadium alloy V4Ti4Cr were irradiated with D-T fusion neutrons. The radioactivities induced were determined after irradiation several times during decay by γ-spectroscopy. The results were analysed with the European Activation System (EASY-97). In order to validate EASY-97, the total activities of the samples are compared, and ratios of calculated-to-experimental values for the individual activities are derived and discussed.

  7. Modelling current-induced magnetization switching in Heusler alloy Co2FeAl-based spin-valve nanopillar

    International Nuclear Information System (INIS)

    We investigated the current-induced magnetization switching in a Heusler alloy Co2FeAl-based spin-valve nanopillar by using micromagnetic simulations. We demonstrated that the elimination of the intermediate state is originally resulted from the decease of effective magnetic anisotropy constant. The magnetization switching can be achieved at a small current density of 1.0 × 104 A/cm2 by increasing the demagnetization factors of x and y axes. Based on our simulation, we found magnetic anisotropy and demagnetization energies have different contributions to the magnetization switching

  8. Experimental and Theoretical Investigation of Three Alloy 690 Mockup Components: Base Metal and Welding Induced Changes

    Directory of Open Access Journals (Sweden)

    Rickard R. Shen

    2014-01-01

    Full Text Available The stress corrosion cracking (SCC resistance of cold deformed thermally treated (TT Alloy 690 has been questioned in recent years. As a step towards understanding its relevancy for weld deformed Alloy 690 in operating plants, Alloy 690 base metal and heat affected zone (HAZ microstructures of three mockup components have been studied. All mockups were manufactured using commercial heats and welding procedures in order to attain results relevant to the materials in the field. Thermodynamic calculations were performed to add confidence in phase identification as well as understanding of the evolution of the microstructure with temperature. Ti(C,N banding was found in all materials. Bands with few large Ti(C,N precipitates had negligible effect on the microstructure, whereas bands consisting of numerous small precipitates were associated with locally finer grains and coarser M23C6 grain boundary carbides. The Ti(C,N remained unaffected in the HAZ while the M23C6 carbides were fully dissolved close to the fusion line. Cold deformed solution annealed Alloy 690 is believed to be a better representation of this region than cold deformed TT Alloy 690.

  9. Study by electrical resistivity measurements of the radiation induced defects in gold-copper alloys

    International Nuclear Information System (INIS)

    Point defect production rate in Cu3Au and CuAu ordered and disordered alloys was studied by electrical resistivity measurements, as function of electron energy ranging from 0.4 to 2.5 MeV. The irradiations were performed at 20 K. The production curves are analysed using a displacement model for diatomic materials and the following values are found for the average displacement threshold energies: Esub(d)sup(Cu) approximately 22 eV and Esub(d)sup(Au) approximately 18 eV, for both alloys. Elementary defect migration was examined during isochronal annealing performed after irradiations. A simple type of self-interstitial seems to migrate in the ordered alloys: probably a split-interstitial of Cu-Cu type. Interstitial migration seems to be very difficult and complex in the disordered alloys. Vacancy mobility was detected after recovery at temperature above 300 K and was responsible of an increase of long range order. Fast neutron irradiations at 20 K produce disordering in the initially ordered alloys. Ratios of 38 and 18 antistructure defects per atomic displacement are estimated for Cu3Au and CuAu respectively

  10. Hydrogen-induced superabundant vacancies in electrodeposited Fe–C alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Fukumuro, Naoki; Kojima, Saeka; Fujino, Moeko; Mizuta, Yasunori; Maruo, Toshiaki; Yae, Shinji [Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, Himeji, Hyogo (Japan); Fukai, Yuh [Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo (Japan)

    2015-10-05

    Highlights: • The hydrogen behavior in electrodeposited Fe–C films was investigated. • The H content in Fe–C films increased with increasing of C content. • The changes in lattice parameters of Fe–C films were observed. • Both the contraction and expansion of lattice were reduced by heat treatments. • The limiting composition of VacCH{sub 5} clusters was estimated from the results. - Abstract: Fe–C alloy films containing supersaturated C and H were prepared by electrodeposition, and investigated for the hydrogen behavior in annealing processes utilizing X-ray diffraction and thermal desorption spectroscopy. The H content x{sub H} (x{sub H} = H/Fe) in the films increased from about 0.031 in pure Fe to about 0.36 in Fe–C alloy (x{sub C} = C/Fe = 0.073) in proportion to the C content. The lattice contraction of about 0.2% was observed in pure Fe films, whereas the lattice expansion increasing with C content was observed in Fe–C alloy films. Both the lattice contraction of the Fe films and the lattice expansion of the Fe–C alloy films were decreased as H was desorbed during heat treatments. The atomistic structure of vacancy–hydrogen and vacancy–carbon–hydrogen clusters in Fe–C alloy films is discussed, based on these experimental results.

  11. Investigation of early stage deformation mechanisms in a metastable β titanium alloy showing combined twinning-induced plasticity and transformation-induced plasticity effects

    International Nuclear Information System (INIS)

    As expected from the alloy design procedure, combined twinning-induced plasticity and transformation-induced plasticity effects are activated in a metastable β Ti–12 wt.% Mo alloy. In situ synchrotron X-ray diffraction, electron backscatter diffraction and transmission electron microscopy observations were carried out to investigate the deformation mechanisms and microstructure evolution sequence. In the early deformation stage, primary strain/stress-induced phase transformations (β → ω and β → α″) and primary mechanical twinning ({3 3 2}〈1 1 3〉 and {1 1 2}〈1 1 1〉) are activated simultaneously. Secondary martensitic phase transformation and secondary mechanical twinning are then triggered in the twinned β zones. The {3 3 2}〈1 1 3〉 twinning and the subsequent secondary mechanisms dominate the early-stage deformation process. The evolution of the deformation microstructure results in a high strain-hardening rate (∼2 GPa), bringing about high tensile strength (∼1 GPa) and large uniform elongation (>0.38)

  12. In Situ Nanocrystallization-Induced Hardening of Amorphous Alloy Matrix Composites Consolidated by Spark Plasma Sintering

    Science.gov (United States)

    Singh, Ashish; Paul, Tanaji; Katakam, Shravana; Dahotre, Narendra B.; Harimkar, Sandip P.

    2016-07-01

    In situ nanocrystallization of amorphous alloys has recently emerged as a suitable technique for forming nanocomposites with improved mechanical properties. In this paper, we report on the spark plasma sintering (SPS) of Fe-based amorphous alloys with in situ-formed nanocrystals of (Fe,Cr)23(C,B)6. The SPS was performed with a range of sintering temperatures (570-800°C) in and above the supercooled liquid region of the alloy. Significant enhancement in relative density was observed with increasing sintering temperature due to particle deformation and improved interparticle contacts. The formation of nanocrystalline particles and enhanced densification resulted in an increase in the hardness of the nanocomposites from about 1150-1375 VHN.

  13. The effect of trapping on hydrogen-induced plasticity and fracture in structural alloys

    International Nuclear Information System (INIS)

    It has previously been noted that, for a given alloy system, microstructural manipulation may result in large variations in hydrogen susceptibility at a given strength level; it may even be possible to obtain inversions of susceptibility in which higher strengths may be associated with greater embrittlement resistance. An examination is presently conducted of the consequences of hydrogen-heterogeneity interactions, or 'trapping', in several alloy systems; these will include both conventional ferrous and nonferrous ones, and novel alloy systems. Deleterious trapping dominates behavior in the presence of large local concentrations of hydrogen; plasticity modifications due to hydrogen exercise a dominant influence on embrittlement susceptibility when relatively weak traps are present, as well as when a more uniform distribution of hydrogen is present. 26 refs

  14. The effect of trapping on hydrogen-induced plasticity and fracture in structural alloys

    Science.gov (United States)

    Bernstein, I. M.; Dollar, M.

    1990-01-01

    It has previously been noted that, for a given alloy system, microstructural manipulation may result in large variations in hydrogen susceptibility at a given strength level; it may even be possible to obtain inversions of susceptibility in which higher strengths may be associated with greater embrittlement resistance. An examination is presently conducted of the consequences of hydrogen-heterogeneity interactions, or 'trapping', in several alloy systems; these will include both conventional ferrous and nonferrous ones, and novel alloy systems. Deleterious trapping dominates behavior in the presence of large local concentrations of hydrogen; plasticity modifications due to hydrogen exercise a dominant influence on embrittlement susceptibility when relatively weak traps are present, as well as when a more uniform distribution of hydrogen is present.

  15. Powder metallurgy and mechanical alloying effects on the formation of thermally induced martensite in an FeMnSiCrNi SMA

    Directory of Open Access Journals (Sweden)

    Pricop Bogdan

    2015-01-01

    Full Text Available By ingot metallurgy (IM, melting, alloying and casting, powder metallurgy (PM, using as-blended elemental powders and mechanical alloying (MA of 50 % of particle volume, three types of FeMnSiCrNi shape memory alloy (SMA specimens were fabricated, respectively. After specimen thickness reduction by hot rolling, solution treatments were applied, at 973 and 1273 K, to thermally induce martensite. The resulting specimens were analysed by X-ray diffraction (XRD and scanning electron microscopy (SEM, in order to reveal the presence of ε (hexagonal close-packed, hcp and α’ (body centred cubic, bcc thermally induced martensites. The reversion of thermally induced martensites, to γ (face centred cubic, fcc austenite, during heating, was confirmed by dynamic mechanical analysis (DMA, which emphasized marked increases of storage modulus and obvious internal friction maxima on DMA thermograms. The results proved that the increase of porosity degree, after PM processing, increased internal friction, while MA enhanced crystallinity degree.

  16. Field Induced Magnetic Moments in a Metastable Iron-Mercury Alloy

    DEFF Research Database (Denmark)

    Pedersen, M.S.; Mørup, Steen; Linderoth, Søren;

    1996-01-01

    The magnetic properties of a metastable iron-mercury alloy have been investigated in the temperature range from 5 to 200 K by Mossbauer spectroscopy and magnetization measurements. At low temperature the magnetic moment per iron atom is larger than af alpha-Fe. The effective spontaneous magnetic...... moment for the iron-mercury alloy extrapolated to 0 K was found to be 2.40 Bohr magnetons per iron atom. By applying magnetic fields up to 12 T it was possible to further increase the magnetization. Mossbauer results showed that the high field susceptibility could not be explained by spin canting effects...

  17. Inhibition of the Sulfide Induced Pitting of Copper Nickel Alloy using Benzotriazole

    OpenAIRE

    Nageh K. Allam, Hussein S. Hegazy and Elsayed A. Ashour

    2007-01-01

    Benzotriazole (BTAH) affects the localized corrosion of Cu10Ni alloy in 3.4% NaCl salt water containing 2 ppm sulfide ions. BTAH concentrations > 5 x 10-4 M imparted corrosion inhibiting efficiency that increased with its concentration. On the other hand, a concentration of 10-4 M BTAH acted as a promoter of pitting corrosion of the alloy in the above medium. The results of optical and scanning electron microscopy could be rationalized on the basis of competitive adsorption of BTAH and sulfid...

  18. Grain boundary migration induced segregation in V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Ohnuki, S.; Takahashi, H. [Univ. of Hokkaido (Japan)

    1996-10-01

    Analytical electron microscopy results are reported for a series of vanadium alloys irradiated in the HFIR JP23 experiment at 500{degrees}C. Alloys were V-5Cr-5Ti and pure vanadium which are expected to have transmuted to V-15Cr-5Ti and V-10Cr following irradiation. Analytical microscopy confirmed the expected transmutation occurred and showed redistribution of Cr and Ti resulting from grain boundary migration in V-5Cr-5Ti, but in pure V, segregation was reduced and no clear trends as a function of position near a boundary were identified.

  19. High-pressure torsion induced microstructural evolution in a hexagonal close-packed Zr alloy

    International Nuclear Information System (INIS)

    Transmission electron microscopy was used to investigate the microstructural evolution of a hexagonal close-packed Zr alloy subjected to high-pressure torsion at 3.8 GPa. Results show that an inhomogeneous grain size distribution was obtained at the early stages of deformation, which is unique to hexagonal structures. {1-bar 011} deformation twins, which have never been reported in Zr alloys, were observed in coarse grains but not in refined grains. The grain refinement mechanism is discussed based on the experimental observation.

  20. Darkening effect on AZ31B magnesium alloy surface induced by nanosecond pulse Nd:YAG laser

    International Nuclear Information System (INIS)

    Permanent darkening effect was achieved on surface of AZ31B Mg alloy irradiated with nanosecond pulse Nd:YAG laser, and special attention was made to examine how surface structure as well as oxidation affect the darkening effect. Experiments were carried out to characterize morphological evolution and chemical composition of the irradiated areas by optical reflection spectrometer, Talysurf surface profiler, SEM, EDS, and XPS. The darkening effect was found to be occurred at the surface under high laser energy. Optical spectra showed that the induced darkening surface was uniform over the spectral range from 200 nm to 1100 nm. SEM and surface profiler showed that surface morphology of darkening areas consisted of large number of micron scale cauliflower-like clusters and protruding particles. EDS and XPS showed that compared to non-irradiated area, oxygen content at the darkening areas increased significantly. It was proposed a mechanism that involved trapping of light in the surface morphology and chemistry variation of irradiated areas to explain the laser-induced darkening effect on AZ31B Mg alloy.

  1. Influence of the microstructural changes and induced residual stresses on tensile properties of wrought magnesium alloy friction stir welds

    International Nuclear Information System (INIS)

    Highlights: ► Study of AZ31 FSW mechanical behaviour. ► Early yielding occurs in the TMAZ, the nugget and base metal zones undergo almost no plastic strains. ► Texture gradient in the TMAZ localises the deformations in this area. ► Residual stresses have a major influence in FSW mechanical behaviour. - Abstract: Friction stir welding induces a microstructural evolution and residual stresses that will influence the resulting mechanical properties. Friction stir welds produced from magnesium alloy hot rolled plates were studied. Electron back scattered diffraction was used to determine the texture evolution, residual stresses were analysed using X ray diffraction and tensile tests coupled with speckle interferometry were performed. The residual stresses induced during friction stir welding present a major influence on the final mechanical properties.

  2. Positive effect of hydrogen-induced vacancies on mechanical alloying of Fe and Al

    Czech Academy of Sciences Publication Activity Database

    Čížek, J.; Lukáč, F.; Procházka, I.; Vlček, M.; Jirásková, Yvonna; Švec, P.; Janičkovič, D.

    2015-01-01

    Roč. 629, APR (2015), s. 22-26. ISSN 0925-8388 R&D Projects: GA ČR(CZ) GAP108/11/1350 Institutional support: RVO:68081723 Keywords : Nanostructured materials * Mechanical alloying * Vacancy formation * Positron spectroscopies * Mössbauer spectroscopy * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.999, year: 2014

  3. Effect of Residual Strain Induced by Cold Working on PWSCC of Alloy 690

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Woo; Hwang, Seong Sik; Lim, Yun Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    PWSCC has been widely reported to occur in the inside of the steam generator (SG) tubing, and in other instrumentation nozzles such as the control rod drive mechanism (CRDM) penetrations, especially on those surfaces having a dissimilar metal welds (DMW) or those heavily machined. Under an abnormal working procedure or without a sufficient post-heat treatment for stress relaxation, a high tensile stress can persist after welding or cold working of the alloys. Variation of a strain field is also accompanied by the cold working or machining process. The conventional method for measuring the residual strain is a micro-hardness test, which has a limitation owing to the presence of precipitates and grain boundaries in the matrix of the test specimen. A new technique of electron backscatter diffraction (EBSD) has recently been applied to residual strain analysis on a micro-scale to overcome this limitation. This work is concerning a quantitative analysis of the local residual strain by EBSD and its effect on the PWSCC of Alloy 690 CRDM materials. In this work, the local residual strain of Alloy 690 CRDM materials cold-worked at various plastic strain levels was quantitatively evaluated using an EBSD analysis. From KAM maps, it was confirmed that the residual strain increased with cold-working, and a higher strain was concentrated at the grain boundary than in the matrix. The severe strain field localized at the grain boundary accelerated the inter-grannular growth of PWSCC of Alloy 690.

  4. Effect of Residual Strain Induced by Cold Working on PWSCC of Alloy 690

    International Nuclear Information System (INIS)

    PWSCC has been widely reported to occur in the inside of the steam generator (SG) tubing, and in other instrumentation nozzles such as the control rod drive mechanism (CRDM) penetrations, especially on those surfaces having a dissimilar metal welds (DMW) or those heavily machined. Under an abnormal working procedure or without a sufficient post-heat treatment for stress relaxation, a high tensile stress can persist after welding or cold working of the alloys. Variation of a strain field is also accompanied by the cold working or machining process. The conventional method for measuring the residual strain is a micro-hardness test, which has a limitation owing to the presence of precipitates and grain boundaries in the matrix of the test specimen. A new technique of electron backscatter diffraction (EBSD) has recently been applied to residual strain analysis on a micro-scale to overcome this limitation. This work is concerning a quantitative analysis of the local residual strain by EBSD and its effect on the PWSCC of Alloy 690 CRDM materials. In this work, the local residual strain of Alloy 690 CRDM materials cold-worked at various plastic strain levels was quantitatively evaluated using an EBSD analysis. From KAM maps, it was confirmed that the residual strain increased with cold-working, and a higher strain was concentrated at the grain boundary than in the matrix. The severe strain field localized at the grain boundary accelerated the inter-grannular growth of PWSCC of Alloy 690

  5. ARXPS and DFT studies of thermally induced Pb surface segregation on Au/Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Völker, Edgar [Chemistry Department, University of Liverpool, Liverpool L69 7ZD (United Kingdom); Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE-CONICET, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EHA (Argentina); Williams, Federico J., E-mail: fwilliams@qi.fcen.uba.ar [Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE-CONICET, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EHA (Argentina); Jacob, Timo [Institute of Electrochemistry, Ulm University, Albert-Einstein-Allee 47, D-89081 Ulm (Germany); Schiffrin, David J. [Chemistry Department, University of Liverpool, Liverpool L69 7ZD (United Kingdom)

    2014-02-15

    Highlights: • Surface segregation of Pb impurities in AuCu alloys was studied by ARXPS and DFT. • ARXPS show a 23% surface coverage by Pb atoms. • DFT calculations predict a ¼ ML coverage of Pb atoms in the first atomic layer. • The results show that bulk systems are affected while leaving nanoparticulate systems unaffected. -- Abstract: Surface segregation of Pb has been studied using angle resolved X-ray Photoelectron Spectroscopy (ARXPS) and Density Functional Theory (DFT) modelling in a polycrystalline Au{sub 0.85}Cu{sub 0.15} alloy. Au surface enrichment was found in the alloy surface, whereas Pb surface enrichment was detected after annealing. ARXPS depth profiles show a 23% surface coverage by Pb atoms. DFT calculations predict an approximate coverage of ¼ monolayer (ML) of Pb atoms in the first atomic layer, consistent with the experimental results. The results presented here are an example of the importance of low concentration of impurities in determining the surface composition of bulk alloys.

  6. Antisite-defect-induced surface segregation in ordered NiPt alloy

    DEFF Research Database (Denmark)

    Pourovskii, L.V.; Ruban, Andrei; Abrikosov, I.A.;

    2003-01-01

    By means of first principles simulations we demonstrate that tiny deviations from stoichiometry in the bulk composition of the NiPt-L1(0) ordered alloy have a great impact on the atomic configuration of the (111) surface. We predict that at T=600 K the (111) surface of the Ni51Pt49 and Ni50Pt50 a...

  7. ARXPS and DFT studies of thermally induced Pb surface segregation on Au/Cu alloys

    International Nuclear Information System (INIS)

    Highlights: • Surface segregation of Pb impurities in AuCu alloys was studied by ARXPS and DFT. • ARXPS show a 23% surface coverage by Pb atoms. • DFT calculations predict a ¼ ML coverage of Pb atoms in the first atomic layer. • The results show that bulk systems are affected while leaving nanoparticulate systems unaffected. -- Abstract: Surface segregation of Pb has been studied using angle resolved X-ray Photoelectron Spectroscopy (ARXPS) and Density Functional Theory (DFT) modelling in a polycrystalline Au0.85Cu0.15 alloy. Au surface enrichment was found in the alloy surface, whereas Pb surface enrichment was detected after annealing. ARXPS depth profiles show a 23% surface coverage by Pb atoms. DFT calculations predict an approximate coverage of ¼ monolayer (ML) of Pb atoms in the first atomic layer, consistent with the experimental results. The results presented here are an example of the importance of low concentration of impurities in determining the surface composition of bulk alloys

  8. 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.

  9. Neutron-radiation induced changes in electrical resistivity of copper alloys for MFE applications

    International Nuclear Information System (INIS)

    The objective of this work was to identify, by fast-neutron irradiation and post-irradiation testing, one or more mechanically acceptable copper alloys with low yet stable dc electrical resistivity values (rho/sub e/) and thus with attractive thermal conductivity (K) performance for first-wall applications. Values of rho/sub e/ were measured for two elemental (high-purity) coppers and four commercial copper alloys subjected in EBR-II to neutron fluences of 0.4 and 2.0 x 1026 n/m2 at 658K. Relative to annealed controls, two alumina-dispersed alloys gave the best results: increases in rho/sub e/ (and 1/K) of 6-7% at the high fluence, with no significant changes (per paper 8.1 preceding) in the corresponding yield stresses. Changes in rho/sub e/ for MZC and AMZIRC Cu alloys were smaller than this, but the corresponding yield stresses were strongly diminished at the high fluence. Void swelling and accumulation and transmuted Ni and Zn contributed significantly to the observed changes in rho/sub e/

  10. Thermally induced crystallization of amorphous Fe40Ni40P14B6 alloy

    Czech Academy of Sciences Publication Activity Database

    Vasić, M.; Blagojević, V. A.; Begović, N. N.; Žák, Tomáš; Pavlović, V. B.; Minić, Dragica M.

    2015-01-01

    Roč. 614, AUG (2015), s. 129-136. ISSN 0040-6031 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Amorphous alloy * Crystallization * Kinetics * Deconvolution * Impingement * Surface morphology Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.184, year: 2014

  11. Hydrogen embrittlement and hydrogen induced stress corrosion cracking of high alloyed austenitic materials; Wasserstoffversproedung und wasserstoffinduzierte Spannungsrisskorrosion hochlegierter austenitischer Werkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Mummert, K.; Uhlemann, M.; Engelmann, H.J. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany)

    1998-11-01

    The susceptiblity of high alloyed austenitic steels and nickel base alloys to hydrogen-induced cracking is particularly determined by 1. the distribution of hydrogen in the material, and 2. the microstructural deformation behaviour, which last process is determined by the effects of hydrogen with respect to the formation of dislocations and the stacking fault energy. The hydrogen has an influence on the process of slip localization in slip bands, which in turn affects the microstructural deformation behaviour. Slip localization increases with growing Ni contents of the alloys and clearly reduces the ductility of the Ni-base alloy. Although there is a local hydrogen source involved in stress corrosion cracking, emanating from the corrosion process at the cathode, crack growth is observed only in those cases when the hydrogen concentration in a small zone ahead of the crack tip reaches a critical value with respect to the stress conditions. Probability of onset of this process gets lower with growing Ni content of the alloy, due to increasing diffusion velocity of the hydrogen in the austenitic lattice. This is why particularly austenitic steels with low Ni contents are susceptible to transcrystalline stress corrosion cracking. In this case, the microstructural deformation process at the crack tip is also influenced by analogous processes, as could be observed in hydrogen-loaded specimens. (orig./CB) [Deutsch] Die Empfindlichkeit von hochlegierten austentischen Staehlen und Nickelbasislegierungen gegen wasserstoffinduziertes Risswachstum wird im wesentlichen bestimmt durch 1. die Verteilung von Wasserstoff im Werkstoff und 2. das mikrostrukturelle Verformungsverhalten. Das mikrostrukturelle Deformationsverhalten ist wiederum durch den Einfluss von Wasserstoff auf die Versetzungsbildung und die Stapelfehlerenergie charakterisiert. Das mikrostrukturelle Verformungsverhalten wird durch wasserstoffbeeinflusste Gleitlokalisierung in Gleitbaendern bestimmt. Diese nimmt mit

  12. The magnitude of heat treatment induced residual stresses and the thermal stress relief of aluminium alloys

    OpenAIRE

    Robinson, J S; Tanner, D.A

    2002-01-01

    To produce useful strengthening, precipitation hardenable aluminium alloys rely on rapid quenching from the solution heat treatment temperature to suppress the formation of coarse equilibrium second phases. An unavoidable consequence of the rapid quenching of thick sections is the severe thermal gradients that quickly develop in the material. The attendant inhomogeneous plastic flow can then result in the establishment of residual stresses. Established procedures exist to minim...

  13. Structural transformations of Fe81B13Si4C2 amorphous alloy induced by heating

    Czech Academy of Sciences Publication Activity Database

    Minić, Dragica M.; Minić, Dušan M.; Žák, Tomáš; Roupcová, Pavla; David, Bohumil

    2011-01-01

    Roč. 323, č. 5 (2011), s. 400-404. ISSN 0304-8853 R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : Amorphous material * Metallic glass * Metal and alloy * Phase transition * Thermal analysis * Mössbauer spectrum * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.780, year: 2011

  14. Tailoring the mechanical properties of titanium alloys via plasticity induced transformations

    OpenAIRE

    Neelakantan, S.

    2010-01-01

    Titanium alloys possess good corrosion properties, high temperature stability and high strength-to-weight ratio. However, they fall short in providing the optimum strength-ductility relation in the most demanding structural applications, including the aerospace sector. Inspired by the possibility of enhancing the strength-ductility relation in steels through the TRIP effect, the thesis elucidates at: i) identifying and quantifying the key factors that effectively control and/or promote such e...

  15. Characterization of microstructures induced in the workpiece of aluminum alloy by excimer laser micromachining

    Energy Technology Data Exchange (ETDEWEB)

    Wu Ye [Shenzhen Key Lab of Laser Engineering, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060 (China); Li, Irene Ling, E-mail: liling@szu.edu.cn [Shenzhen Key Lab of Laser Engineering, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060 (China); Fu Ling; Zhai Jianpang; Ruan Shuangchen [Shenzhen Key Lab of Laser Engineering, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060 (China)

    2009-09-15

    Excimer laser emitting at 248 nm is applied to produce microstructures on the surface of aluminum alloy. The surface morphology shows that hotspots and thermal fluidic structures both come to light. Two possible mechanisms of hotspots formation are proposed: near-field diffraction and interference, and extremely fast rapid thermal annealing. And for the formation of thermal fluidic pattern structure, a thin film model is applied.

  16. Single and multiple trapping of radiation-induced defects in AgZn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maury, F.; Lucasson, P.; Lucasson, A.; Vajda, P.; Balanzat, E.; Beretz, D.; Halbwachs, M.; Hillairet, J.

    1984-06-01

    Experimental results on the recovery spectra of low temperature electron irradiated pure Ag and AgZn alloys in the concentration range 0.018 to 30 at.% of zinc are presented. Their comparison leads to consider two distinct concentration domains. In the low concentration domain the classical model of Corbett, Smith and Walker applies with some modifications. The resistivity recovery is governed by the combinations and annihilations of point defects. It must be noted that even in dilute alloys, new kinds of point defects (such as mixed interstitials) arise from the presence of solute atoms. In the high concentration domain, the resistivity recovery is dominated by the setting in of short-range order as a result of the point defect migration: interstitial migration in stage II and, mainly, vacancy migration in stage III. The defect migration, free in the pure metal, is influenced, in the concentrated alloys, by the local environment. The proposed model consistently allows the interpretation of the existing results, particularly from electron microscopy.

  17. Single and multiple trapping of radiation-induced defects in AgZn alloys

    International Nuclear Information System (INIS)

    Experimental results on the recovery spectra of low temperature electron irradiated pure Ag and AgZn alloys in the concentration range 0.018 to 30 at.% of zinc are presented. Their comparison leads to consider two distinct concentration domains. In the low concentration domain the classical model of Corbett, Smith and Walker applies with some modifications. The resistivity recovery is governed by the combinations and annihilations of point defects. It must be noted that even in dilute alloys, new kinds of point defects (such as mixed interstitials) arise from the presence of solute atoms. In the high concentration domain, the resistivity recovery is dominated by the setting in of short-range order as a result of the point defect migration: interstitial migration in stage II and, mainly, vacancy migration in stage III. The defect migration, free in the pure metal, is influenced, in the concentrated alloys, by the local environment. The proposed model consistently allows the interpretation of the existing results, particularly from electron microscopy. (author)

  18. High Magnetic Field-Induced Formation of Banded Microstructures in Lamellar Eutectic Alloys During Directional Solidification

    Science.gov (United States)

    Li, Xi; Fautrelle, Yves; Gagnoud, Annie; Ren, Zhongming; Moreau, Rene

    2016-06-01

    The influences of high magnetic field (up to 12 T) on the morphology of Pb-Sn and Al-Al2Cu lamellar eutectics during directional solidification were investigated. The experimental results indicate that, along with a decrease in eutectic spacing, the banded structure forms at lower growth speeds under high magnetic field and the band spacing decreases as the magnetic field increases. Moreover, the application of a magnetic field enriches the Cu solute in the liquid ahead of the liquid/solid interface during directional solidification of an Al-Al2Cu eutectic alloy. The effects of high magnetic field on the eutectic points of non-ferromagnetic alloys and the stress acting on the eutectic lamellae during directional solidification have been studied. Both thermodynamic evaluation and DTA measurements reveal that the high magnetic field has a negligible effect on the eutectic points of non-ferromagnetic alloys. However, the high magnetic field caused an increase of the nucleation temperature and undercooling. The numerical results indicate that a considerable stress is produced on the eutectic lamellae during directional solidification under high magnetic field. The formation of a banded structure in a lamellar eutectic during directional solidification under high magnetic field may be attributed to both the buildup of the solute in the liquid ahead of the liquid/solid interface and the stress acting on the eutectic lamellae.

  19. Microstructural development inside the stress induced martensite variant in a Ti-Ni-Nb shape memory alloy

    International Nuclear Information System (INIS)

    The microstructural development inside the stress induced martensite (SIM) variants in Ti-Ni-Nb alloy with various degrees of deformation have been revealed by electron microscopic observations. The orientation relationship between the SIM and the parent phase has been found: [1bar 10]Mparallel[11bar 1]B2, (001)M 5degree away from (101)B2. The lattice invariant shear of the SIM variants at the slightly deformed stage is dominantly (11bar 1) Type I twin. Besides the ordinary slip, the adjustment and development of the internal secondary twinning from (11bar 1) Type I twin to langle011rangle Type II/ or (011) Type I twin, (001)compound twin and (111) Type I twin happen concurrently or in combination inside the SIM variants with the further deformation. The corresponding deformation mechanisms include stress induced reorientation of SIM substructural bands by the most favorably oriented twin system, stress induced migration of the SIM substructural boundary through internal twinning and stress induced injection of foreign SIM variant to the preexisting substructural bands

  20. Structural evolution of alloy 800 induced by thermal aging and their consequences of the mechanical properties of the material

    International Nuclear Information System (INIS)

    One of the main characteristics of alloy 800 (used for steam generators of LMFBR reactors), an austenitic stainless steel containing Ni: 33%, Cr: 21% and addition of titanium and aluminium, is its susceptibility to secondary hardening by formation of γ' precipitates Ni3(Ti,Al). The very first stages of this precipitation have been studied using X ray diffraction and dilatometry techniques. It has been shown that the γ' phase appears during the first 500 hours between 500 and 6500C, without any time of incubation. The γ' precipitation leads to a decrease in the parameter of the austenitic matrix, this phenomena being more important with a higher (Ti+Al) content. In addition, the γ' formation induce an increase in the tensile properties at room temperature, of alloy 800 higher with a higher Ti content. Experimental results allow to drawn a graph expressing the threshold of the γ' apparition as a function of temperature. Finally, it has been shown by electronic micrography studies, that the mean radius of the particles (which remain under 200 A) follows a cubic law type r3 = Kt. The activate energy of the phenomena is about 250 KJ.mole-1

  1. The effect of ion flux on plasma-induced modification and deuterium retention in tungsten and tungsten–tantalum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zayachuk, Y., E-mail: yevhen.zayachuk@materials.ox.ac.uk [SCK-CEN, Trilateral Euregio Cluster, Boeretang 200, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, St. Pietersnieuwstraat 41, 9000 Ghent (Belgium); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Manhard, A. [Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching (Germany); Hoen, M.H.J. ' t [FOM Institute DIFFER, Trilateral Euregio Cluster, Edisonbaan 14, 3439 MN Nieuwegein (Netherlands); Jacob, W. [Max Planck Institute for Plasma Physics, Boltzmannstrasse 2, 85748 Garching (Germany); Zeijlmans van Emmichoven, P.A. [FOM Institute DIFFER, Trilateral Euregio Cluster, Edisonbaan 14, 3439 MN Nieuwegein (Netherlands); Aviation Academy, Amsterdam University of Applied Sciences, Weesperzijde 190, 1097 DZ Amsterdam (Netherlands); Van Oost, G. [Department of Applied Physics, Ghent University, St. Pietersnieuwstraat 41, 9000 Ghent (Belgium)

    2015-09-15

    The paper presents the results of an experimental study of deuterium retention in W and W–Ta alloy that were exposed to first-wall relevant low flux (∼10{sup 20} m{sup −2} s{sup −1}) deuterium plasma in the ECR plasma generator PlaQ. Subsequent analysis included surface imaging by optical microscopy, deuterium depth profiling by nuclear reaction analysis (NRA) and measurements of deuterium content by thermal desorption spectroscopy (TDS). It was found that under investigated exposure conditions the deuterium content was higher in W–Ta alloy than in W. Combined with the previously reported results showing that under high-flux (∼10{sup 24} m{sup −2} s{sup −1}) retention is higher in W instead, this gives rise to a peculiar flux effect – dependence of relative retention between different materials on exposure flux. We interpret this effect as evidence that at different flux ranges different populations of trapping sites determine the retention, namely pre-existing microstructural traps at low-flux exposure and plasma-induced ones at high-flux exposure.

  2. Preferential Au precipitation at deformation-induced defects in Fe–Au and Fe–Au–B–N alloys

    International Nuclear Information System (INIS)

    Highlights: • Fe–Au–B–N forms a good model alloy system for self healing of deformation damage. • Solute Au atoms exclusively precipitate at grain boundaries, cracks and cavities. • XPS indicates a strong tendency for Au segregation on free surfaces at 550 °C. • Interstitial B and N form hexagonal BN on free surfaces at 550 °C. • Selective Au precipitation at open volume defects can cause autonomous repair. -- Abstract: The influence of deformation-induced defects on the isothermal precipitation of Au was studied in high-purity Fe–Au and Fe–Au–B–N alloys. Preferential Au precipitation upon annealing at 550 °C is observed at local plastic indentations. In fractured Fe–Au–B–N, solute Au atoms were found to heterogeneously precipitate at grain boundaries and local micro-cracks. This is supported by in-situ creep tests that showed a strong tendency for Au precipitation at cracks and cavities also formed during creep loading at 550 °C. Complementary X-ray photoelectron spectroscopy experiments indicate a strong tendency of Au, B and N segregation onto free surface during aging. The observed site-specific precipitation of Au holds interesting opportunities for defect healing in steels subjected to creep deformation

  3. M(o)ssbauer study of the field induced uniaxial anisotropy in electro-deposited FeCo alloy films

    Institute of Scientific and Technical Information of China (English)

    Li Zhi-Wei; Yang Xu; Wang Hai-Bo; Liu Xin; Li Fa-Shen

    2009-01-01

    Thin ferromagnetic films with in-plane magnetic anisotropy are promising materials for obtaining high microwave permeability. The paper reports a M(o)ssbauer study of the field induced in-plane uniaxial anisotropy in electro-deposited FeCo alloy films. The FeCo alloy films were prepared by the electro-deposition method with and without an external magnetic field applied parallel to the film plane during deposition, Vibrating sample magnetometry and M(o)ssbauer spectroscopy measurements at room temperature indicate that the film deposited in external field shows an in-plane uniaxial anisotropy with an easy direction coinciding with the external field direction and a hard direction perpendicular to the field direction, whereas the film deposited without external field does not show any in-plane anisotropy. M(o)ssbauer spectra taken in three geometric arrangements show that the magnetic moments are almost constrained in the film plane for the film deposited with applied magnetic field. Also, the magnetic moments tend to align in the direction of the applied external magnetic field during deposition, indicating that the observed anisotropy should be attributed to directional ordering of atomic pairs.

  4. Effects of B2 precipitate size on transformation-induced plasticity of Cu–Zr–Al glassy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, C.N. [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Huang, J.C., E-mail: jacobc@mail.nsysu.edu.tw [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Li, J.B.; Jang, J.S.C. [Institute of Materials Science and Engineering, Department of Mechanical Engineering, National Central University, Chung-Li, Taiwan, ROC (China); Lin, C.H. [Department of Mechanical and Electromechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Nieh, T.G. [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States)

    2014-03-25

    Highlights: • This paper addresses the effects of the CuZr B2 size and distribution on plasticity. • There is a critical size to induce the martensitic/twinning transformation. • An analytic model based on melt flow dynamics is settled. -- Abstract: To demonstrate the effect of processing on the microstructure and subsequent mechanical property of bulk metallic glasses, we prepared two alloys, Cu{sub 47.5}Zr{sub 47.5}Al{sub 5} and Cu{sub 47.5}Zr{sub 48}Al{sub 4}Co{sub 0.5}, using two different designs of suction mold – one with a sharp inlet and one with a blunt inlet. The two alloys have been demonstrated previously to be ductile via phase transformation of the B2 phase and twin formation during plastic deformation. Microstructures of the as-cast as well plastically deformed samples, in particular, the size and distribution of the B2 phase, were examined using X-ray diffraction, scanning and transmission electron microscopy. Compressive tests were conducted on samples cast by different molds and their properties were found to closely correlate with the B2 morphology. Fluid dynamics during suction casting was also analyzed. Effects of Vena contracta, flow velocity, and Reynolds number were discussed and compared favorably with experimental observations.

  5. Cobalt-alloy implant debris induce HIF-1α hypoxia associated responses: a mechanism for metal-specific orthopedic implant failure.

    Directory of Open Access Journals (Sweden)

    Lauryn Samelko

    Full Text Available The historical success of orthopedic implants has been recently tempered by unexpected pathologies and early failures of some types of Cobalt-Chromium-Molybdenum alloy containing artificial hip implants. Hypoxia-associated responses to Cobalt-alloy metal debris were suspected as mediating this untoward reactivity at least in part. Hypoxia Inducible Factor-1α is a major transcription factor involved in hypoxia, and is a potent coping mechanism for cells to rapidly respond to changing metabolic demands. We measured signature hypoxia associated responses (i.e. HIF-1α, VEGF and TNF-α to Cobalt-alloy implant debris both in vitro (using a human THP-1 macrophage cell line and primary human monocytes/macrophages and in vivo. HIF-1α in peri-implant tissues of failed metal-on-metal implants were compared to similar tissues from people with metal-on-polymer hip arthroplasties, immunohistochemically. Increasing concentrations of cobalt ions significantly up-regulated HIF-1α with a maximal response at 0.3 mM. Cobalt-alloy particles (1 um-diameter, 10 particles/cell induced significantly elevated HIF-1α, VEGF, TNF-α and ROS expression in human primary macrophages whereas Titanium-alloy particles did not. Elevated expression of HIF-1α was found in peri-implant tissues and synovial fluid of people with failing Metal-on-Metal hips (n = 5 compared to failed Metal-on-Polymer articulating hip arthroplasties (n = 10. This evidence suggests that Cobalt-alloy, more than other metal implant debris (e.g. Titanium alloy, can elicit hypoxia-like responses that if unchecked can lead to unusual peri-implant pathologies, such as lymphocyte infiltration, necrosis and excessive fibrous tissue growths.

  6. Hydrogen induced dis-proportionation studies on Zr-Co-M (M=Ni, Fe, Ti) ternary alloys

    International Nuclear Information System (INIS)

    The intermetallic compound ZrCo is considered as a suitable material for storage, supply and recovery of hydrogen isotopes in International Thermonuclear Experimental Reactor (ITER). However, upon repeated hydriding-dehydriding cycles, the hydrogen storage capacity of ZrCo decreases, which is attributed to the disproportionate reaction ZrCo + H2 ↔ ZrH2 + ZrCo2. The reduction of hydrogen storage capacity of ZrCo is not desirable for its use in tritium facilities. In our previous studies, attempts were made to improve the durability of ZrCo against dis-proportionation by including a third element. The present study is aimed to investigate the hydrogen induced dis-proportionation of Zr-Co-M (M=Ni, Fe and Ti) ternary alloys under hydrogen delivery conditions

  7. Analysis of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-Ray Emission

    Directory of Open Access Journals (Sweden)

    Alyssa A. Frey

    2011-01-01

    Full Text Available The elemental composition of electrodeposited NiFe thin films was analyzed with particle-induced X-ray emission (PIXE. The thin films were electrodeposited on polycrystalline Au substrates from a 100 mM NiSO4, 10 mM FeSO4, 0.5 M H3BO3, and 1 M Na2SO4 solution. PIXE spectra of these films were analyzed to obtain relative amounts of Ni and Fe as a function of deposition potential and deposition time. The results show that PIXE can measure the total deposited metal in a sample over at least four orders of magnitude with similar fractional uncertainties. The technique is also sensitive enough to observe the variations in alloy composition due to sample nonuniformity or variations in deposition parameters.

  8. Structural Origin of the Enhanced Glass-Forming Ability Induced by Microalloying Y in the ZrCuAl Alloy

    Directory of Open Access Journals (Sweden)

    Gu-Qing Guo

    2016-03-01

    Full Text Available In this work, the structural origin of the enhanced glass-forming ability induced by microalloying Y in a ZrCuAl multicomponent system is studied by performing synchrotron radiation experiments combined with simulations. It is revealed that the addition of Y leads to the optimization of local structures, including: (1 more Zr-centered and Y-centered icosahedral-like clusters occur in the microstructure; (2 the atomic packing efficiency inside clusters and the regularity of clusters are both enhanced. These structural optimizations help to stabilize the amorphous structure in the ZrCuAlY system, and lead to a high glass-forming ability (GFA. The present work provides an understanding of GFAs in multicomponent alloys and will shed light on the development of more metallic glasses with high GFAs.

  9. Stress-induced Curie temperature increase in the Fe{sub 64}Ni{sub 36} invar alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gorria, Pedro; Martinez-Blanco, David; Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo (Spain); Boada, Roberto; Chaboy, Jesus [ICMA and Departamento de Fisica de la Materia Condensada, CSIC - Universidad de Zaragoza (Spain); Fernandez-Martinez, Alejandro [LGIT, University of Grenoble and CNRS, Maison des Geosciences, Grenoble (France); Institut Laue-Langevin, Grenoble (France); Garbarino, Gaston; Castro, German R.; Mezouar, Mohamed [European Synchrotron Radiation Facility (ESRF), Grenoble (France); Smith, Ronald I. [ISIS Facility, RAL, Chilton, Didcot, Oxon (United Kingdom); Alonso, J.I.G. [Department of Physical and Analytical Chemistry, University of Oviedo (Spain); Hernando, Antonio [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, Madrid (Spain)

    2009-05-15

    Structural and magnetic changes on invar Fe{sub 64}Ni{sub 36} alloy (T{sub C}=500 K) produced by mechanical milling followed by heating up to 1073 K, were investigated by neutron diffraction, magnetization measurements, X-ray diffraction under high pressures and X-ray absorption at both Fe and Ni K-edges. We argue that the strain induced in the Fe{sub 64}Ni{sub 36} material after this treatment mainly affects the Fe sites due to the magnetovolume coupling, the most notorious feature being the increase of the Curie temperature ({delta}T{sub C}=70 K). (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Shock wave induced martensitic transformations and morphology changes in Fe-Pd ferromagnetic shape memory alloy thin films

    Science.gov (United States)

    Bischoff, A. J.; Arabi-Hashemi, A.; Ehrhardt, M.; Lorenz, P.; Zimmer, K.; Mayr, S. G.

    2016-04-01

    Combining experimental methods and classical molecular dynamics (MD) computer simulations, we explore the martensitic transformation in Fe70Pd30 ferromagnetic shape memory alloy thin films induced by laser shock peening. X-ray diffraction and scanning electron microscope measurements at shock wave pressures of up to 2.5 GPa reveal formation of martensitic variants with preferred orientation of the shorter c-axis of the tetragonal unit cell perpendicular to the surface plane. Moreover, consequential merging of growth islands on the film surface is observed. MD simulations unveil the underlying physics that are characterized by an austenite-martensite transformation with a preferential alignment of the c-axis along the propagation direction of the shock wave, resulting in flattening and in-plane expansion of surface features.

  11. X-ray diffraction study of thermally and stress-induced phase transformations in single crystalline Ni-Mn-Ga alloys

    International Nuclear Information System (INIS)

    Using in-situ single crystal X-ray diffraction methods, thermally- and stress-induced crystal structure evolution was investigated in two Ni-Mn-Ga Heusler-type alloys. For the 51at.%Ni-24at.%Mn-25at.%Ga alloy it was found that application of external stress in a temperature range ∼20 C above the Ms at first causes intensity changes of X-ray diffuse scattering peaks in β-phase. Further stressing results in stress-induced phase transformations and under the appropriate conditions three successive martensitic transformations (one is parent-to-martensite and two are martensite-to-martensite transformations) can be stress induced. Of these only the parent-to-martensite transformation can be thermally-induced. Two successive structural transformations (thermally-induced parent-to-martensite and stress-induced martensite-to-martensite transformations) were found in 52at.%Ni-25at.%Mn-23at.%Ga alloy. Crystal structure, lattice parameters, type of modulation, and the length of modulation period for all martensites were identified. (orig.)

  12. Heat Capacity and Enthalpy of Fusion of Crystalline Pyrimethanil Decylate (C22 H33 N3 O2)

    Institute of Scientific and Technical Information of China (English)

    SUN Xiao-hong; LIU Yuan-fa; TAN Zhi-cheng; WANG Mei-han; JIA Ying-qi

    2005-01-01

    Low-temperature heat capacities of pyrimethanil decylate (C22 H33 N3 O2) were precisely measured with an automated adiabatic calorimeter over the temperature range from 78 to 373 K. The sample was observed to melt at(311.04 ±0.06) K. The molar enthalpy and entropy of fusion as well as the chemical purity of the compound were determined The extrapolated melting temperature for the absolutely pure compound obtained from fractional melting experiments is (311.204±0.035) K.

  13. Quench-induced precipitates in Al–Si alloys: Calorimetric determination of solute content and characterisation of microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, Philipp, E-mail: philipp.schumacher@uni-rostock.de [University of Rostock, Faculty of Mechanical Engineering and Marine Technology, Chair of Materials Science, Albert-Einstein-Str. 2, 18051 Rostock (Germany); University of Rostock, Institute of Physics, Polymer Physics Group, Wismarsche Str. 43-45, 18051 Rostock (Germany); Pogatscher, Stefan, E-mail: stefan.pogatscher@mat.ethz.ch [ETH Zurich, Department of Materials, Laboratory of Metal Physics and Technology, Vladimir-Prelog-Weg 4, 8093 Zurich (Switzerland); Starink, Marco J., E-mail: m.j.starink@soton.ac.uk [University of Southampton, Engineering and the Environment, Highfield, SO17 1BJ Southampton (United Kingdom); Schick, Christoph, E-mail: christoph.schick@uni-rostock.de [University of Rostock, Institute of Physics, Polymer Physics Group, Wismarsche Str. 43-45, 18051 Rostock (Germany); Mohles, Volker, E-mail: mohles@imm.rwth-aachen.de [RWTH Aachen University, Institute of Physical Metallurgy and Metal Physics, Kopernikusstr. 14, 52056 Aachen (Germany); Milkereit, Benjamin, E-mail: benjamin.milkereit@uni-rostock.de [University of Rostock, Faculty of Mechanical Engineering and Marine Technology, Chair of Materials Science, Albert-Einstein-Str. 2, 18051 Rostock (Germany); University of Rostock, Institute of Physics, Polymer Physics Group, Wismarsche Str. 43-45, 18051 Rostock (Germany); University of Southampton, Engineering and the Environment, Highfield, SO17 1BJ Southampton (United Kingdom)

    2015-02-20

    Highlights: • A new DSC method gives access to the entire cooling rate range of physical interest. • Two precipitation reactions were identified during cooling of pure binary Al–Si. • A physical model for solute and precipitation fraction is presented and validated. • The model allows to control phase transformations by heat treatments. • This enables to produce and mechanically test targeted microstructures. - Abstract: The present study introduces an experimental approach to investigate mechanical properties of well-defined non-equilibrium states of Al–Si alloys during cooling from solution annealing. The precipitation behaviour of binary Al–Si alloys during the cooling process has been investigated in a wide cooling rate range (2–0.0001 K/s) with differential scanning calorimetry (DSC). To access the low cooling rate range close to equilibrium an indirect DSC measurement method is introduced. Based on the enthalpy change measured by DSC a physically-based model for the calculation of remaining solute Si amount as function of temperature and cooling rate is presented. Microstructural analyses via light optical microscopy, scanning electron microscopy, atom probe tomography and X-ray diffraction have been performed to evaluate the introduced model and for information on cooling rate dependent precipitate formation. It was found that quench-induced particles of different morphology are formed during cooling. Thermomechanical analyses on clearly distinct undercooled Al–Si states show that flow stress during cooling is dependent on temperature as well as cooling rate. The mechanical behaviour is therefore influenced by solute Si content and quench-induced precipitates.

  14. Study of neutron induced outgassing from tungsten alloy for ATLAS FCAL

    CERN Document Server

    Leroy, C; Cheplakov, A P; Golikov, V; Golubyh, S M; Kulagin, E; Kukhtin, V; Luschikov, V

    1999-01-01

    The use of sintered tungsten alloy slugs as absorber in the ATLAS Forward Calorimeter (FCAL) raised concern that it could possibly poison the liquid argon during the detector operation in the hard radiation environment expected at LHC. A vacuum container filled with tungsten slugs was exposed to the fast neutron fluence of 1.5$\\cdot$10$^{16}$~n~cm$^{-2}$ at the IBR-30 reactor of JINR, Dubna. The residual gas pressure was analysed. The study was completed by mass spectrometer measurements. An upper limit value of 0.1~ppm was determined for the pollution of liquid argon in FCAL due to outgassing from tungsten slugs under irradiation.

  15. Spectroscopic analysis of element concentrations in aluminum alloy using nanosecond laser-induced breakdown spectroscopy

    Science.gov (United States)

    Luo, Wenfeng; Tang, Jie; Gao, Cunxiao; Wang, Haojing; Zhao, Wei

    2010-06-01

    A plasma generated by 1064 nm Nd:YAG laser irradiation of aluminum alloy in air at atmospheric pressure was studied spectroscopically. The electron density was inferred by measuring the Stark broadened line profile of Cu(I) 324.75 nm, while the electron temperature was determined using the Boltzmann plot method with ten neutral iron lines. Based on the results, local thermodynamic equilibrium was studied. Moreover, calibration curves were presented for samples containing Si, Fe, Cu, Mn, Mg, Ni, Zn and Ti, and the limit of detection of trace elements was calculated based on experimental results.

  16. High field alloy, thermoelectric, and mm wave studies of the field induced superconducting state in λ-(BETS)2FexGa1-xCl4

    International Nuclear Information System (INIS)

    Alloy studies in the π - d organic conductor λ-(BETS)2FexGa1-xCl4 have given new insight into the nature of field induced superconductivity (FISC), since the mechanism of the FISC involves cancellation of the π - d exchange field by the external field. Alloying on the FexGa1-x site allows tuning of the exchange field, thereby influencing the FISC phase boundary. A brief review of the low temperature phases are given, and new high magnetic field thermoelectric and mm wave results that probe the low temperature ground state are presented. (author)

  17. The inhibiting effect of dislocation helices on the stress-induced orientation of S' precipitates in Al–Cu–Mg alloy

    International Nuclear Information System (INIS)

    The phenomenon of restrained stress-induced preferential orientation of S′ precipitates is investigated using a single-crystal of Al–1.23Cu–0.43 Mg alloy. Al–1.23Cu–0.43 Mg single-crystal specimens are subjected to stress aging, and the microstructure is analyzed by transmission electron microscopy (TEM). It is found that the stress-induced preferential orientation of S′ precipitates is restrained owing to the dislocations produced by a higher stress. The effect of dislocations on the oriented precipitates depends on the total length of the intersection lines for precipitate habit planes and dislocation glide planes. This investigation not only provides important insight into solving the anisotropy problem attributed to precipitation strengthening, but also offers a benchmark for choosing the appropriate stress range in manufacturing of Al–Cu–Mg alloys. - Highlights: • Single crystals of an Al–Cu–Mg alloy were prepared for the investigations. • A phenomenon of restrained stress-induced preferential orientation of S′ precipitates was found. • The influence of dislocation helices on precipitation during stress-aging was studied. • Difference of orientation degree of S′ precipitates and θ′ precipitates was explained. • A basis for choosing the appropriate stress range in manufacturing of Al–Cu–Mg alloys is provided

  18. The inhibiting effect of dislocation helices on the stress-induced orientation of S' precipitates in Al–Cu–Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaobin [School of Materials Science and Engineering, Central South University, Changsha (China); Deng, Yunlai, E-mail: luckdeng@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha (China); State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha (China); Zhang, Jin [State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha (China); Light Alloy Research Institute, Central South University, Changsha (China); Zhang, Xinming [School of Materials Science and Engineering, Central South University, Changsha (China); State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha (China)

    2015-09-15

    The phenomenon of restrained stress-induced preferential orientation of S′ precipitates is investigated using a single-crystal of Al–1.23Cu–0.43 Mg alloy. Al–1.23Cu–0.43 Mg single-crystal specimens are subjected to stress aging, and the microstructure is analyzed by transmission electron microscopy (TEM). It is found that the stress-induced preferential orientation of S′ precipitates is restrained owing to the dislocations produced by a higher stress. The effect of dislocations on the oriented precipitates depends on the total length of the intersection lines for precipitate habit planes and dislocation glide planes. This investigation not only provides important insight into solving the anisotropy problem attributed to precipitation strengthening, but also offers a benchmark for choosing the appropriate stress range in manufacturing of Al–Cu–Mg alloys. - Highlights: • Single crystals of an Al–Cu–Mg alloy were prepared for the investigations. • A phenomenon of restrained stress-induced preferential orientation of S′ precipitates was found. • The influence of dislocation helices on precipitation during stress-aging was studied. • Difference of orientation degree of S′ precipitates and θ′ precipitates was explained. • A basis for choosing the appropriate stress range in manufacturing of Al–Cu–Mg alloys is provided.

  19. Atomic-resolution study of homogeneous radiation-induced precipitation in a neutron-irradiated W-10 at. % Re alloy. MSC report No. 5014

    International Nuclear Information System (INIS)

    The phenomenon of radiation-induced precipitation has been investigated in a W-10 at. % Re alloy using the atom-probe field-ion microscope. Results show a significant alteration of the microstructure of this alloy as a result of the fast-neutron irradiation. Precipitates with the composition approx. WRe (sigma phase) were detected at a density of 1016 cm-3. Coherent, semicoherent and possibly incoherent precipitates of the sigma phase have been observed. They were not associated with either linear or planar defects, or with any impurity atoms; i.e. a true homogeneous radiation-induced precipitation occurs in this alloy. A physical argument is presented for the nucleation of the sigma phase precipitates in the vicinity of displacement cascades produced by primary knock-on atoms. It is suggested that the nucleation of the sigma phase is due to the formation of tightly-bound mobil mixed dumbells which react to form an immobile rhenium cluster. The growth of this cluster into a precipitate is most likely driven by the irreversible vacancy: self-interstitial atom (SIA) annihilation reaction, as suggested recently by Cauvin and Martin. A mechanism for the suppression of voids, in this alloy, is presented which is self-consistent with the homogeneous radiation-induced precipitation mechanism

  20. An experimental study of microstructure-induced ultrasonic signal fluctuations in jet-engine titanium alloys

    International Nuclear Information System (INIS)

    Ultrasonic echoes from identical defects in a metal component will vary due to the influence of the local microstructure in which each defect is embedded. Two effects are responsible: (1) the scattering of sound at nearby crystallite boundaries results in 'grain noise' which is superimposed on the defect echo; and (2) the intervening microstructure modulates or distorts the sonic field that is incident on the defect, thus modifying its echo. Both effects can be significant in engine titanium alloys, and both influence inspection reliability. In this work, a series of experiments is performed to investigate signal fluctuations primarily arising from the second effect. Arrays of nominally identical no. 1 flat-bottomed holes (FBHs) in Ti-17 and Ti 6-4 specimens are scanned using a 10-MHz, broadband, focused transducer. The peak echo amplitude of each FBH in the array is measured, and the ratio of the standard deviation of the peak amplitudes to their mean serves as a dimensionless measure of the fluctuation level. Similar measurements are performed on a fine-grained nickel specimen that serves as a reference. The fluctuation level and the apparent average ultrasonic attenuation are measured as functions of alloy, propagation direction, frequency, and inspection water path (i.e., degree of beam focusing). In addition, beam distortions are studied by analyzing the sizes and shapes of the C-scan images of the FBHs. - Specimens used in this work were supplied by the Engine Titanium Consortium under the Federal Aviation Administration Grant No. 94-G-048

  1. An experimental study of microstructure-induced ultrasonic signal fluctuations in jet-engine titanium alloys

    Science.gov (United States)

    Margetan, Frank J.; Wasan, Harpreet; Thompson, R. Bruce

    2000-05-01

    Ultrasonic echoes from identical defects in a metal component will vary due to the influence of the local microstructure in which each defect is embedded. Two effects are responsible: (1) the scattering of sound at nearby crystallite boundaries results in "grain noise" which is superimposed on the defect echo; and (2) the intervening microstructure modulates or distorts the sonic field that is incident on the defect, thus modifying its echo. Both effects can be significant in engine titanium alloys, and both influence inspection reliability. In this work, a series of experiments is performed to investigate signal fluctuations primarily arising from the second effect. Arrays of nominally identical #1 flat-bottomed holes (FBHs) in Ti-17 and Ti 6-4 specimens are scanned using a 10-MHz, broadband, focused transducer. The peak echo amplitude of each FBH in the array is measured, and the ratio of the standard deviation of the peak amplitudes to their mean serves as a dimensionless measure of the fluctuation level. Similar measurements are performed on a fine-grained nickel specimen that serves as a reference. The fluctuation level and the apparent average ultrasonic attenuation are measured as functions of alloy, propagation direction, frequency, and inspection water path (i.e., degree of beam focusing). In addition, beam distortions are studied by analyzing the sizes and shapes of the C-scan images of the FBHs.—Specimens used in this work were supplied by the Engine Titanium Consortium under the Federal Aviation Administration Grant No. 94-G-048.

  2. Surface nanocrystallization of 7A04 aluminium alloy induced by circulation rolling plastic deformation

    Institute of Scientific and Technical Information of China (English)

    YE Hui-qiong; FAN Xin-min

    2006-01-01

    The surface nanocrystalline microstructures of 7A04 aluminium alloy was obtained by means of circulation rolling plastic deformation(CRPD),the grain refinement behavior and the hardness variation were examined. X-ray diffraction(XRD) and transmission electron microscopy(TEM) were applied to characterize the microstructure of the surface layer. The experimental evidences show that,after the CRPD treatment,the mean grain size in the surface layer is about 50 nm. The microhardness of the nanostructured surface layers is enhanced significantly after CRPD compared with that of the matrix,which can be attributed primarily to the grain refinement. The microhardness at the top surface can reach about HV0.05335,while the value of the matrix is HV0.05160 or so. The surface hardening effect is obtained obviously. Besides,the thermal stability of nanocrystalline layer was investigated. The results of the XRD analysis and the microhardness measurement show that the nanocrystalline layer has better thermal-stability than the matrix. And the DSC measurement shows that the synthesis of nanostructured surface layer has influence on the phase transformation of 7A04 aluminum alloy.

  3. PIXE from thin films and amorphous alloys induced by medium energy heavy ions

    International Nuclear Information System (INIS)

    Highlights: •Low energy heavy-ion PIXE were used for surface characterization. •It was performed in time sequence and at grazing incidence-exit geometry. •Stability of thin films against implantation and interface mixing was analyzed. •Sputtering of multicomponent alloys subjected to irradiation was monitored. -- Abstract: Characteristic X-rays emitted under impact of fast light ions with surfaces (PIXE) provide information not only on atomic excitation and further recombination processes but also on elemental composition and dynamics of restructuration of the surface. In this work radiation emitted during interaction of medium energy (∼200 keV) heavy ions (Ar, N) with Si (1 1 0) surface and with Fe/Si and Fe/Cu/Si thin (1–50 nm) films in grazing incidence-exit angle geometry were measured in time sequence in order to show that dynamics of selective modification of surface structure and composition can be monitored in-situ with PIXE. It is shown that surfaces of amorphous alloys are not stable against heavy ions (HI) irradiation due to preferential sputtering and implantation and that the dynamics of such modification can also be monitored with PIXE. The method is used for example to find detection limit for implanted Ar ions

  4. In situ EBSD investigations of the asymmetric stress-induced martensitic transformation in TiNi shape memory alloys under bending

    Energy Technology Data Exchange (ETDEWEB)

    Mao, S.C. [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100022 (China); Han, X.D. [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100022 (China)], E-mail: xdhan@bjut.edu.cn; Tian, Y.B.; Luo, J.F.; Zhang, Z.; Ji, Y. [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100022 (China); Wu, M.H. [Advanced Materials Technology, Edwards Lifesciences LLC, CA 92614-5688 (United States)

    2008-12-20

    An inverse pole figure with tensile-compressive asymmetric Schmid factor (SF) was developed for TiNi shape memory alloys. The stress-induced martensitic transformation behaviors in polycrystalline TiNi alloys were directly visualized and mapped by in situ electron backscatter diffraction (EBSD) technique. The results clearly show that the stress-induced martensitic transformations sustaining tensile and compressive stresses are asymmetric. The observed results are well interpreted by the Schmid factor inverse pole figure (SFIPF). It was also suggested that the internal stress distribution, the inter-grain accommodation and the constrained effect on the polycrystalline system are additional factors impacting the formation and selection of stress-induced SF habit plane martensitic variants.

  5. In situ EBSD investigations of the asymmetric stress-induced martensitic transformation in TiNi shape memory alloys under bending

    International Nuclear Information System (INIS)

    An inverse pole figure with tensile-compressive asymmetric Schmid factor (SF) was developed for TiNi shape memory alloys. The stress-induced martensitic transformation behaviors in polycrystalline TiNi alloys were directly visualized and mapped by in situ electron backscatter diffraction (EBSD) technique. The results clearly show that the stress-induced martensitic transformations sustaining tensile and compressive stresses are asymmetric. The observed results are well interpreted by the Schmid factor inverse pole figure (SFIPF). It was also suggested that the internal stress distribution, the inter-grain accommodation and the constrained effect on the polycrystalline system are additional factors impacting the formation and selection of stress-induced SF habit plane martensitic variants

  6. Stress-induced martensitic transformation in (Ni47Ti44)100-xNbx shape memory alloys with wide hysteresis

    Institute of Scientific and Technical Information of China (English)

    HE Xiang-ming; ZHAO Long-zhi; DUO Shu-wang; ZHANG Rong-fa; RONG Li-jian

    2006-01-01

    The effect of deformation via stress-induced martensitic transformation on the reverse transformation behavior of the (Ni47Ti44)100-xNbx (x=3,9,15,20,30,mole fraction,%) shape memory alloys was investigated in detail by differential scanning calorimetry (DSC) after performing cryogenic tensile tests at a temperature of Ms+30 ℃. The results show that Nb-content has obvious effect on the process of stress-induced martensitic transformation. It is also observed that the stress-induced martensite is stabilized relative to the thermally-induced martensite (TIM) formed on cooling,and Nb-content in Ni-Ti-Nb alloy has great influence on the reverse transformation start temperature and transformation temperature hysteresis of stress-induced martensite(SIM). The mechanism of wide transformation temperature hysteresis was fully explained based on the microscopic structure and the distribution of the elastic strain energy of (Ni47Ti44)100-xNbx alloys.

  7. On the widths of the hysteresis of mechanically and thermally induced martensitic transformations in Ni-Ti-based shape memory alloys

    International Nuclear Information System (INIS)

    It is well known that a good crystallographic compatibility between austenite and martensite in Ni-Ti-based shape memory alloys results in narrow thermal hystereses (e.g. Ball and James, Arch. Ration. Mech. Anal., 1987). The present work suggests that a good crystallographic fit is moreover associated with a small mechanical hysteresis width, observed during a forward and reverse stress-induced transformation. Furthermore, shape memory alloys with a good crystallographic fit show smaller transformation strains. The results obtained in the present study suggest that these correlations are generic and apply to binary Ni-Ti (with varying Ni contents) and quaternary Ni-Ti-Cu-X (X = Cr, Fe, V) alloys. For binary Ni-Ti, it was observed that Ni-rich compositions (good lattice fit) show a lower accumulation of irreversible strains during pseudoelastic cycling.

  8. On the widths of the hysteresis of mechanically and thermally induced martensitic transformations in Ni-Ti-based shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, Stefanie; Maass, Burkhard; Frenzel, Jan; Schmidt, Marvin; Ullrich, Johannes; Seelecke, Stefan; Schuetze, Andreas; Kastner, Oliver; Eggeler, Gunther [Bochum Univ. (Germany). Inst. fuer Werkstoffe

    2015-10-15

    It is well known that a good crystallographic compatibility between austenite and martensite in Ni-Ti-based shape memory alloys results in narrow thermal hystereses (e.g. Ball and James, Arch. Ration. Mech. Anal., 1987). The present work suggests that a good crystallographic fit is moreover associated with a small mechanical hysteresis width, observed during a forward and reverse stress-induced transformation. Furthermore, shape memory alloys with a good crystallographic fit show smaller transformation strains. The results obtained in the present study suggest that these correlations are generic and apply to binary Ni-Ti (with varying Ni contents) and quaternary Ni-Ti-Cu-X (X = Cr, Fe, V) alloys. For binary Ni-Ti, it was observed that Ni-rich compositions (good lattice fit) show a lower accumulation of irreversible strains during pseudoelastic cycling.

  9. Inhibition of caustic induced stress corrosion cracking of Alloy 600 by inhibitors

    International Nuclear Information System (INIS)

    The effect of inhibitors on the electrochemical behavior and the stress corrosion cracking resistance of Alloy 600 was evaluated in 10% sodium hydroxide solution at 315.deg.C. The C-ring specimens for stress corrosion cracking test were polarized at 150 mV above the corrosion potential for 120 hours with and without inhibitors such as titanium oxide, titanium boride and cerium boride. The chemical compositions of the films formed on the crack tip in the C-ring specimens were analyzed using scanning Auger electron spectroscopy. The cerium boride, the most effective inhibitor, was observed to decrease the crack propagation rate by more than a factor of three compared with that obtained in a no inhibitor solution. It was found that the changes of the active-passive transition potentials and the film compositions were related to the resistance to stress corrosion cracking in high temperature caustic solutions

  10. Ion-induced swelling of ODS ferritic alloy MA957 tubing to 500 dpa

    Energy Technology Data Exchange (ETDEWEB)

    Toloczko, M.B., E-mail: mychailo.toloczko@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Garner, F.A. [Radiation Effects Consulting, Richland, WA 99354 (United States); Voyevodin, V.N.; Bryk, V.V.; Borodin, O.V.; Mel’nychenko, V.V.; Kalchenko, A.S. [Kharkov Institute of Physics and Technology, Kharkov (Ukraine)

    2014-10-15

    In order to study the potential swelling behavior of the ODS ferritic alloy MA957 at very high dpa levels, specimens were prepared from pressurized tubes that were unirradiated archives of tubes previously irradiated in FFTF to doses as high as 110 dpa. These unirradiated specimens were irradiated with 1.8 MeV Cr{sup +} ions to doses ranging from 100 to 500 dpa and examined by transmission electron microscopy. No co-injection of helium or hydrogen was employed. It was shown that compared to several tempered ferritic/martensitic steels irradiated in the same facility, these tubes were rather resistant to void swelling, reaching a maximum value of only 4.5% at 500 dpa and 450 °C. In this fine-grained material, the distribution of swelling was strongly influenced by the presence of void denuded zones along the grain boundaries.

  11. Ion-induced swelling of ODS ferritic alloy MA957 tubing to 500 dpa

    Science.gov (United States)

    Toloczko, M. B.; Garner, F. A.; Voyevodin, V. N.; Bryk, V. V.; Borodin, O. V.; Mel'nychenko, V. V.; Kalchenko, A. S.

    2014-10-01

    In order to study the potential swelling behavior of the ODS ferritic alloy MA957 at very high dpa levels, specimens were prepared from pressurized tubes that were unirradiated archives of tubes previously irradiated in FFTF to doses as high as 110 dpa. These unirradiated specimens were irradiated with 1.8 MeV Cr+ ions to doses ranging from 100 to 500 dpa and examined by transmission electron microscopy. No co-injection of helium or hydrogen was employed. It was shown that compared to several tempered ferritic/martensitic steels irradiated in the same facility, these tubes were rather resistant to void swelling, reaching a maximum value of only 4.5% at 500 dpa and 450 °C. In this fine-grained material, the distribution of swelling was strongly influenced by the presence of void denuded zones along the grain boundaries.

  12. Biologically-Induced Micropitting of Alloy 22, a Candidate Nuclear Waste Packaging Material

    International Nuclear Information System (INIS)

    The effects of potential microbiologically influenced corrosion (MIC) on candidate packaging materials for nuclear waste containment are being assessed. Coupons of Alloy 22, the outer barrier candidate for waste packaging, were exposed to a simulated, saturated repository environment (or microcosm) consisting of crushed rock (tuff) from the Yucca Mountain repository site and a continual flow of simulated groundwater for periods up to five years at room temperature and 30 C. Coupons were incubated with YM tuff under both sterile and non-sterile conditions. Surfacial analysis by scanning electron microscopy of the biotically-incubated coupons show development of both submicron-sized pinholes and pores; these features were not present on either sterile or untreated control coupons. Room temperature, biotically-incubated coupons show a wide distribution of pores covering the coupon surface, while coupons incubated at 30 C show the pores restricted to polishing ridges

  13. Radiation-induced evolution of austenite matrix in silicon-modified AISI 316 alloys

    International Nuclear Information System (INIS)

    The microstructures of a series of silicon-modified AISI 316 alloys irradiated to fast neutron fluences of about 2-3 and 10 x 1022 n/cm2 (E > 0.1 MeV at temperatures ranging from 4000C to 6000C have been examined. The irradiation of AISI 316 leads to an extensive repartition of several elements, particularly nickel and silicon, between the matrix and various precipitate phases. The segregation of nickel at void and grain boundary surfaces at the expense of other faster-diffusing elements is a clear indication that one of the mechanisms driving the microchemical evolution is the Inverse Kirkendall effect. There is evidence that at one sink this mechanism is in competition with the solute drag process associated with interstitial gradients

  14. Induced effects in Fe-Ni-Cr austenitic alloys by electron irradiation

    International Nuclear Information System (INIS)

    Materials behaviour under high energetic particles exposure has to be know for technological aspects, but also for microscopic material state physics. Large macroscopic investigations have been developed but reliability with theoretical calculations or fundamental physics measurements is not clear. We present four experimental procedures in order to characterize austenitic Fe-Ni-Cr synthetic alloys in the atomic scale. First, results obtained about vacancy and interstitial, after electrical resistivity measurements and monoenergetical or classical positron annihilation process, are discussed. Then, defects clustering and microstructural evolution is investigated using positron lifetime measurements and high resolution electronic microscopy. In this study, special care has been taken to understand the composition effect as a function of the irradiation conditions

  15. In vivo apatite formation induced on titanium metal and its alloys by chemical treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kokubo, T.; Kim, H.M. [Kyoto Univ. (Japan). Dept. of Material Chemistry; Nishiguchi, S.; Nakamura, T. [Kyoto Univ. (Japan). Dept. of Orthopaedic Surgery

    2001-07-01

    NaOH and heat treatments form an amorphous sodium titanate layer with a graded structure on the surfaces of titanium metal and its alloys. These treatments give no adverse effect on mechanical properties of the metals. Thus treated metals form an apatite layer on their surfaces in the living body by taking the calcium and phosphate ions from the surrounding fluid. This apatite layer is tightly integrated to the metal substrates through a graded structure, and bonds to the living bone in a short period, because of its structure and composition analogous to those of the bone mineral. This kind of bioactive metals are believed to be useful as bone substitutes even under load bearing conditions such as hip joints and dental implants. (orig.)

  16. Experimental characterisation and modelling of deformation- induced microstructure in an A6061 aluminium alloy

    Science.gov (United States)

    Kreyca, J. F.; Falahati, A.; Kozeschnik, E.

    2016-03-01

    For industry, the mechanical properties of a material in form of flow curves are essential input data for finite element simulations. Current practice is to obtain flow curves experimentally and to apply fitting procedures to obtain constitutive equations that describe the material response to external loading as a function of temperature and strain rate. Unfortunately, the experimental procedure for characterizing flow curves is complex and expensive, which is why the prediction of flow-curves by computer modelling becomes increasingly important. In the present work, we introduce a state parameter based model that is capable of predicting the flow curves of an A6061 aluminium alloy in different heat-treatment conditions. The model is implemented in the thermo-kinetic software package MatCalc and takes into account precipitation kinetics, subgrain formation, dynamic recovery by spontaneous annihilation and dislocation climb. To validate the simulation results, a series of compression tests is performed on the thermo-mechanical simulator Gleeble 1500.

  17. Corrosion product formation during NaCl induced atmospheric corrosion of magnesium alloy AZ91D

    International Nuclear Information System (INIS)

    Magnesium alloy AZ91D was exposed in humid air at 95% relative humidity (RH) with a deposition of 70 μg/cm-2 NaCl. The corrosion products formed and the surface electrolyte were analysed after different exposure times using ex situ and in situ FTIR spectroscopy, X-ray diffraction and Ion Chromatography. The results show that magnesium carbonates are the main solid corrosion products formed under these conditions. The corrosion products identified were the magnesium carbonates hydromagnesite (Mg5 (CO3)4 (OH)24H2O) and nesquehonite (MgCO3 3H2O). The corrosion attack starts with the formation of magnesite at locations with higher NaCl contents. At 95% RH, a sequence of reactions was observed with the initial formation of magnesite, which transformed into nesquehonite after 2-3 days. Long exposures result in the formation of pits containing brucite (Mg(OH2)) covered with hydromagnesite crusts. The hydromagnesite crusts restrict the transport of CO2 and O2 to the magnesium surface and thereby favour the formation of brucite. Analysis of the surface electrolyte showed that the NaCl applied on the surface at the beginning was essentially preserved during the initial corrosion process. Since the applied salt was not bound in sparingly soluble corrosion products a layer of NaCl electrolyte was present on the surface during the whole exposure. Thus, Na+ and Cl- ions can participate in the corrosion process during the whole time and the availability of these species will not restrict the atmospheric corrosion of AZ91D under these conditions. It is suggested that the corrosion behaviour of AZ91D is rather controlled by factors related to the microstructure of the alloy and formation of solid carbonate containing corrosion products blocking active corrosion sites on the surface

  18. Corrosion product formation during NaCl induced atmospheric corrosion of magnesium alloy AZ91D

    Energy Technology Data Exchange (ETDEWEB)

    Joensson, Martin [Corrosion and Metals Research Institute (KIMAB), Drottning Kristinas vaeg 48, SE-114 28 Stockholm (Sweden)]. E-mail: martin.jonsson@kimab.com; Persson, Dan [Corrosion and Metals Research Institute (KIMAB), Drottning Kristinas vaeg 48, SE-114 28 Stockholm (Sweden); Thierry, Dominique [Institut de la Corrosion, 220 Rue Rivoalon, 29200 Brest (France)

    2007-03-15

    Magnesium alloy AZ91D was exposed in humid air at 95% relative humidity (RH) with a deposition of 70 {mu}g/cm{sup -2} NaCl. The corrosion products formed and the surface electrolyte were analysed after different exposure times using ex situ and in situ FTIR spectroscopy, X-ray diffraction and Ion Chromatography. The results show that magnesium carbonates are the main solid corrosion products formed under these conditions. The corrosion products identified were the magnesium carbonates hydromagnesite (Mg{sub 5} (CO{sub 3}){sub 4} (OH){sub 2}4H{sub 2}O) and nesquehonite (MgCO{sub 3} 3H{sub 2}O). The corrosion attack starts with the formation of magnesite at locations with higher NaCl contents. At 95% RH, a sequence of reactions was observed with the initial formation of magnesite, which transformed into nesquehonite after 2-3 days. Long exposures result in the formation of pits containing brucite (Mg(OH{sub 2})) covered with hydromagnesite crusts. The hydromagnesite crusts restrict the transport of CO{sub 2} and O{sub 2} to the magnesium surface and thereby favour the formation of brucite. Analysis of the surface electrolyte showed that the NaCl applied on the surface at the beginning was essentially preserved during the initial corrosion process. Since the applied salt was not bound in sparingly soluble corrosion products a layer of NaCl electrolyte was present on the surface during the whole exposure. Thus, Na{sup +} and Cl{sup -} ions can participate in the corrosion process during the whole time and the availability of these species will not restrict the atmospheric corrosion of AZ91D under these conditions. It is suggested that the corrosion behaviour of AZ91D is rather controlled by factors related to the microstructure of the alloy and formation of solid carbonate containing corrosion products blocking active corrosion sites on the surface.

  19. In-situ high-energy X-ray diffraction investigation on stress-induced martensitic transformation in Ti-Nb binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chang, L. L.; Wang, Y. D.; Ren, Y.

    2016-01-10

    Microstructure evolution, mechanical behaviors of cold rolled Ti-Nb alloys with different Nb contents subjected to different heat treatments were investigated. Optical microstructure and phase compositions of Ti-Nb alloys were characterized using optical microscopy and X-ray diffractometre, while mechanical behaviors of Ti-Nb alloys were examined by using tension tests. Stress-induced martensitic transformation in a Ti-30. at%Nb binary alloy was in-situ explored by synchrotron-based high-energy X-ray diffraction (HE-XRD). The results obtained suggested that mechanical behavior of Ti-Nb alloys, especially Young's modulus was directly dependent on chemical compositions and heat treatment process. According to the results of HE-XRD, α"-V1 martensite generated prior to the formation of α"-V2 during loading and a partial reversible transformation from α"-V1 to β phase was detected while α"-V2 tranformed to β completely during unloading.

  20. Effect of irradiation temperature on crystallization of {alpha}-Fe induced by He irradiations in Fe{sub 80}B{sub 20} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    San-noo, Toshimasa; Toriyama, Tamotsu; Wakabayashi, Hidehiko; Iijima, Hiroshi [Musashi Inst. of Tech., Tokyo (Japan); Hayashi, Nobuyuki; Sakamoto, Isao

    1997-03-01

    Since amorphous alloys are generally highly resistant to irradiation and their critical radiation dose is an order of magnitude higher for Fe-B amorphous alloy than Mo-methods, these alloys are expected to become applicable as for fusion reactor materials. The authors investigated {alpha}-Fe crystallization in an amorphous alloy, Fe{sub 80}B{sub 20} using internal conversion electron Moessbauer spectroscopy. The amount of {alpha}-Fe component was found to increase by raising the He-irradiation dose. The target part was modified to enable He ion radiation at a lower temperature (below 400 K) by cooling with Peltier element. Fe{sub 80}B{sub 20} amorphous alloy was cooled to keep the temperature at 300 K and exposed to 40 keV He ion at 1-3 x 10{sup 8} ions/cm{sup 2}. The amount of {alpha}-Fe crystal in each sample was determined. The crystal formation was not observed for He ion radiation below 2 x 10{sup 18} ions/cm{sup 2}, but that at 3 x 10{sup 8} ions/ cm{sup 2} produced a new phase ({delta} +0.40 mm/sec, {Delta} = 0.89 mm/sec). The decrease in the radiation temperature from 430 to 300 K resulted to extremely repress the production of {alpha}-Fe crystal, suggesting that the crystallization induced by He-radiation cascade is highly depending on the radiation temperature. (M.N.)

  1. The influence of pre-irradiation heat treatments on thermal non-equilibrium and radiation-induced segregation behavior in model austenitic stainless steel alloys

    International Nuclear Information System (INIS)

    The effect of pre-irradiation heat treatments on thermal non-equilibrium grain boundary segregation (TNES) and subsequent radiation-induced grain boundary segregation (RIS) is studied in a series of model austenitic stainless steels. The alloys used for this study are based on AISI 316 stainless steel and have the following nominal compositions: Fe-16Cr-13Ni-1.25Mn (base 316), Fe-16Cr-13Ni-1.25Mn-2.0Mo (316+ Mo) and Fe-16Cr-13Ni-1.25Mn-2.0Mo-0.07P (316+ Mo+ P). Samples were heat treated at temperatures ranging from 1100 to 1300 C and cooled at 4 different rates (salt brine quench, water quench, air cool and furnace cool) to evaluate the effect of annealing temperature and quench rate on TNES. The alloys were than processed with the treatment (temperature and cooling rate) that resulted in the maximum Cr enrichment. Alloys with and without the heat treatment to enrich the grain boundaries with Cr were characterized following irradiation to 1 dpa at 400 C with high-energy protons in order to understand the influence of alloying additions and pre-irradiation grain boundary chemistry on irradiation-induced elemental enrichment and depletion profiles. Various mechanistic models will be examined to explain the observed behavior

  2. Metal-induced artifacts in computed tomography and magnetic resonance imaging: comparison of a biodegradable magnesium alloy versus titanium and stainless steel controls

    International Nuclear Information System (INIS)

    To evaluate metal artifacts induced by biodegradable magnesium - a new class of degradable biomaterial that is beginning to enter the orthopedic routine - on CT and MRI compared to standard titanium and steel controls. Different pins made of titanium, stainless steel, and biodegradable magnesium alloys were scanned using a second-generation dual-energy multidetector CT and a 1.5-T MR scanner. In CT, quantitative assessment of artifacts was performed by two independent readers by measuring the noise in standardized regions of interest close to the pins. In MRI, the artifact diameter was measured. Interobserver agreement was evaluated using intraclass correlation coefficients. Artifacts were compared using Mann Whitney U tests. In comparison to stainless steel, biodegradable magnesium alloys induced significantly fewer artifacts in both 1.5-T MRI (p = 0.019-0.021) and CT (p = 0.003-0.006). Compared to titanium, magnesium induced significantly less artifact-related noise in CT (p = 0.003-0.008). Although artifacts were less on MRI for biodegradable magnesium compared to titanium, this result was not statistically significant. Biodegradable magnesium alloys induce substantially fewer artifacts in CT compared to standard titanium and stainless steel, and fewer artifacts in MRI for the comparison with stainless steel. (orig.)

  3. Metal-induced artifacts in computed tomography and magnetic resonance imaging: comparison of a biodegradable magnesium alloy versus titanium and stainless steel controls

    Energy Technology Data Exchange (ETDEWEB)

    Filli, Lukas [University Hospital Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); University Hospital Zurich, Department of Radiology, Zurich (Switzerland); Luechinger, Roger [University and ETH Zurich, Institute for Biomedical Engineering, Zurich (Switzerland); Frauenfelder, Thomas; Guggenberger, Roman; Farshad-Amacker, Nadja; Andreisek, Gustav [University Hospital Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); Beck, Stefan [Synthes GmbH, Zuchwil (Switzerland)

    2015-06-01

    To evaluate metal artifacts induced by biodegradable magnesium - a new class of degradable biomaterial that is beginning to enter the orthopedic routine - on CT and MRI compared to standard titanium and steel controls. Different pins made of titanium, stainless steel, and biodegradable magnesium alloys were scanned using a second-generation dual-energy multidetector CT and a 1.5-T MR scanner. In CT, quantitative assessment of artifacts was performed by two independent readers by measuring the noise in standardized regions of interest close to the pins. In MRI, the artifact diameter was measured. Interobserver agreement was evaluated using intraclass correlation coefficients. Artifacts were compared using Mann Whitney U tests. In comparison to stainless steel, biodegradable magnesium alloys induced significantly fewer artifacts in both 1.5-T MRI (p = 0.019-0.021) and CT (p = 0.003-0.006). Compared to titanium, magnesium induced significantly less artifact-related noise in CT (p = 0.003-0.008). Although artifacts were less on MRI for biodegradable magnesium compared to titanium, this result was not statistically significant. Biodegradable magnesium alloys induce substantially fewer artifacts in CT compared to standard titanium and stainless steel, and fewer artifacts in MRI for the comparison with stainless steel. (orig.)

  4. Relaxation studies of amorphous alloys with creep induced magnetic and structural anisotropy

    International Nuclear Information System (INIS)

    Amorphous ferromagnetic (Fe,Co,Ni) ribbons of various compositions have been prepared by rapid solidification and annealed with applied tensile stress. This process yields both creep-induced magnetic anisotropy and structural anisotropy. Post-annealing has been done to investigate the relaxation process. X-ray diffraction and thermomechanical analysis measurement of post-annealed samples reveal a clear underlying relaxation process in the material, proving that structural anisotropy corresponds to the elastic strain induced by creep annealing.

  5. Electromagnetic Gauge Study of Laser-Induced Shock Waves in Aluminium Alloys

    Science.gov (United States)

    Peyre, P.; Fabbro, R.

    1995-12-01

    The laser-shock behaviour of three industrial aluminum alloys has been analyzed with an Electromagnetic Gauge Method (EMV) for measuring the velocity of the back free surface of thin foils submitted to plane laser irradiation. Surface pressure, shock decay in depth and Hugoniot Elastic Limits (HEL) of the materials were investigated with increasing thicknesses of foils to be shocked. First, surface peak pressures values as a function of laser power density gave a good agreement with conventional piezoelectric quartz measurements. Therefore, comparison of experimental results with computer simulations, using a 1D hydrodynamic Lagrangian finite difference code, were also in good accordance. Lastly, HEL values were compared with static and dynamic compressive tests in order to estimate the effects of a very large range of strain rates (10^{-3} s^{-1} to 10^6 s^{-1}) on the mechanical properties of the alloys. Cet article fait la synthèse d'une étude récente sur la caractérisation du comportement sous choc-laser de trois alliages d'aluminium largement utilisés dans l'industrie à travers la méthode dite de la jauge électromagnétique. Cette méthode permet de mesurer les vitesses matérielles induites en face arrière de plaques d'épaisseurs variables par un impact laser. La mise en vitesse de plaques nous a permis, premièrement, de vérifier la validité des pressions d'impact superficielles obtenues en les comparant avec des résultats antérieurs obtenus par des mesures sur capteurs quartz. Sur des plaques d'épaisseurs croissantes, nous avons caractérisé l'atténuation des ondes de choc en profondeur dans les alliages étudiés et mesuré les limites d'élasticité sous choc (pressions d'Hugoniot) des alliages. Les résultats ont été comparés avec succès à des simulations numériques grâce à un code de calcul monodimensionnel Lagrangien. Enfin, les valeurs des pressions d'Hugoniot mesurées ont permis de tracer l'évolution des contraintes d

  6. Pressure-magnetic field induced phase transformation in Ni46Mn41In13 Heusler alloy

    International Nuclear Information System (INIS)

    The effect of hydrostatic pressure and magnetic field on the magnetic properties and phase transformation in Ni46Mn41In13 Heusler alloy was investigated. Pressure (P)-magnetic field (H)-temperature (T) phase diagram has been constructed from experimental results. In the P–T contour of the phase diagram, the slope of the austenite-martensite phase boundary line appears positive (dT/dP > 0), while it appears negative (dT/dH < 0) in the H–T contour. The results revealed that pressure and magnetic field have opposite effect on phase stabilization. The combined effect of pressure and magnetic field on martensitic transition has led to two important findings: (i) pressure dependent shift of austenite start temperature (As) is higher when larger field is applied, and (ii) field dependent shift of As is lowered when a higher pressure is applied. The pressure and magnetic field dependent shift observed in the martensitic transformation has been explained on the basis of thermodynamic calculations. Curie temperature of the phases was found to increase with pressure at a rate of 0.6 K/kbar

  7. Cool-down induced hydride reorientation of hydrogen-charged Zirconium alloy cladding tubes

    International Nuclear Information System (INIS)

    250 and 500ppm hydrogen-charged Zirconium alloy tubes were employed to investigate hydride reorientation behaviors when they were cool down from 400 to 300, 200degC and room temperature with various cooling rates of 0.3, 2.0, 4.0, 7.0 and 15.0degC/min under a tensile hoop stress of 150MPa. These cool-down tests indicate that the slower cooling rate and the lower terminal cool-down temperature produced the more hydrides precipitated along with the larger fraction and the longer length of radial hydrides. These phenomena may be explained by terminal solid solubility of hydrogen for dissolution and precipitation and cooling rate-dependent hydride nucleation and growth rates. On the other hand, a dramatic decrease of ultimate tensile strength and plastic strain of the cool-down tested specimens may be explained by the amount of the radial hydrides precipitated during the cool-down process. (author)

  8. Ion irradiation induced modifications of nanostructured Ni-Mn-Sn ferromagnetic shape memory alloy thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vishnoi, R. [Functional Nanomaterials Research Laboratory, Department of Physics, IIT Roorkee, Roorkee (India); Singhal, R.; Asokan, K.; Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Kaur, D., E-mail: dkaurfph@iitr.ernet.in [Functional Nanomaterials Research Laboratory, Department of Physics, IIT Roorkee, Roorkee (India)

    2011-12-30

    Thin films of Ni-Mn-Sn ferromagnetic shape memory alloy, grown on Si substrate by DC magnetron sputtering were bombarded by 450 keV Ar{sup +4} ions at different fluences ranging from 1 Multiplication-Sign 10{sup 14} to 3 Multiplication-Sign 10{sup 16} ions/cm{sup 2} in order to investigate the effect of ion irradiation on characteristic transformation temperatures and thus on shape memory behavior. Temperature dependent resistivity measurements reveal the increase in martensitic transformation temperature ({approx} 100 K) upto a fluence of 1 Multiplication-Sign 10{sup 15} ions/cm{sup 2}, above which shape memory behavior degrades and completely loses its behavior at 3 Multiplication-Sign 10{sup 16} ions/cm{sup 2}, which is ascribed to the amorphization of Ni-Mn-Sn structure at a fluence of 3 Multiplication-Sign 10{sup 16} ions/cm{sup 2} as evidenced from X-ray diffraction pattern. The diffuse rings in the electron diffraction pattern also confirmed the amorphization of the film at highest fluence. The temperature dependent magnetization measurements also show the increase in martensitic transformation temperature upto a fluence of 1 Multiplication-Sign 10{sup 15} ions/cm{sup 2} in support of resistivity data. This work gives a possibility to acquire a better control on the properties of FSMA thin films using ion irradiation.

  9. Chemical alloying induced collapse of reversibility windows in ternary As-S-I glasses*

    Science.gov (United States)

    Wang, Fei; Boolchand, P.

    2006-03-01

    Thermally reversing windows represent glass compositions across which glass transitions are thermally reversing in character. These windows have been observed in several chalcogenide glasses, and are identified^1 with self-organized phases of glassy networks. Upon alloying halogen (iodine) in base chalcogenide glasses (Ge-Se, Ge-S), the reversibility windows collapse^2 about the mean-field rigidity transition. We attempt to understand this behavior better. We have now synthesized ternary glass compositions of the type, (AsI3)x(As0.30S0.70)1-x and (AsI3)y (As2S3)1-y over wide composition ranges of x and y, and have examined them systematically in Raman scattering and MDSC experiments. Along with earlier results^3 on binary AszS1-z glasses, the present results permit mapping the reversibility window over the glass forming range of the present As-S-I ternary. The results show the window region to be of nearly triangular shape, with a base extending in the 0.20 85,3823 (2005). 2. Y. Wang et al. Phys. Rev. Lett. 87, 18, 5503 (2001) 3. D.G. Georgiev, Ph.D. Thesis , Univ. of Cincinnati (2003) unpublished

  10. Molecular dynamics study on interaction between irradiation induced defects and dislocation in BCC Iron alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Jae Hyeok; Kim, Ji Woo; Lee, Gil Jae [KAIST, Daejeon (Korea, Republic of)

    2007-02-15

    We performed the MD simulations with modified version of the MDCASK code with many-body interatomic potentials by Ackland for the assesment of mobility of dislocation with temperature, the interaction between defects, SiA loops and Cu precipitate and dislocation in BCC iron alloys. The effect of a helium atom on the migration of self-interstitial dislocation loops with a Burgers vector 1/2<111> in bcc Fe has been investigated using molecular statics and molecular dynamics simulations. It is found that an interstitial He atom hinders the migration and coalescence behavior of dislocation loops by strongly binding to the loop on the edge sites. An unstable interstitial He atom on the loop plane easily moves to the stable edge sites by interstitial diffusion. A substitutional He atom does not significantly disturb the migration of dislocation loops, showing weak binding. Molecular dynamics simulations of the interaction between a screw dislocation and a coherent bcc Cu precipitate in bcc Fe indicate that the screw dislocation stress field assists a martensitic transformation into a close-packed structure for precipitate diameters larger than 1.8 nm, resulting in a stronger obstacle to dislocation glide. The observed martensitic transformation mechanism agrees with the Nishiyama-Kajiwara model. For coherent bcc Cu precipitates with diameter larger than 2.5 nm, the screw dislocation bypass mechanism becomes Orowan looping due to the coherency loss of the precipitates during the transformation

  11. Identical mechanism of isochronal and isothermal embrittlement in Ni(Bi) alloy: Thermo-induced non-equilibrium grain-boundary segregation of Bi

    International Nuclear Information System (INIS)

    Highlights: • Both isochronal and isothermal plasticity of Ni(Bi) alloy show minima. • Existing interpretations for isochronal and isothermal embrittlement are inadequate. • Both embrittlement is caused by thermo-induced non-equilibrium grain-boundary segregation of Bi. - Abstract: Isochronal and isothermal plasticity after thermal pre-treatments are obtained by tensile tests to characterize the embrittling behaviors of Ni(Bi) alloy. Both isochronal and isothermal plasticity show evident minima. Fractography observed by scanning electron microscopy displays intergranular fracture for samples of low plasticity. The microstructure is found to be free of precipitates within grains and at grain boundaries by focused ion beam and transmission electron microscopy. Atom probe analysis indicates a strong tendency of Bi segregation to grain boundaries. By these results, the existing interpretations are discussed to be inadequate and both embrittlement are confirmed to be identical in mechanism, i.e. thermo-induced non-equilibrium grain-boundary segregation of Bi

  12. Influence of radiation-induced voids and bubbles on physical properties of austenitic structural alloys

    Science.gov (United States)

    Balachov, Iouri I.; Shcherbakov, E. N.; Kozlov, A. V.; Portnykh, I. A.; Garner, F. A.

    2004-08-01

    Void swelling in austenitic stainless steels induces significant changes in their electrical resistivity and elastic moduli, as demonstrated in this study using a Russian stainless steel irradiated as fuel pin cladding in BN-600. Precipitation induced by irradiation also causes second-order changes in these properties, but can dominate the measurement for small swelling levels. When cavities are full of helium as expected under some fusion irradiation conditions, additional second-order changes are expected but they will be small enough to exclude from the analysis.

  13. Strain-induced precipitation in a Ti micro-alloyed HSLA steel

    International Nuclear Information System (INIS)

    Highlights: → Strain induces TiC precipitation in austenite. → TiC precipitation occurs on dislocations and dislocation sub-structures. → Severe deformation brings out more dislocations in steel. → Higher dislocation density results in faster kinetics of precipitation. - Abstract: The strain-induced precipitation kinetics of TiC in a 0.05% C-0.10% Ti HSLA steel was investigated by two-stage interrupted compression method. The precipitation-time-temperature (PTT) diagram for TiC precipitation was obtained by analyzing the softening kinetics curves of deformed austenite, which was confirmed to be of validity by employing transmission electron microscopy (TEM). Experimental results showed that the PTT diagram for TiC precipitation exhibited a typical 'C' shaped and the nucleation of strain-induced TiC precipitation was a very rapid process in the temperature range 900-925 deg. C. The relatively severe deformation applied on the steel was considered to be the main factor resulting in the fast kinetics of TiC precipitation. The TiC precipitates were heterogeneously distributed in either a chain-like or a cell like manner, implying that the precipitates nucleated on dislocations or on dislocation sub-structures, which were produced by deformation. The growth of TiC precipitates approximately followed a parabolic law. In addition, the coarsening of strain-induced TiC precipitates had already started before the completion of precipitation.

  14. Spin torque-induced magnetization dynamics in giant magnetoresistance devices with Heusler alloy layers

    International Nuclear Information System (INIS)

    We studied the spin torque-induced magnetization dynamics of full-Heusler Co2(Fe,Mn)Si (CFMS) layers in current-perpendicular-to-plane (CPP) giant magnetoresistance (GMR) devices, and obtained the phase diagrams of spin torque-induced phenomena such as magnetization switching and spin torque oscillation. For a device with a 3 nm-thick CFMS free layer and a 20 nm-thick CFMS fixed layer, spin torque oscillation was induced in the free layer magnetization. As the free layer thickness was increased from 3 to 7 nm, on the other hand, the magnetization dynamics were remarkably changed. A 7 nm-thick CFMS free layer showed no clear spin torque oscillation even though it showed the reversible magnetization switching. On the contrary, the magnetization in the 20 nm-thick CFMS fixed layer oscillated at a certain condition. This spin torque-induced instability in the fixed layer magnetization is attributable to the increase in the free layer thickness, the structure of the fixed layer having the extended film, and the stray field coupling between the free and the fixed layers. (paper)

  15. Strain-induced precipitation in a Ti micro-alloyed HSLA steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zhenqiang, E-mail: wangzhe19840203@163.com [Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Haidian District, Beijing 100084 (China) and Institute for Structural Materials, Central Iron and Steel Research Institute, No. 76, Xueyuan Nanlu, Beijing 100081 (China); Mao Xinping [Guangzhou Zhujiang Steel Co. Ltd, Guangzhou 510730 (China); Yang Zhigang [Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Haidian District, Beijing 100084 (China); Sun Xinjun; Yong Qilong [Institute for Structural Materials, Central Iron and Steel Research Institute, No. 76, Xueyuan Nanlu, Beijing 100081 (China); Li Zhaodong [Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Haidian District, Beijing 100084 (China); Institute for Structural Materials, Central Iron and Steel Research Institute, No. 76, Xueyuan Nanlu, Beijing 100081 (China); Weng Yuqing [Chinese Society for Metals, No. 46, Dongsixi Street, Beijing 100371 (China)

    2011-11-25

    Highlights: {yields} Strain induces TiC precipitation in austenite. {yields} TiC precipitation occurs on dislocations and dislocation sub-structures. {yields} Severe deformation brings out more dislocations in steel. {yields} Higher dislocation density results in faster kinetics of precipitation. - Abstract: The strain-induced precipitation kinetics of TiC in a 0.05% C-0.10% Ti HSLA steel was investigated by two-stage interrupted compression method. The precipitation-time-temperature (PTT) diagram for TiC precipitation was obtained by analyzing the softening kinetics curves of deformed austenite, which was confirmed to be of validity by employing transmission electron microscopy (TEM). Experimental results showed that the PTT diagram for TiC precipitation exhibited a typical 'C' shaped and the nucleation of strain-induced TiC precipitation was a very rapid process in the temperature range 900-925 deg. C. The relatively severe deformation applied on the steel was considered to be the main factor resulting in the fast kinetics of TiC precipitation. The TiC precipitates were heterogeneously distributed in either a chain-like or a cell like manner, implying that the precipitates nucleated on dislocations or on dislocation sub-structures, which were produced by deformation. The growth of TiC precipitates approximately followed a parabolic law. In addition, the coarsening of strain-induced TiC precipitates had already started before the completion of precipitation.

  16. Influence of microstructural modifications induced by ultrasonic impact treatment on hardening and corrosion behavior of wrought Co-Cr-Mo biomedical alloy.

    Science.gov (United States)

    Petrov, Yu N; Prokopenko, G I; Mordyuk, B N; Vasylyev, M A; Voloshko, S M; Skorodzievski, V S; Filatova, V S

    2016-01-01

    In this work, biomedical Co-28Cr-6Mo alloy is subjected to ultrasonic impact treatment (UIT). XRD, TEM and SAED analyses show that the plastic deformation induced by the UIT process results in a complex microstructural formation in surface layer of Co-28Cr-6Mo alloy. The peculiar feature observed in the alloy structure by TEM is the formation of Lomer-Cottrell locks originated by simultaneous sliding of Shockley partial dislocations in intersecting planes. At the beginning of the UIT process (till the strain extent e ≈ 0.2), dislocation pile-ups are gathered in front of the Lomer-Cottrell locks stimulating the formation of a great number of chaotic stacking faults (SFs) packets (incompletely transformed martensite), which are predominant with regard to the occurrence of ε-martensite and micro-twins. The incompletely transformed martensite hinders the shear translation through the twin boundaries and suppresses grain subdivision in surface layer of Co-28Cr-6Mo alloy at the UIT process used. On-going deformation to e ≈ 0.4 leads to further modification of microstructure in the micron-scale γ-grains, which consists of numerous Lomer-Cottrell locks, chaotic subtraction SFs, intersected nano-twins and fine lathes of ε-martensite with average size of approx. 50-100 nm. The observed structural features (at e ≈ 0.4) allow adequately explaining noticeable increase in microhardness without any cracks/cleavages in surface layer. Enhanced corrosion resistance of Co-28Cr-6Mo alloy, which manifests itself with less negative corrosion potential and lower corrosion and passivity currents in potentiodynamic curve, is promoted by the UIT induced oxide films and the following structural features: the CSL type of γ/ε interfacial boundaries, uniformly distributed fine carbides, and high fraction of the grains oriented with close packed (111)γ and (0002)ε planes parallel to the surface of the UIT-processed specimen. PMID:26478400

  17. Magneto-structural transitions induced at 1.2 K in Ni2MnGa-based Heusler alloys by high magnetic field up to 60 T

    International Nuclear Information System (INIS)

    The huge decrease of the martensitic transition temperature T M–A with increasing field (up to dT M–A /dH = −8.1 K T−1) was observed in all the Co-doped and In-doped Ni50 − xCo xMn25 + yGa25 − y − zIn z Heusler alloys at high pulse magnetic field up to 60 T. The structural martensitic transitions were induced at temperatures 2 K and 1.2 K in the Ni1.72Co0.28Mn1.25Ga0.75 and Ni1.65Co0.34Mn1.31Ga0.62In0.07 alloys, respectively. The transitions are accompanied by a significant increase of magnetization of their austenite phase with increasing field up to M A(2 K) = 6.3 μ B/f.u. The very slight increase of magnetization of their martensite phase M M(2 K) was induced by the high magnetic field in both, the stoichiometric Ni2MnGa and the off-stoichiometric Ni1.65Co0.34Mn1.31Ga0.62In0.07 alloys. The presented results demonstrate the key role of magnetism in the martensitic transitions in the Ni2MnGa based Heusler alloys and point to the Jahn–Teller effect as a source of the tetragonal distortion of crystal structure of these alloys. (papers)

  18. C-atom-induced bandgap modulation in two-dimensional (100) silicon carbon alloys

    Science.gov (United States)

    Mizuno, Tomohisa; Nagamine, Yoshiki; Omata, Yuhsuke; Suzuki, Yuhya; Urayama, Wako; Aoki, Takashi; Sameshima, Toshiyuki

    2016-04-01

    We experimentally studied the effects of the C atom on bandgap E G modulation in two-dimensional (2D) silicon carbon alloys, Si1- Y C Y , fabricated by hot C+ ion implantation into the (100) SOI substrate in a wide range of Y (4 × 10-5 ≤ Y ≤ 0.13), in comparison with the characteristics of 3D silicon carbide (SiC). X-ray photoelectron spectroscopy (XPS) and UV-Raman analysis confirm the Si-C, C-C, and Si-Si bonds in the 2D-Si1- Y C Y layer. The photoluminescence (PL) method shows that the E G and PL intensity I PL of 2D-Si1- Y C Y drastically increase with increasing Y for high Y (≥0.005), and thus we demonstrated a high E G of 2.5 eV and a visible wavelength λPL less than 500 nm. Even for low Y (<10-3), I PL of 2D-Si1- Y C Y also increases with increasing Y, owing to the compressive strain of the 2D-Si1- Y C Y layer caused by the C atoms, but the Y dependence of E G is very small. E G of 2D-Si1- Y C Y can be controlled by changing Y. Thus, the 2D-Si1- Y C Y technique is very promising for new E G engineering of future high-performance CMOS and Si photonics.

  19. Direct writing of CoFe alloy nanostructures by focused electron beam induced deposition from a heteronuclear precursor

    Science.gov (United States)

    Porrati, F.; Pohlit, M.; Müller, J.; Barth, S.; Biegger, F.; Gspan, C.; Plank, H.; Huth, M.

    2015-11-01

    Recently, focused electron beam-induced deposition has been employed to prepare functional magnetic nanostructures with potential in nanomagnetic logic and sensing applications by using homonuclear precursor gases like Fe(CO)5 or Co2(CO)8. Here we show that an extension towards the fabrication of bi-metallic compounds is possible by using a single-source heteronuclear precursor gas. We have grown CoFe alloy magnetic nanostructures from the HFeCo3(CO)12 metal carbonyl precursor. The compositional analysis indicates that the samples contain about 80 at% of metal and 10 at% of carbon and oxygen. Four-probe magnetotransport measurements are carried out on nanowires of various sizes down to a width of 50 nm, for which a room temperature resistivity of 43 μΩcm is found. Micro-Hall magnetometry reveals that 50 nm × 250 nm nanobars of the material are ferromagnetic up to the highest measured temperature of 250 K. Finally, the transmission electron microscopy (TEM) microstructural investigation shows that the deposits consist of a bcc Co-Fe phase mixed with a FeCo2 O4 spinel oxide phase with nanograins of about 5 nm diameter.

  20. Hydrogen-induced changes in the crystalline structure and mechanical properties of a Zn-Al eutectoid alloy rapidly solidified

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval Jimenez, Alberto; Iturbe Garcia, Jose Luis [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Estado de Mexico (Mexico)]. E-mail: alberto.sandoval@inin.gob.mx; asandovalj@correo.unam.mx; Negrete Sanchez, Jesus [Universidad Autonoma de San Luis Potosi, San Luis Potosi (Mexico); Torres Villasenor, Gabriel [Instituto de Investigaciones en Materiales, UNAM, Mexico D.F. (Mexico)

    2009-09-15

    Ribbon fractions of a zinc-aluminum eutectoid (Zn40.8Al%at.) alloy, obtained by rapid solidification using melt spinning technique, were submitted to a thermo-hydrogenation process by periods of 1, 6, 18, 24, 30, and 48 hours, to 200 degrees Celsius and 20 atmospheres. Thermo-hydrogenated samples were analyzed by transmission electron microscopy (TEM). Hydrogen-induced changes were produced, such as microstructure refining, development of crystalline defects, microhardness changes and modification of stable crystalline structures to {alpha}R meta-stable phase at room temperature. [Spanish] Fracciones de tiras de una aleacion eutectoide de zinc-aluminio (Zn40.8Al%at.), obtenidas mediante solidificacion rapida usando la tecnica de melt spinning, se sometieron a un proceso de termohidrogenacion por periodos de 1, 6, 18, 24, 30 y 48 horas, a 200 grados centigrados y 20 atmosferas. Las muestras termohidrogenadas se analizaron por microscopia electronica de transmision (MET). Se produjeron cambios inducidos por hidrogeno, tales como la refinacion de la microestructura, el desarrollo de defectos cristalinos, cambios de microdureza y modificacion de las estructuras cristalinas estables a fase metaestable {alpha}R a temperatura ambiente.

  1. Monitoring the corrosion process of Al alloys through pH induced fluorescence

    International Nuclear Information System (INIS)

    A sensing and monitoring set-up based on electrochemical pH induced fluorescence to systematically control the electrochemical corrosion process has been developed for possible applications in the field of localized corrosion. The sensing and monitoring concept is based on exposing the corroding metal surface to solutions that contain selected redox chemicals which will react in local regions where anodic or cathodic polarizations occur. Redox couples that produce or consume protons in their electrochemical reactions were used so that local pH gradients can indicate electrochemical activity by inducing fluorescence in dyes. This approach has been applied to study the corrosion initiation in aircraft aluminum metal 2024-T3 in a controlled electrochemical cell. Preliminary results obtained suggest that monitoring of localized corrosion based on pH can be achieved for field applications

  2. KCl-induced high temperature corrosion of selected commercial alloys. Part II: alumina and silica-formers

    DEFF Research Database (Denmark)

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

    2016-01-01

    potassium-chromium-silicon-oxygen containing layer forms as the innermost corrosion product. The layer was uniformly distributed over the surface and appears to render some protection as this alloy exhibited the best performance among the investigated alloys. To reveal further aspects of the corrosion...

  3. Alloying elemental change of SS-316 and Al-5754 during laser welding using real time laser induced breakdown spectroscopy (LIBS) accompanied by EDX and PIXE microanalysis

    Science.gov (United States)

    Jandaghi, M.; Parvin, P.; Torkamany, M. J.; Sabbaghzadeh, J.

    Experimental studies of pulsed laser welding of stainless steel 316 in keyhole mode was done to examine a vaporization model based on the kinetic theory of gases and the thermodynamic laws. A long pulsed Nd:YAG laser with variable duration of 1-12 ms and 9-17 Gw/cm2 was employed. The undesirable loss of volatile elements affects on the weld metal compositions and the alloy properties. The model predicts that the loss of alloying elements strongly takes place at higher peak powers and longer pulse durations. On the other hand, the model shows the rapid migration of Mn and Cr based on the pressure and concentration gradients from the molten pool. Accordingly, the concentrations of iron, chromium, nickel and manganese were determined in the weld pool by means of the energy dispersive x-ray analysis (EDX) and proton induced X ray characteristics (PIXE) microanalysis. The change of weld metal composition of aluminium alloy 5754 in keyhole mode laser welding, was investigated using the model and was supported by the successive measurements. The model predicts that the concentration of magnesium in the weld metal decreases, while the aluminium concentration increases. Moreover, the real time concentrations of aluminium and magnesium elements in the weld metal were determined by laser induced breakdown spectroscopy (LIBS) at different conditions. We conclude that variation of the Al to Mg concentration ratio is negligible with various laser power densities while it is strongly correlated to the pulse duration.

  4. An investigation of concentrated and distributed strain inducing constraints for training shape memory alloys

    Science.gov (United States)

    Parent, Pauline Marie

    Borderline personality disorder (BPD) is a severe mental illness characterized by high rates of engagement in distress-induced risk behavior. Unfortunately, extant laboratory-based risk paradigms have failed to account for the role of distress in precipitating risk behavior, so many questions remain about processes mechanisms that underlie this behavior. The current study examined affect as a moderator of the relationship between diagnostic status and risk behavior, as measured by a behavioral risk task, and affective and non-affective neurocognitive functioning as potential mediators of this relationship. Results indicated that individuals with BPD engaged in more risk behavior in the distress condition than in the neutral condition, whereas individuals without BPD showed a decrease in risk behavior across the two conditions. However, corresponding changes in executive functioning were not observed, suggesting the need for continued research to identify alternative mechanisms (e.g., neurocognitive, motivational) to explain this effect.

  5. Induction of Mitochondrial Changes Associated with Oxidative Stress on Very Long Chain Fatty Acids (C22:0, C24:0, or C26:0-Treated Human Neuronal Cells (SK-NB-E

    Directory of Open Access Journals (Sweden)

    Amira Zarrouk

    2012-01-01

    Full Text Available In Alzheimer's disease, lipid alterations point towards peroxisomal dysfunctions. Indeed, a cortical accumulation of saturated very long chain fatty acids (VLCFAs: C22:0, C24:0, C26:0, substrates for peroxisomal β-oxidation, has been found in Alzheimer patients. This study was realized to investigate the effects of VLCFAs at the mitochondrial level since mitochondrial dysfunctions play crucial roles in neurodegeneration. On human neuronal SK-NB-E cells treated with C22:0, C24:0, or C26:0 (0.1–20 μM; 48 h, an inhibition of cell growth and mitochondrial dysfunctions were observed by cell counting with trypan blue, MTT assay, and measurement of mitochondrial transmembrane potential (Δψm with DiOC6(3. A stimulation of oxidative stress was observed with DHE and MitoSOX used to quantify superoxide anion production on whole cells and at the mitochondrial level, respectively. With C24:0 and C26:0, by Western blotting, lower levels of mitochondrial complexes III and IV were detected. After staining with MitoTracker and by transmission electron microscopy used to study mitochondrial topography, mass and morphology, major changes were detected in VLCFAs treated-cells: modification of the cytoplasmic distribution of mitochondria, presence of large mitochondria, enhancement of the mitochondrial mass. Thus, VLCFAs can be potential risk factors contributing to neurodegeneration by inducing neuronal damages via mitochondrial dysfunctions.

  6. Study of local crystallization induced in FeSiNbZrB amorphous alloy by swift heavy ion (SHI) irradiation at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jianrong, E-mail: sunjr@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Zhiguang; Wang, Yuyu; Chang, Hailong; Song, Peng; Shen, Tielong; Zhu, Yabin; Pang, Lilong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Fashen [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2013-07-15

    Amorphous FeSiNbZrB alloy (metallic glass) ribbons were prepared by melt spinning and swift heavy ion (SHI) irradiation experiments were performed on the materials research terminal of the 320 kV ECR platform at the Institute of Modern Physics (IMP), Lanzhou. XRD, TEM and Mössbauer spectroscopy was used to reveal the irradiation-induced local crystallization, plastic deformation, damages and the magnetic moments rearrangements. The dimensions of our ribbons perpendicular to ion beam direction increased slightly , but the ribbon dimension along the ion beam shrunk; Irradiation of Xe-ions could cause local crystallization of amorphous FeSiNbZrB alloy ribbons and form finer α-Fe(Si) phases precipitations with diameter of 1–2 nm; SHI irradiation could make the distribution of the magnetic moments of amorphous ribbons change their orientation from the in-plane orientation to the perpendicular one.

  7. Al2O3 nanoparticles induced simultaneous refinement and modification of primary and eutectic Si particles in hypereutectic Al–20Si alloy

    International Nuclear Information System (INIS)

    Highlights: ► Size of primary Si particles decreased by 80% after addition of Al2O3 nanoparticles. ► Eutectic Si particles were also simultaneously modified by Al2O3 nanoparticles. ► Morphology of eutectic Si changed from large thin plate into coralline-like shape. ► The ductility of hypereutectic Al–20Si alloy was enhanced by 365%. - Abstract: It is well known that the mechanical properties of hypereutectic Al–Si alloys are affected by the size, volume fraction, and distribution of primary and eutectic Si particles. However, it is very difficult to simultaneously refine and modify Si particles in hypereutectic Al–Si alloys by conventional means. This study investigates an effect of nanoparticles on Si particles during solidification in hypereutectic Al–Si alloys. Various contents of γ-Al2O3 nanoparticles were added in hypereutectic Al–20Si alloy melt and further dispersed through an ultrasonic cavitation based technique. The cast hypereutectic Al–20Si alloy with the nanoparticle addition showed a significant enhancement in both strengths and ductility. The ductility of the cast hypereutectic Al–20Si alloy was increased from 0.37% to 1.72% with an addition of 0.5 wt% γ-Al2O3 nanoparticles. Yield strength and ultimate tensile strength of the nanocomposite also showed an improvement of about 6% and 26%, respectively. Study suggests that γ-Al2O3 nanoparticles effectively induced simultaneous refinement of primary Si and modification of eutectic Si, resulting in superior ductility enhancement that is much higher than that conventional methods can offer. Microstructural analysis with optical and scanning electron microscope (SEM) revealed that the primary Si particles were refined from large star shapes with small features to polygon or blocky shapes with smooth edges and corners. Moreover, the large plate eutectic Si particles were also modified into the fine coralline-like ones. The results could have great potential for numerous applications.

  8. Al{sub 2}O{sub 3} nanoparticles induced simultaneous refinement and modification of primary and eutectic Si particles in hypereutectic Al-20Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hongseok; Konishi, Hiromi [Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States); Li Xiaochun, E-mail: xcli@engr.wisc.edu [Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Size of primary Si particles decreased by 80% after addition of Al{sub 2}O{sub 3} nanoparticles. Black-Right-Pointing-Pointer Eutectic Si particles were also simultaneously modified by Al{sub 2}O{sub 3} nanoparticles. Black-Right-Pointing-Pointer Morphology of eutectic Si changed from large thin plate into coralline-like shape. Black-Right-Pointing-Pointer The ductility of hypereutectic Al-20Si alloy was enhanced by 365%. - Abstract: It is well known that the mechanical properties of hypereutectic Al-Si alloys are affected by the size, volume fraction, and distribution of primary and eutectic Si particles. However, it is very difficult to simultaneously refine and modify Si particles in hypereutectic Al-Si alloys by conventional means. This study investigates an effect of nanoparticles on Si particles during solidification in hypereutectic Al-Si alloys. Various contents of {gamma}-Al{sub 2}O{sub 3} nanoparticles were added in hypereutectic Al-20Si alloy melt and further dispersed through an ultrasonic cavitation based technique. The cast hypereutectic Al-20Si alloy with the nanoparticle addition showed a significant enhancement in both strengths and ductility. The ductility of the cast hypereutectic Al-20Si alloy was increased from 0.37% to 1.72% with an addition of 0.5 wt% {gamma}-Al{sub 2}O{sub 3} nanoparticles. Yield strength and ultimate tensile strength of the nanocomposite also showed an improvement of about 6% and 26%, respectively. Study suggests that {gamma}-Al{sub 2}O{sub 3} nanoparticles effectively induced simultaneous refinement of primary Si and modification of eutectic Si, resulting in superior ductility enhancement that is much higher than that conventional methods can offer. Microstructural analysis with optical and scanning electron microscope (SEM) revealed that the primary Si particles were refined from large star shapes with small features to polygon or blocky shapes with smooth edges and corners

  9. Intergranular brittle fracture of a low alloy steel induced by grain boundary segregation of impurities: influence of the microstructure

    International Nuclear Information System (INIS)

    The study contributes to improve the comprehension of intergranular embrittlement induced by the phosphorus segregation along prior austenitic grain boundaries of low alloy steels used in pressurized power reactor vessel. A part of this study was performed using a A533 steel which contains chemical fluctuations (ghost lines) with two intensities. Axi-symmetrically notched specimens were tested and intergranular brittle de-cohesions were observed in the ghost lines. The fracture initiation sites observed on fracture surfaces were identified as MnS inclusions. A bimodal statistic obtained in a probabilistic model of the fracture is explained by the double population of ghost lines' intensities. A metallurgical study was performed on the same class of steel by studying the influence of the microstructure on the susceptibility to temper embrittlement. Brittle fracture properties of such microstructures obtained by dilatometric experiments were tested on sub-sized specimens to measure the V-notched fracture toughness. Fraction areas of brittle fracture modes were determined on surface fractures. A transition of the fracture mode with the microstructure is observed. It is shown that tempered microstructures of martensite and lower bainite are more susceptible to intergranular embrittlement than tempered upper bainitic microstructure. The intergranular fracture is the most brittle mode. The analysis of crystalline mis-orientations shows a grain boundary structure appreciably more coherent for tempered microstructures of martensite and lower bainite. The higher density of random grain boundaries is susceptible to drag the phosphorus in the upper bainitic matrix and to make the quantity of free phosphorus decreasing. Microstructure observations show a difference in the size and the spatial distribution of carbides, essentially cementite, between tempered martensite and upper bainite. It can explain the bigger susceptibility of this last microstructure to cleavage mode

  10. Phase-field crystal study of segregation induced grain-boundary premelting in binary alloys

    International Nuclear Information System (INIS)

    The segregation-induced grain boundary (GB) premelting is studied by phase-field crystal model. We investigate the microstructure evolution of GBs with different misorientation angles and the variation of concentration distribution during premelting process. The liquid film thickness is calculated by an excessive mass technique. The results show that for low-angle GBs, the liquid phase first appears at individual dislocations region where the solute atoms segregate, and there exist two structural transitions during premelting process, which behave as two inflection points in the curve of w versus ΔB0. For high-angle GBs, the liquid film is rather uniform and its thickness diverges logarithmically when the melting point is approached. Moreover, the higher misorientation angle and segregation the GB has, the lower temperature the liquid film occurs. The concentration variation law indicates that GB segregation and GB premelting promote each other when the liquid phase appears. The critical wetting angle is almost equal to 12.5° and this value is much closer to the reality

  11. Magnetic transition induced by mechanical deformation in Fe60Al40−xSix ternary alloys

    International Nuclear Information System (INIS)

    Highlights: • Fe60Al40−xSix alloys were disordered by means of planetary ball milling technique. • Paramagnetic to ferromagnetic transition is observed with disordering. • Si addition hinders the disordering process and the increase of the lattice parameter. • Si addition promotes the paramagnetic to ferromagnetic transition. -- Abstract: We have used Mössbauer spectroscopy and X-ray diffraction to study the influence of different Al/Si ratios on the structural and magnetic properties of the mechanically deformed Fe60Al40−xSix alloys. The results indicate that ternary alloys also present the magnetic transition with disordering observed in binary Fe60Al40 alloys. Besides, Si introduction has two opposite contributions. From a structural point of view, hinders the disordering process, but, from a magnetic point of view promotes the magnetic transition

  12. Hydrogen induced stress corrosion cracks initiation to propagation process of titanium alloys under the deep underground environments

    International Nuclear Information System (INIS)

    Overpacks for high-level trans-uranium (TRU) radioactive waste must be reliable for geological disposal for as long as 60,000 years. The composite overpacks composed of a corrosion resistant Ti-Pd alloy outer layer and a carbon steel inner layer should never be subject to crevice corrosion when stored in a deep underground environment. The presumed upper limit environment of TRU waste disposal was the groundwater originated from sea water, and 80 deg. C based on the radiation resolution. Ti-0.01Pd was chosen based on the empirical crevice corrosion temperature - chloride concentration map. The critical temperature of crevice corrosion was 92 deg. C at 0.6 mol/L [NaCl] solution based on ER,CREV measurements. The corrosion resistance of weld joint was equal to that of base material. From cathodic reaction on the titanium surface for maintaining the passivity, hydrogen might be generated. Hydrogen induced stress corrosion cracks have been shown to occur. The mean titanium-hydride thickness, Hd and greatest crack depth for cross section, Cd were measured after constant-current uni-axle constant load tensile test in 0.6 mol/L [NaCl] solution at 80 deg. C. Effects of electric charge density, Q, current density, i, temperature, T, pH were examined as parameter dependence. The electric current density, which copes with hydrogen occurrence speed decreased, the Hd increased. Also Hd is clearly seen to increase with Q when Q > 1 MC/m2. No crack could be detected below Qc = 3.5 MC/m2, and above the Qc, Cd was initially increased with increases in Q. The equation Cd(μm) = 7 x (Q(MC/m2) - 3.5)0.5 holds. Based on the details heat analysis of the radiation resolution during disposal, the temperature transition was computed. From the temperature dependence of electric current density for maintaining the passivity, the amount of electric charge density of 7.5 MC/m2 for 60,000 years was calculated. From the equation above, the estimated crack depth is under 15 μm, which is as small

  13. Biochemical characterization of protein quality control mechanisms during disease progression in the C22 mouse model of CMT1A

    Directory of Open Access Journals (Sweden)

    Vinita G. Chittoor

    2013-12-01

    Full Text Available Charcot–Marie–Tooth disease type 1A (CMT1A is a hereditary demyelinating neuropathy linked with duplication of the peripheral myelin protein 22 (PMP22 gene. Transgenic C22 mice, a model of CMT1A, display many features of the human disease, including slowed nerve conduction velocity and demyelination of peripheral nerves. How overproduction of PMP22 leads to compromised myelin and axonal pathology is not fully understood, but likely involves subcellular alterations in protein homoeostatic mechanisms within affected Schwann cells. The subcellular response to abnormally localized PMP22 includes the recruitment of the ubiquitin–proteasome system (UPS, autophagosomes and heat-shock proteins (HSPs. Here we assessed biochemical markers of these protein homoeostatic pathways in nerves from PMP22-overexpressing neuropathic mice between the ages of 2 and 12 months to ascertain their potential contribution to disease progression. In nerves of 3-week-old mice, using endoglycosidases and Western blotting, we found altered processing of the exogenous human PMP22, an abnormality that becomes more prevalent with age. Along with the ongoing accrual of misfolded PMP22, the activity of the proteasome becomes compromised and proteins required for autophagy induction and lysosome biogenesis are up-regulated. Moreover, cytosolic chaperones are consistently elevated in nerves from neuropathic mice, with the most prominent change in HSP70. The gradual alterations in protein homoeostatic response are accompanied by Schwann cell de-differentiation and macrophage infiltration. Together, these results show that while subcellular protein quality control mechanisms respond appropriately to the presence of the overproduced PMP22, with aging they are unable to prevent the accrual of misfolded proteins.

  14. Enhancement of carotenoid production by disrupting the C22-sterol desaturase gene (CYP61 in Xanthophyllomyces dendrorhous

    Directory of Open Access Journals (Sweden)

    Loto Iris

    2012-10-01

    Full Text Available Abstract Background Xanthophyllomyces dendrorhous is a basidiomycetous yeast that synthesizes astaxanthin, which is a carotenoid with a great biotechnological impact. The ergosterol and carotenoid synthesis pathways are derived from the mevalonate pathway, and in both pathways, cytochrome P450 enzymes are involved. Results In this study, we isolated and described the X. dendrorhous CYP61 gene, which encodes a cytochrome P450 involved in ergosterol biosynthesis. This gene is composed of nine exons and encodes a 526 amino acid polypeptide that shares significant percentages of identity and similitude with the C22-sterol desaturase, CYP61, from other fungi. Mutants derived from different parental strains were obtained by disrupting the CYP61 gene with an antibiotic selection marker. These mutants were not able to produce ergosterol and accumulated ergosta-5,8,22-trien-3-ol and ergosta-5,8-dien-3-ol. Interestingly, all of the mutants had a more intense red color phenotype than their respective parental strains. The carotenoid composition was qualitatively and quantitatively analyzed by RP-HPLC, revealing that the carotenoid content was higher in the mutant strains without major changes in their composition. The expression of the HMGR gene, which encodes an enzyme involved in the mevalonate pathway (3-hydroxy-3-methylglutaryl-CoA reductase, was analyzed by RT-qPCR showing that its transcript levels are higher in the CYP61 mutants. Conclusions These results suggest that in X. dendrorhous, ergosterol regulates HMGR gene expression by a negative feedback mechanism and in this way; it contributes in the regulation of the carotenoid biosynthesis.

  15. Use of conventional electrochemical techniques to produce crystalline FeRh alloys induced by Ag seed layer

    International Nuclear Information System (INIS)

    Highlights: •Production of FeRh alloys by electrodeposition. •Use of Ag seed layer causes crystallization in electrodeposited Fe20Rh80 alloy. •Mössbauer spectroscopy indicates that the FeRh/Ag alloy has a long range atomic order structure. -- Abstract: By combining galvanic displacement and electrodeposition techniques, an ordered Fe20Rh80 structure deposited onto brass was investigated by X-ray diffractometry, Mössbauer spectroscopy and magnetization measurements. Mössbauer and X-ray diffraction analyses suggest that the Fe–Rh alloy directly electrodeposited onto brass displays a nanocrystalline state while a similar alloy deposited onto Ag/brass shows a faced centered cubic-like structure, with dendrites-like features. These results directly indicate that the presence of Ag seed layer is responsible for the Fe–Rh alloy crystallization process. In addition, room temperature Mössbauer data indicate firstly paramagnetic states for two Fe-species. In the dominant Fe-species (major fraction of the Mössbauer spectra), Fe atoms are situated at a cubic environment and it can be attributed to the γ-Fe20Rh80 alloy based on their hyperfine parameters. In the second species, Fe atoms are placed in a non-local symmetry, which can be related to Fe atoms at the grain boundaries or/and Fe small clusters. These Fe-clusters are in superparamagnetic state at room temperature, but they may be ordered below 45 K, as suggested by magnetization data

  16. Use of conventional electrochemical techniques to produce crystalline FeRh alloys induced by Ag seed layer

    Energy Technology Data Exchange (ETDEWEB)

    Noce, R.D., E-mail: rodrnoce@iq.unesp.br [Instituto de Química, Universidade Estadual Paulista, UNESP, 14800-900 Araraquara, SP (Brazil); Benedetti, A.V. [Instituto de Química, Universidade Estadual Paulista, UNESP, 14800-900 Araraquara, SP (Brazil); Passamani, E.C. [Departamento de Física, Universidade Federal do Espírito Santo, 29075-910 Vitória, ES (Brazil); Kumar, H.; Cornejo, D.R. [Instituto de Física, Universidade de São Paulo, USP, 05508-090 São Paulo, SP (Brazil); Magnani, M. [Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), 13083-970 Campinas, SP (Brazil)

    2013-10-05

    Highlights: •Production of FeRh alloys by electrodeposition. •Use of Ag seed layer causes crystallization in electrodeposited Fe{sub 20}Rh{sub 80} alloy. •Mössbauer spectroscopy indicates that the FeRh/Ag alloy has a long range atomic order structure. -- Abstract: By combining galvanic displacement and electrodeposition techniques, an ordered Fe{sub 20}Rh{sub 80} structure deposited onto brass was investigated by X-ray diffractometry, Mössbauer spectroscopy and magnetization measurements. Mössbauer and X-ray diffraction analyses suggest that the Fe–Rh alloy directly electrodeposited onto brass displays a nanocrystalline state while a similar alloy deposited onto Ag/brass shows a faced centered cubic-like structure, with dendrites-like features. These results directly indicate that the presence of Ag seed layer is responsible for the Fe–Rh alloy crystallization process. In addition, room temperature Mössbauer data indicate firstly paramagnetic states for two Fe-species. In the dominant Fe-species (major fraction of the Mössbauer spectra), Fe atoms are situated at a cubic environment and it can be attributed to the γ-Fe{sub 20}Rh{sub 80} alloy based on their hyperfine parameters. In the second species, Fe atoms are placed in a non-local symmetry, which can be related to Fe atoms at the grain boundaries or/and Fe small clusters. These Fe-clusters are in superparamagnetic state at room temperature, but they may be ordered below 45 K, as suggested by magnetization data.

  17. High-energy X-ray diffuse scattering studies on deformation-induced spatially confined martensitic transformations in multifunctional Ti-24Nb-4Zr-8Sn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, J. P.; Wang, Y. D.; Hao, Y. L.; Wang, H. L.; Wang, Y.; Nie, Z. H.; Su, R.; Wang, D.; Ren, Y.; Lu, Z. P.; Wang, J. G.; Hui, X. D.; Yang, R.

    2014-12-01

    Two main explanations exist for the deformation mechanisms in Ti-Nb-based gum metals, i.e. the formation of reversible nanodisturbance and reversible stress-induced martensitic transformation. In this work, we used the in situ synchrotron-based high-energy X-ray diffuse-scattering technique to reveal the existence of a specific deformation mechanism, i.e. deformation-induced spatially confined martensitic transformations, in Ti-24Nb-4Zr-8Sn-0.10O single crystals with cubic 13 parent phase, which explains well some anomalous mechanical properties of the alloy such as low elastic modulus and nonlinear superelasticity. Two kinds of nanosized martensites with different crystal structures were found during uniaxial tensile loading along the [11 0](beta) axis at room temperature and 190 K, respectively. The detailed changes in the martensitic phase transformation characteristics and the transformation kinetics were experimentally observed at different temperatures. The domain switch from non-modulated martensite to a modulated one occurred at 190 K, with its physical origin attributed to the heterogeneity of local phonon softening depending on temperature and inhomogeneous composition in the parent phase. An in-depth understanding of the formation of stress-induced spatially confined nanosized martensites with a large gradient in chemical composition may benefit designs of high-strength and high-ductility alloys. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Fs–ns double-pulse Laser Induced Breakdown Spectroscopy of copper-based-alloys: Generation and elemental analysis of nanoparticles

    International Nuclear Information System (INIS)

    Evolution of nanoparticles ejected during ultra-short (250 fs) laser ablation of certified copper alloys and relative calibration plots of a fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration is presented. All work was performed in air at atmospheric pressure using certified copper-based-alloy samples irradiated by a fs laser beam and followed by a delayed perpendicular ns laser pulse. In order to evaluate possible compositional changes of the fs induced nanoparticles, it was necessary to consider, for all samples used, comparable features of the detected species. With this purpose the induced nanoparticles black-body-like emission evolution and their relative temperature decay have been studied. These data were exploited for defining the distance between the target surface and the successive ns laser beam to be used. The consequent calibration plots of minor constituents (i.e. Sn, Pb and Zn) of the certified copper-based-alloy samples have been reported by taking into account self-absorption effects. The resulting linear regression coefficients suggest that the method used, for monitoring and ruling the fs laser induced nanoparticles, could provide a valuable approach for establishing the occurrence of potential compositional changes of the detected species. All experimental data reveal that the fs laser induced nanoparticles can be used for providing a coherent composition of the starting target. In the meantime, the fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration here used can be considered as an efficient technique for compositional determination of the nanoparticles ejected during ultra-short laser ablation processes. - Highlights: • Laser induced NP continuum black-body-like emission was used for T determination. • Invariable composition of generated NPs was assumed in the range of 20 μs. • Fs-ns DP-LIBS was employed for the compositional characterization of NPs. • NPs obtained by fs

  19. Field-induced-moment nuclear coupling for {sup 59}Co in a Heusler alloy Co{sub 2}TiGa

    Energy Technology Data Exchange (ETDEWEB)

    Furutani, Y; Nishihara, H [Faculty of Science and Technology, Ryukoku University, Otsu 520-2194 (Japan); Kanomata, T [Faculty of Engineering, Tohoku Gakuin University, Tagajo 985-8537 (Japan); Kobayashi, K; Ishida, K [Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Kainuma, R [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Koyama, K; Watanabe, K [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Goto, T, E-mail: nishihara@rins.ryukoku.ac.j [Faculty of Science and Technology, Sophia University, Tokyo 102-8554 (Japan)

    2009-03-01

    The positive hyperfine field at Co nucleus in a Heusler alloy Co{sub 2}TiGa is discussed to be not dominated by the orbital hyperfine field from a quite different point of view from former studies. Field-induced-moment nuclear coupling for {sup 59}Co via spin-orbit interaction on Co atom in Co{sub 2}TiGa is discussed to be small from the observed high-field shift of the NMR of {sup 59}Co in the ferromagnetic state of only +0.83 % in contrast to the case of CoCl{sub 2}.2H{sub 2}O with +29%.

  20. Radiation-induced segregation in diluted NiSi and NiGe alloys. Bestrahlungsinduzierte Segregation in verduennten NiSi- uns NiGe-Legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Weigert, M.

    1987-05-12

    By means of 3 MeV electron radiation the radiation-induced Si or Ge enrichment at point defect sinks of dilute NiSi and NiGe alloys (45-496 atppm) was investigated by the ensueing reduction of the concentration of extra-lattice Si or Ge atoms. The concentration of the detached foreign atoms is analyzed by reciprocal damage rates in the temperature range II. In this process the migrating interstitial atoms which are able to form stable and immobile complexes with the foreign atoms, are used as probes for determining the concentration of detached foreign atoms.

  1. Fabrication of Pd/Pd-Alloy Films by Surfactant Induced Electroless Plating for Hydrogen Separation from Advanced Coal Gasification Processes

    Energy Technology Data Exchange (ETDEWEB)

    Ilias, Shamsuddin; Kumar, Dhananjay

    2012-07-31

    Dense Pd, Pd-Cu and Pd-Ag composite membranes on microporous stainless steel substrate (MPSS) were fabricated by a novel electroless plating (EP) process. In the conventional Pd-EP process, the oxidation-reduction reactions between Pd-complex and hydrazine result in an evolution of NH{sub 3} and N{sub 2} gas bubbles. When adhered to the substrate surface and in the pores, these gas bubbles hinder uniform Pd-film deposition which results in dendrite growth leading to poor film formation. This problem was addressed by introducing cationic surfactant in the electroless plating process known as surfactant induced electroless plating (SIEP). The unique features of this innovation provide control of Pd-deposition rate, and Pd-grain size distribution. The surfactant molecules play an important role in the EP process by tailoring grain size and the process of agglomeration by removing tiny gas bubbles through adsorption at the gas-liquid interface. As a result surfactant can tailor a nanocrystalline Pd, Cu and Ag deposition in the film resulting in reduced membrane film thickness. Also, it produces a uniform, agglomerated film structure. The Pd-Cu and Pd-Ag membranes on MPSS support were fabricated by sequential deposition using SIEP method. The pre- and post-annealing characterizations of these membranes (Pd, Pd-Cu and Pd-Ag on MPSS substrate) were carried out by SEM, EDX, XRD, and AFM studies. The SEM images show significant improvement of the membrane surface morphology, in terms of metal grain structures and grain agglomeration compared to the membranes fabricated by conventional EP process. The SEM images and helium gas-tightness studies indicate that dense and thinner films of Pd, Pd-Cu and Pd-Ag membranes can be produced with shorter deposition time using surfactant. H{sub 2} Flux through the membranes fabricated by SIEP shows large improvement compared to those by CEP with comparable permselectivity. Pd-MPSS composite membrane was subjected to test for long term

  2. Abnormal mechanical property evolution induced by heat treatment for a semi-solid forming hypereutectic Al-Fe base alloy

    Directory of Open Access Journals (Sweden)

    Run-xia Li

    2015-05-01

    Full Text Available In the present study, Al-5.5Fe-4Cu-2Zn-0.4Mg-0.5Mn alloy samples were prepared by electromagnetic stirring and semi-solid forming processing, and then the effects of T6 and T1 heat treatments on the microstructures and mechanical properties of the semi-solid forming samples were investigated. The results indicate that after semi-solid forming, the mechanical properties of the sample improved significantly compared to that of the merely electromagnetically stirred sample. The grains of semi-solid forming alloy became almost fine equiaxed; big long strip-shaped Al3Fe phases became short rod-like morphology and distributed uniformly in the matrix. However, the mechanical properties of the T6-treated semi-solid forming sample decreased significantly instead of increasing and, with solution temperature rising, the tensile strength of the alloy decreased further. The results of EDS show that after high temperature solid-solution treatment, the Cu element in the semi-solid forming alloy sample is mainly concentrated at the boundaries of the Al3Fe phases instead of being dissolved in the matrix. At the same time, the grains of the semi-solid forming sample grew slightly after solid-solution treatment. Therefore, the growth of the grains and the accumulation of Cu element at Al3Fe phase boundaries during solution treatment of the semi-solid forming alloy were the main reasons for the mechanical properties decreasing after T6 treatment. The mechanical properties of the alloy were improved after T1 heat treatment due to aging strengthening phase being precipitated in the matrix.

  3. 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.

  4. 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.

  5. Shock-induced mechanical response and spall fracture behavior of an extra-low interstitial grade Ti–6Al–4V alloy

    International Nuclear Information System (INIS)

    The mechanical response and spall fracture behavior of an extra-low interstitial (ELI) grade Ti–6Al–4V alloy are systemically investigated during one-dimensional shock loading. The effects of oxygen content on the shock response and dynamic failure characteristic of Ti–6Al–4V are also shown through the comparison of the obtained results with those for commercial Ti–6Al–4V. The measured Hugoniot elastic limit (HEL) of Ti–6Al–4V ELI is lower than that of commercial Ti–6Al–4V. While the fitted shock parameters and the measured Hugoniot in the stress-particle velocity space of Ti–6Al–4V ELI are found to be almost identical to those of commercial Ti–6Al–4V. These results indicate that the oxygen content can significantly affect the HEL of Ti–6Al–4V, but has little or no influence on the shock response of this alloy beyond the HEL. The postshock Ti–6Al–4V ELI does not display shock-induced strengthening during quasistatic and dynamic compression tests. Transmission electron microscopy (TEM) analyses reveal that the lack of high density dislocations or dislocation cells limits the shock-induced strengthening effect, although dislocation multiplication and tangles lead to increased yield strength and strain hardening rate of the reloaded material. Finally, Ti–6Al–4V ELI is demonstrated to spall in a ductile manner, and has similar spall strengths to those of commercial Ti–6Al–4V under different shock loading conditions. The oxygen content exerts no effect on the spall fracture manner of Ti–6Al–4V, although reducing the oxygen content enables this alloy to endure more micro-damages

  6. Microstructure Evolution and High-Temperature Compressibility of Modified Two-Step Strain-Induced Melt Activation-Processed Al-Mg-Si Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Chia-Wei Lin

    2016-05-01

    Full Text Available A two-step strain-induced melt activation (TS-SIMA process that omits the cold working step of the traditional strain-induced melt activation (SIMA process is proposed for 6066 Al-Mg-Si alloy to obtain fine, globular, and uniform grains with a short-duration salt bath. The results show that increasing the salt bath temperature and duration leads to a high liquid phase fraction and a high degree of spheroidization. However, an excessive salt bath temperature leads to rapid grain growth and generates melting voids. The initial degree of dynamic recrystallization, which depends on the extrusion ratio, affects the globular grain size. With an increasing extrusion ratio, the dynamic recrystallization becomes more severe and the dynamic recrystallized grain size becomes smaller. It results in the globular grains becomes smaller. The major growth mechanism of globular grains is Ostwald ripening. Furthermore, high-temperature compressibility can be improved by the TS-SIMA process. After a 4 min salt bath at 620 °C, the high-temperature compression ratio become higher than that of a fully annealed alloy. The results show that the proposed TS-SIMA process has great potential.

  7. Hydrogen-induced crack formation in the low-alloy steel 26 NiCrMoV 145 with a yield strength of approx. 850 N/mm/sup 2/

    Energy Technology Data Exchange (ETDEWEB)

    David, W.; Schleithoff, K.; Schmitz, F.

    1986-06-01

    In recent years intergranular stress corrosion cracking has occurred worldwide in the shrink-fitted discs of low-pressure turbine rotors made of low-alloy steels. Both anodic stress corrosion cracking and hydrogen-induced crack formation have been mentioned in the literature as possible failure mechanisms. Clarification of the role of hydrogen induced cracking was sought by carrying out a variety of tests with the low-alloy steel 26NiCrMoV 14 5. The results indicate that hydrogen plays a decisive role in the failure mechanism, provided it is available in sufficiently high quantities.

  8. A model considering mechanical anisotropy of magnetic-field-induced superelastic strain in magnetic shape memory alloys

    International Nuclear Information System (INIS)

    Highlights: ► The model analyzes mechanical anisotropy of magnetic shape memory alloy. ► The numerical evaluation of Eshelby tensor of shape memory alloy is obtained. ► Interaction energy of magnetic shape memory alloy is analyzed. - Abstract: Under applied mechanical load and magnetic field, a micromechanics-based thermodynamic model taking account of mechanical anisotropy of magnetic shape memory alloys (MSMAs) is developed in this work. Considering the crystallographic and magnetic microstructure, the internal state variables are chosen and the model can capture the magnetic shape memory effect caused by the martensitic variant reorientation process. It is assumed that the Gibbs free energy is consisted of the mechanical potential energy of anisotropic matrix, the Zeeman energy and the magnetocrystalline anisotropy energy in the model. In terms of the balance between the thermodynamic driving force derived from the reduction of Gibbs free energy and the resistive force for the variant reorientation, the kinetic equation is established and the Eshelby tensor of anisotropic MSMAs is then obtained by using numerical evaluation. At last, the effects of the anisotropy on interaction energy and macroscopic strain are discussed. The assumption of isotropy tends to underestimate interaction energy and macroscopic strain. The results considering mechanical anisotropy are in good agreement with the experimental data.

  9. A Laser Induced Breakdown Spectroscopy application based on Local Thermodynamic Equilibrium assumption for the elemental analysis of alexandrite gemstone and copper-based alloys

    International Nuclear Information System (INIS)

    Graphical abstract: Self-calibrated analytical techniques based on the approximation of Local Thermodynamic Equilibrium (LTE) have been employed for the analysis of gemstones and copper-based alloys by LIBS (Laser Induced Breakdown Spectroscopy), with a special focus on LTE conditions in laser induced plasmas. Highlights: ► Discussion of Local Thermodynamic Equilibrium (LTE) condition in laser-induced plasmas. ► LIBS enables elemental analysis with self-calibrated LTE-based methods. ► Be detection in alexandrite gemstone is made possible by LIBS. - Abstract: Laser Induced Breakdown Spectroscopy (LIBS) is an appealing technique to study laser-induced plasmas (LIPs), both from the basic diagnostics point of view and for analytical applications. LIPs are complex dynamic systems, expanding at supersonic velocities and undergoing a transition between different plasma regimes. If the Local Thermodynamic Equilibrium (LTE) condition is valid for such plasmas, several analytical methods can be employed and fast quantitative analyses can be performed on a variety of samples. In the present paper, a discussion about LTE is carried out and an innovative application to the analysis of the alexandrite gemstone is presented. In addition, a study about the influence of plasma parameters on the performance of LTE-based methods is reported for bronze and brass targets.

  10. A Laser Induced Breakdown Spectroscopy application based on Local Thermodynamic Equilibrium assumption for the elemental analysis of alexandrite gemstone and copper-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    De Giacomo, A. [Department of Chemistry, University of Bari, Via Orabona 4, 70126 Bari (Italy); Institute of Inorganic Methodologies and Plasmas - CNR, U.O.S. Bari, Via Amendola 122/D, 70126 Bari (Italy); Dell' Aglio, M. [Institute of Inorganic Methodologies and Plasmas - CNR, U.O.S. Bari, Via Amendola 122/D, 70126 Bari (Italy); Gaudiuso, R., E-mail: rosalba.gaudiuso@ba.imip.cnr.it [Institute of Inorganic Methodologies and Plasmas - CNR, U.O.S. Bari, Via Amendola 122/D, 70126 Bari (Italy); Santagata, A. [Institute of Inorganic Methodologies and Plasmas - CNR, U.O.S. Potenza, Via S. Loja, Zona Ind., 85050 Tito Scalo (PZ) (Italy); Senesi, G.S. [Institute of Inorganic Methodologies and Plasmas - CNR, U.O.S. Bari, Via Amendola 122/D, 70126 Bari (Italy); Rossi, M.; Ghiara, M.R. [Department of Earth Sciences, University of Naples ' Federico II' , Via Mezzocannone 8, 80134 Naples (Italy); Capitelli, F. [Institute of Crystallography - CNR, Via Salaria Km 29.300, 00015 Monterotondo (Roma) (Italy); De Pascale, O. [Institute of Inorganic Methodologies and Plasmas - CNR, U.O.S. Bari, Via Amendola 122/D, 70126 Bari (Italy)

    2012-04-04

    Graphical abstract: Self-calibrated analytical techniques based on the approximation of Local Thermodynamic Equilibrium (LTE) have been employed for the analysis of gemstones and copper-based alloys by LIBS (Laser Induced Breakdown Spectroscopy), with a special focus on LTE conditions in laser induced plasmas. Highlights: Black-Right-Pointing-Pointer Discussion of Local Thermodynamic Equilibrium (LTE) condition in laser-induced plasmas. Black-Right-Pointing-Pointer LIBS enables elemental analysis with self-calibrated LTE-based methods. Black-Right-Pointing-Pointer Be detection in alexandrite gemstone is made possible by LIBS. - Abstract: Laser Induced Breakdown Spectroscopy (LIBS) is an appealing technique to study laser-induced plasmas (LIPs), both from the basic diagnostics point of view and for analytical applications. LIPs are complex dynamic systems, expanding at supersonic velocities and undergoing a transition between different plasma regimes. If the Local Thermodynamic Equilibrium (LTE) condition is valid for such plasmas, several analytical methods can be employed and fast quantitative analyses can be performed on a variety of samples. In the present paper, a discussion about LTE is carried out and an innovative application to the analysis of the alexandrite gemstone is presented. In addition, a study about the influence of plasma parameters on the performance of LTE-based methods is reported for bronze and brass targets.

  11. A combined experimental and computational study of the pressure dependence of the vibrational spectrum of solid picene C_22H_14

    OpenAIRE

    Capitani, F.; Hoeppner, M.; Joseph, B; Malavasi, L.; Artioli, G. A.; Baldassarre, L.; Perucchi, A.; Piccinini, M.; Lupi, S.; Dore, P.; Boeri, L.; Postorino, P.

    2013-01-01

    We present high-quality optical data and density functional perturbation theory calculations for the vibrational spectrum of solid picene (C$_{22}$H$_{14}$) under pressure up to 8 GPa. First-principles calculations reproduce with a remarkable accuracy the pressure effects on both frequency and intensities of the phonon peaks experimentally observed . Through a detailed analysis of the phonon eigenvectors, We use the projection on molecular eigenmodes to unambiguously fit the experimental spec...

  12. Environmentally induced fracture of nickel alloys: a comparison of hydrogen and mercury embrittlement with respect to temperature

    International Nuclear Information System (INIS)

    Previous studies have compared electrolytic hydrogen embrittlement (HE) and liquid metal embrittlement (LME) by mercury for numerous nickel alloys. All alloys tested exhibited embrittlement to some degree with HE and LME having similar fractographies. This study examines the effect of temperature on He and LME of Monel 400 over the range -30 and 800C. Slow strain rate tensile tests were conducted at two strain rates, 1.6 x 10-5s-1 and 1.6 x 10-3s-1, and two grain sizes, 35 μm and 250 μm. Behavior of Monel 400 is compared with previously studied nickel alloys. Results showed that intergranular, tranogranular, and microvoid-coalescence fractures can be obtained in both hydrogen and mercury. Fracture mode is governed by strain at fracture. Embrittlement ceases below -200 in both environment, believed due to lack of mobility of adsorbed hydrogen and lack of wetting by mercury. LME is more severe than HE because hydrogen blunts cracks by promoting plasticity. HE ceases at about 800C because excess plasticity promotes crack blunting and inhibits initiation. LME fractures remain brittle to 800C. An incubation period is normally needed for adsorption of the embrittler or for penetration of the crack through the plane stress surface zone. Otherwise ductile failures in mercury often exhibit longitudinal splitting, believed to be due to the combination of high normal stress, low shear stress, and a clean surface. The existence of a temperature window for LME can be explained on the basis of strain activated localized wetting. Results of this study are consistent with a decohesion mechanism producing intergranular fracture; competing with an enhanced dislocation nucleation mechanism producing transgranular fracture. Monel 400 exhibited the range of features observed for other nickel base alloys at appropriate conditions of temperature, strain rate, and grain size

  13. Excess Ni-doping induced enhanced room temperature magneto-functionality in Ni-Mn-Sn based shape memory alloy

    International Nuclear Information System (INIS)

    Present work reports on the observation of large magnetoresistance (∼−30% at 80 kOe) and magnetocaloric effect (∼12 J·kg−1·K−1 for 0–50 kOe) near room temperature (∼290 K) on the Ni-excess ferromagnetic shape memory alloy Ni2.04Mn1.4Sn0.56. The sample can be thought of being derived from the parent Ni2Mn1.4Sn0.6 alloy, where excess Ni was doped at the expense of Sn. Such Ni doping enhances the martensitic transition temperature and for the Ni2.04Mn1.4Sn0.56 it is found to be optimum (288 K). The doped alloy shows enhanced magneto-functional properties as well as reduced saturation magnetization as compared to the undoped counterpart at low temperature. A probable increment of antiferromagnetic correlation between Mn-atoms on Ni substitution can be accounted for the enhanced magneto-functional properties as well as reduction in saturation moment.

  14. Complex magnetism of Mn-based Pnma ternary alloys: Three exchange interactions induced by the position of Mn atoms

    International Nuclear Information System (INIS)

    Density functional theory was used to study the relationship between magnetism and structure of Mn-based Pnma ternary alloys (MMnX). The magnetic states in these alloys largely rely on the value of Mn–Mn–Mn bond angle. There were two apparent critical bond angles being formed among ferromagnetic double exchange, anti-ferromagnetic super-exchange, and ferromagnetic super-exchange. Results indicated that the magnetic exchange interaction showed continuous transition in MMnX. The magnetism of MMnX was found to function on the basis of the relationship between bond angle and magnetic exchange interaction. This work provides a novel way of designing multi-functional materials made of MMnX with pointed magnetic exchange interaction. - Highlights: • A link between the magnetism and Mn–Mn–Mn bond angle was built in MMnX alloys. • It is found that the exchange interaction translates with the bond angle. • Providing a novel avenue of designing multi-functional MMnX materials

  15. Excess Ni-doping induced enhanced room temperature magneto-functionality in Ni-Mn-Sn based shape memory alloy

    Science.gov (United States)

    Pramanick, S.; Chatterjee, S.; Giri, S.; Majumdar, S.

    2014-09-01

    Present work reports on the observation of large magnetoresistance (˜-30% at 80 kOe) and magnetocaloric effect (˜12 J.kg-1.K-1 for 0-50 kOe) near room temperature (˜290 K) on the Ni-excess ferromagnetic shape memory alloy Ni2.04Mn1.4Sn0.56. The sample can be thought of being derived from the parent Ni2Mn1.4Sn0.6 alloy, where excess Ni was doped at the expense of Sn. Such Ni doping enhances the martensitic transition temperature and for the Ni2.04Mn1.4Sn0.56 it is found to be optimum (288 K). The doped alloy shows enhanced magneto-functional properties as well as reduced saturation magnetization as compared to the undoped counterpart at low temperature. A probable increment of antiferromagnetic correlation between Mn-atoms on Ni substitution can be accounted for the enhanced magneto-functional properties as well as reduction in saturation moment.

  16. Excess Ni-doping induced enhanced room temperature magneto-functionality in Ni-Mn-Sn based shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Pramanick, S.; Giri, S.; Majumdar, S., E-mail: sspsm2@iacs.res.in [Department of Solid State Physics, Indian Association for the Cultivation of Science, 2A and B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032 (India); Chatterjee, S. [UGC-DAE Consortium for Scientific Research, Kolkata Centre, Sector III, LB-8, Salt Lake, Kolkata 700 098 (India)

    2014-09-15

    Present work reports on the observation of large magnetoresistance (∼−30% at 80 kOe) and magnetocaloric effect (∼12 J·kg{sup −1}·K{sup −1} for 0–50 kOe) near room temperature (∼290 K) on the Ni-excess ferromagnetic shape memory alloy Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56}. The sample can be thought of being derived from the parent Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} alloy, where excess Ni was doped at the expense of Sn. Such Ni doping enhances the martensitic transition temperature and for the Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56} it is found to be optimum (288 K). The doped alloy shows enhanced magneto-functional properties as well as reduced saturation magnetization as compared to the undoped counterpart at low temperature. A probable increment of antiferromagnetic correlation between Mn-atoms on Ni substitution can be accounted for the enhanced magneto-functional properties as well as reduction in saturation moment.

  17. Crevice corrosion kinetics of nickel alloys bearing chromium and molybdenum

    International Nuclear Information System (INIS)

    Highlights: ► The crevice corrosion resistance of the tested alloys increased with PREN, which is mainly affected by their Mo content. ► Crevice corrosion kinetics was controlled by ohmic drop only in the more dilute chloride solutions. ► Charge transfer control was observed in concentrated chloride solutions. ► A critical ohmic drop was not necessary for crevice corrosion to occur. ► Ohmic drop was a consequence of the crevice corrosion process in certain conditions. - Abstract: The crevice corrosion kinetics of alloys C-22, C-22HS and HYBRID-BC1 was studied in several chloride solutions at 90 °C. The crevice corrosion resistance of the alloys increased with PREN (Pitting Resistance Equivalent Number), which is mainly affected by the Mo content in the alloys. The crevice corrosion kinetics of the three alloys was analyzed at potentials slightly higher than the repassivation potential. Crevice propagation was controlled by ohmic drop in the more dilute chloride solutions, and by charge transfer in the more concentrated chloride solutions. Ohmic drop was not a necessary condition for crevice corrosion to occur.

  18. Microstructure and Wear Behaviour of Laser-Induced Thermite Reaction Al2O3 Ceramic Coatings on Pure Aluminum and AA7075 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    HUANG Kaijin; LIN Xin; XIE Changsheng; T M Yue

    2008-01-01

    Wear-resistant laser-induced thermite reaction Al2O3 ceramic coatings can be fabricated on pure Al and AA7075 aluminum alloy by laser cladding(one-step method)and laser cladding followed by laser re-melting(two-step method)using mixed powders CuO-Al-SiO2 in order to improve the wear properties of aluminum and aluminum alloy,respectively.The microstructure of the coatings was characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The wear resistance of the coatings was evaluated under dry sliding wear test condition at room temperature.Owing to the presence of hard a-Al2O3 and γ-Al2O,3phases,the coatings exhibited excellent wear resistance.In addition,the wear resistance of the coatings fabricated by two-step method is superior to that of the coatings fabricated by one-step method.

  19. The Effect of Applied Stress on Environment-Induced Cracking of Aluminum Alloy 5052-H3 in 0.5 M NaCl Solution

    Directory of Open Access Journals (Sweden)

    Osama M. Alyousif

    2012-01-01

    Full Text Available The environment-induced cracking (EIC of aluminum alloy 5052-H3 was investigated as a function of applied stress and orientation (Longitudinal rolling direction—Transverse: LT and Transverse—Longitudinal rolling direction: TL in 0.5 M sodium chloride solution (NaCl using a constant load method. The applied stress dependence of the three parameters (time to failure; tf, steady-state elongation rate, Iss, and transition time at which a linear increase in elongation starts to deviate, tss obtained from the corrosion elongation curve showed that these relationships were divided into three regions, the stress-dominated region, the EIC- dominated region, and the corrosion-dominated region. Aluminum alloy 5052-H3 with both orientations showed the same EIC behavior. The value of tss/tf in the EIC-dominated region was almost constant with 0.57±0.02 independent of applied stress and orientation. The fracture mode was transgranular for 5052-H3 with both orientations in the EIC-dominated region. The relationships between log Iss and log tf for 5052-H3 in the EIC-dominated region became a good straight line with a slope of −2 independent of orientation.

  20. Nucleation of cracks from shear-induced cavities in an {alpha}/{beta} titanium alloy in fatigue, room-temperature creep and dwell-fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Lefranc, P. [LMPM, UMR CNRS 6617, ENSMA, 86961 Futuroscope, Chasseneuil Cedex (France); LMS, UMR CNRS 7649, Ecole Polytechnique, 91128 Palaiseau Cedex (France); SNECMA Groupe SAFRAN, 77550 Moissy Cramayel (France); Doquet, V. [LMS, UMR CNRS 7649, Ecole Polytechnique, 91128 Palaiseau Cedex (France)], E-mail: doquet@lms.polytechnique.fr; Gerland, M.; Sarrazin-Baudoux, C. [LMPM, UMR CNRS 6617, ENSMA, 86961 Futuroscope, Chasseneuil Cedex (France)

    2008-10-15

    In titanium alloys, dwell periods during room-temperature stress-controlled fatigue tests are responsible for substantial reductions in lifetime compared to pure fatigue loading. The mechanisms of such a creep-fatigue interaction have been investigated for alloy Ti-6242. Scanning and transmission electron microscopy observations revealed crack initiation by coalescence of shear-induced cavities nucleated at {alpha}/{beta} interfaces in large colonies of {alpha} laths nearly parallel to the loading axis. The density and average size of cavities were larger in dwell-fatigue and creep than in fatigue. A qualitative micromechanical model of cavity nucleation based on discrete dislocation dynamics was developed. The number of cycles for cavity nucleation was computed as a function of the applied stress range. A finite threshold, dependent on the size of {alpha} laths colonies with similar orientation, was found. The simulations predict earlier cavity nucleation in creep or dwell-fatigue than in pure fatigue, which is consistent with the performed experiments.

  1. First-principles calculations of bismuth induced changes in the band structure of dilute Ga-V-Bi and In-V-Bi alloys: chemical trends versus experimental data

    Science.gov (United States)

    Polak, M. P.; Scharoch, P.; Kudrawiec, R.

    2015-09-01

    Bi-induced changes in the band structure of Ga-V-Bi and In-V-Bi alloys are calculated within the density functional theory (DFT) for alloys with Bi ≤3.7% and the observed chemical trends are discussed in the context of the virtual crystal approximation (VCA) and the valence band anticrossing (VBAC) model. It is clearly shown that the incorporation of Bi atoms into III-V host modifies both the conduction band (CB) and the valence band (VB). The obtained shifts of bands in GaP1-xBix, GaAs1-xBix, GaSb1-xBix, InP1-xBix, InAs1-xBix, and InSb1-xBix are respectively, 15, -29, -16, -27, -15, and -10 meV/%Bi for CB, 82, 62, 16, 79, 45, and 16 meV/%Bi for VB, and -17, -3, -2, -8, -6, and 14 meV/%Bi for spin-orbit split off band. The Bi-induced reduction of the band gap is very consistent with the available experimental data. The chemical trends observed in our calculations as well as in experimental data are very clear: in a sequence of alloys from III-P-Bi to III-Sb-Bi the Bi-induced changes in the band structure weaken. For dilute GaSb1-xBix and InSb1-xBix alloys the band structure modification, in the first approximation, can be described within the VCA, while for Ga-V-Bi and In-V-Bi alloys with V = As or P another phenomenological approach is needed to predict the Bi-induced changes in their band structure. We have found that a combination of the VCA with the VBAC model, which is widely applied for highly mismatched alloys, is suitable for this purpose. The chemical trends for III-V-Bi alloys observed in our DFT calculations are also exhibited by the coupling parameter {C}BiM, which describes the magnitude of interaction between Bi-induced levels and VB states in the VBAC model. This coupling parameter monotonously decreases along the sequence of alloys from III-P-Bi to III-Sb-Bi.

  2. Crevice corrosion resistance of Ni-Cr-Mo alloys as engineered barriers in nuclear waste repositories

    International Nuclear Information System (INIS)

    The crevice corrosion re passivation potential was determined by the Potentiodynamic- Galvanostatic-Potentiodynamic (PD-GS-PD) method. Alloys 625, C-22, C-22HS and HYBRID-BC1 were used. Specimens contained 24 artificially creviced spots formed by a ceramic washer (crevice former) wrapped with a PTFE tape. Crevice corrosion tests were performed in 0,1 mol/L and 1 mol/L NaCl solutions at temperatures between 20 and 90ºC, and CaCl2 5 mol/L solution at temperatures between 20 and 117°C. The crevice corrosion resistance of the alloys increased in the following order: 625 < C-22 < C-22HS < HYBRID-BC1. The repassivation potential (ECO) showed the following relationship with temperature (T) and chloride concentration ([Cl-]) ECO = (A + B T) log [Cl-] + C T + D; where A, B, C and D are constants. At temperatures above 90°C, ECO for alloy 625 stabilized at a minimum value of -0.26 VSCE (author)

  3. Electron-beam-induced structure transformation of the quasicrystalline phases of the Al62Cu20Co15Si3 alloy

    International Nuclear Information System (INIS)

    Some details on the phase transformation experienced by the quasicrystalline phases of the Al62Cu20Co15Si3 alloy under a 400 kV electron beam are given. The transition is observed in situ with a high resolution electron microscope and recorded on video tape. The results show that the electron beam radiation produces a sequence of changes similar to the ones observed in an ion-beam-induced amorphization process. Considering electron radiation damage analysis, the results agree well with the ''flip-flop'' model [Coddens, Bellisent, Calvayrac and Ambroise (1991) Europhys. Lett. 16, 2712] where the transition from a quasicrystalline phase to a crystalline phase is produced by atomic displacements but not in a cascade way. (author)

  4. Study of the fabrication and thermally induced transformation of amorphous Mg50Ni50 obtained by mechanical alloying

    International Nuclear Information System (INIS)

    This work studied the amorphization process by mechanical alloying of a Mg50Ni50 alloy and its later thermal transformation into stable equilibrium phases. The amorphous alloy was produced using a SPEX 8000D mill, under controlled Ar atmosphere, with a ratio in ball mass: material of 20:1, from powders of Ni and cuttings of Mg. The evolution of the phases during the amorphization process was qualitatively determined by X-ray diffraction. The results showed that a noticeable microstructural refinement of the Mg and Ni occurs at the start of the milling, and that this accumulation of defects amorphitizes part of the system, producing an amorphous precursor, which mechanically crystallizes the Mg2Ni. As the milling time increases and more energy is added to the system, the structure of the Mg2Ni collapses giving way to the appearance of the amorphous Mg50Ni50 phase. With reference to the thermal transformation of the amorphous solid to the stable equilibrium phases, the joint results obtained by differential scanning calorimetry and X-ray diffraction, indicate that this occurs in two stages: at temperatures close to 350oC the amorphous Mg50Ni50 transforms into a mixture of phases, composed of Mg2Ni and a residual amorphous, which at temperatures close to 450oC undergoes the transformation into MgNi2. A temperature-heating rate-transformation (T-HR-T) diagram was built for the passage of the amorphous Mg50Ni50 into Mg2Ni and MgNi2 using the calorimetric data (au)

  5. Physics-based simulation modeling and optimization of microstructural changes induced by machining and selective laser melting processes in titanium and nickel based alloys

    Science.gov (United States)

    Arisoy, Yigit Muzaffer

    Manufacturing processes may significantly affect the quality of resultant surfaces and structural integrity of the metal end products. Controlling manufacturing process induced changes to the product's surface integrity may improve the fatigue life and overall reliability of the end product. The goal of this study is to model the phenomena that result in microstructural alterations and improve the surface integrity of the manufactured parts by utilizing physics-based process simulations and other computational methods. Two different (both conventional and advanced) manufacturing processes; i.e. machining of Titanium and Nickel-based alloys and selective laser melting of Nickel-based powder alloys are studied. 3D Finite Element (FE) process simulations are developed and experimental data that validates these process simulation models are generated to compare against predictions. Computational process modeling and optimization have been performed for machining induced microstructure that includes; i) predicting recrystallization and grain size using FE simulations and the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, ii) predicting microhardness using non-linear regression models and the Random Forests method, and iii) multi-objective machining optimization for minimizing microstructural changes. Experimental analysis and computational process modeling of selective laser melting have been also conducted including; i) microstructural analysis of grain sizes and growth directions using SEM imaging and machine learning algorithms, ii) analysis of thermal imaging for spattering, heating/cooling rates and meltpool size, iii) predicting thermal field, meltpool size, and growth directions via thermal gradients using 3D FE simulations, iv) predicting localized solidification using the Phase Field method. These computational process models and predictive models, once utilized by industry to optimize process parameters, have the ultimate potential to improve performance of

  6. Grain size effect on the structural parameters of the stress induced epsilonhcp: martensite in iron-based shape memory alloy

    Directory of Open Access Journals (Sweden)

    Fabiana Cristina Nascimento

    2008-03-01

    Full Text Available The aim of this work was to study the effect of austenitic grain size (GS reduction on the structural parameters of the epsilonhcp - martensite in stainless shape memory alloy (SMA. Rietveld refinement data showed an expansion in c-axis and a reduction in a and b-axis with thermo-mechanical cycles for all samples analyzed. Samples with 75 < GS (µm < 129 were analyzed. It was also observed an increase of the unit cell volume in this phase with GS reduction. The smallest grain size sample (GS = 75 µm presented a c/a ratio of 1.649, and approximately 90% of total shape memory recovery.

  7. Microstructural evolution during isothermal aging and strain-induced transformation followed by isothermal aging in Co-Cr-Mo-C alloy: A comparative study

    International Nuclear Information System (INIS)

    The present study was undertaken to investigate the effects of isothermal aging (at 850 deg. C for 4, 8, 16 and 24 h) and strain-induced transformation (engineering strains of 10% and 20%) followed by isothermal aging (at 850 deg. C for 4, 8 and 16 h) on the microstructural evolution of a Co-28Cr-5Mo-0.3C alloy. The obtained results showed that isothermal aging at 850 deg. C resulted in the formation of lamellar-type carbides at the grain boundaries. Moreover, X-ray diffraction analysis indicated that isothermal aging of solution treated specimens at 850 deg. C for 24 h did not lead to complete fcc phase transformation to hcp one. In contrast with the isothermally aged specimens, applying plastic deformation to the solutionized samples accelerated the completion and saturation of fcc(metastable) → hcp transformation after 8 h aging at 850 deg. C. In addition, the X-ray diffraction results indicated that implementing isothermal aging of the strain-induced specimens at the higher aging time (16 h) caused the formation of (1 1 1)fcc and (2 0 0)fcc diffraction peaks again. Also, the strain-induced specimens followed by isothermal aging showed higher amount of microhardness as compared with the other specimens aged solely.

  8. High field alloy, thermoelectric, and mm wave studies of the field induced superconducting state in {lambda}-(BETS){sub 2}Fe{sub x}Ga{sub 1-x}Cl{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, J.S.; Choi, E.S.; Rutel, I.B. [Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab; Uji, S. [National Institute for Materials Science, Tsukuba (Japan); Kobayashi, H. [Institute for Molecular Science, Okazaki (Japan); Kobayashi, A. [Tokyo Univ., Bunkyio-ku (Japan). Research Centre for Spectrochemistry; Tanaka, H. [Advanced Industrial Science and Technology (AIST), Tsukuba (Japan). Nanotechnology Research Institute; Tokumoto, M. [Japan Science and Technology Corp (JSTC), Kawaguchi (Japan). Core Research for Evolutional Science and Technology (CREST)

    2003-12-01

    Alloy studies in the {pi} - d organic conductor {lambda}-(BETS){sub 2}Fe{sub x}Ga{sub 1-x}Cl{sub 4} have given new insight into the nature of field induced superconductivity (FISC), since the mechanism of the FISC involves cancellation of the {pi} - d exchange field by the external field. Alloying on the Fe{sub x}Ga{sub 1-x} site allows tuning of the exchange field, thereby influencing the FISC phase boundary. A brief review of the low temperature phases are given, and new high magnetic field thermoelectric and mm wave results that probe the low temperature ground state are presented. (author)

  9. Loose Plant Architecture1 (LPA1) determines lamina joint bending by suppressing auxin signalling that interacts with C-22-hydroxylated and 6-deoxo brassinosteroids in rice

    Science.gov (United States)

    Liu, Jing Miao; Park, Soon Ju; Huang, Jin; Lee, Eun Jin; Xuan, Yuan Hu; Je, Byoung Il; Kumar, Vikranth; Priatama, Ryza A.; Raj K, Vimal; Kim, Sung Hoon; Min, Myung Ki; Cho, Jun Hyeon; Kim, Tae Ho; Chandran, Anil Kumar Nalini; Jung, Ki Hong; Takatsuto, Suguru; Fujioka, Shozo; Han, Chang-deok

    2016-01-01

    Lamina inclination is a key agronomical character that determines plant architecture and is sensitive to auxin and brassinosteroids (BRs). Loose Plant Architecture1 (LPA1) in rice (Oryza sativa) and its Arabidopsis homologues (SGR5/AtIDD15) have been reported to control plant architecture and auxin homeostasis. This study explores the role of LPA1 in determining lamina inclination in rice. LPA1 acts as a positive regulator to suppress lamina bending. Genetic and biochemical data indicate that LPA1 suppresses the auxin signalling that interacts with C-22-hydroxylated and 6-deoxo BRs, which regulates lamina inclination independently of OsBRI1. Mutant lpa1 plants are hypersensitive to indole-3-acetic acid (IAA) during the lamina inclination response, which is suppressed by the brassinazole (Brz) inhibitor of C-22 hydroxylase involved in BR synthesis. A strong synergic effect is detected between lpa1 and d2 (the defective mutant for catalysis of C-23-hydroxylated BRs) during IAA-mediated lamina inclination. No significant interaction between LPA1 and OsBRI1 was identified. The lpa1 mutant is sensitive to C-22-hydroxylated and 6-deoxo BRs in the d61-1 (rice BRI1 mutant) background. We present evidence verifying that two independent pathways function via either BRs or BRI1 to determine IAA-mediated lamina inclination in rice. RNA sequencing analysis and qRT-PCR indicate that LPA1 influences the expression of three OsPIN genes (OsPIN1a, OsPIN1c and OsPIN3a), which suggests that auxin flux might be an important factor in LPA1-mediated lamina inclination in rice. PMID:26826218

  10. Effect of hardening induced by cold expansion on damage fatigue accumulation and life assessment of Aluminum alloy 6082 T6

    Directory of Open Access Journals (Sweden)

    Bendouba Mostefa

    2012-12-01

    Full Text Available Hole cold expansion (HCE is an effective method to extend the fatigue life of mechanical structures. During cold expansion process compressive residual stresses around the expanded hole are generated. The enhancement of fatigue life and the crack initiation and growth behavior of a holed specimen were investigated by using the 6082 Aluminum alloy. The present study suggests a simple technical method for enhancement of fatigue life by a cold expansion hole of pre-cracked specimen. Fatigue damage accumulation of cold expanded hole in aluminum alloy which is widely used in transportation and in aeronautics was analyzed. Experimental tests were carried out using pre-cracked SENT specimens. Tests were performed in two and four block loading under constant amplitude. These tests were performed by using two and four blocks under uniaxial constant amplitude loading. The increasing and decreasing loading were carried. The experimental results were compared to the damage calculated by the Miner's rule and a new simple fatigue damage indicator. This comparison shows that the 'damaged stress model', which takes into account the loading history, yields a good estimation according to the experimental results. Moreover, the error is minimized in comparison to the Miner's model.

  11. Localized corrosion resistance of high nickel alloys as candidate materials for nuclear waste repository. Effect of alloy and weldment aging at 427 C for up to 40,000 h

    International Nuclear Information System (INIS)

    Ni-Cr-Mo alloys (e.g. C-22, C-4 and C-276) are considered candidate materials for nuclear waste containers because they offer excellent resistance to localized attack in conditions that can be encountered at the permanent repository site. Electrochemical and standard immersion tests showed that the most resistant of the studied alloys to localized attack was C-22 alloy and the less resistant was C-4 alloy. It was important to determine if long time exposure to low temperatures (below 500 C) would be detrimental in the resistance of these alloys to localized attack (pitting and crevice corrosion). After aging for 40,000 h at 427 C none of these alloys showed precipitation of a second phase (such as carbides or μ phase) that could promote a higher corrosion susceptibility of the alloys. Moreover, immersion and electrochemical tests showed that, after the same long term aging, the susceptibility to corrosion of both the base material and weldments remained unchanged. The effects of alloying elements on the resistance of the alloys to localized attack is discussed

  12. Simulation of thermos-solutal convection induced macrosegregation in a Sn-10%Pb alloy benchmark during columnar solidification

    Science.gov (United States)

    Zheng, Y.; Wu, M.; Kharicha, A.; Ludwig, A.

    2016-03-01

    In order to investigate the effect of thermo-solutal convection on the formation of macrosegregation during columnar solidification, simulations with a liquid-columnar two phase model were carried out on a 2D rectangular benchmark of Sn-10%Pb alloy. The solidification direction in the benchmark is unidirectional: (') downwards from top to bottom or (2) upwards from bottom to top. Thermal expansion coefficient, solutal expansion coefficient and liquid diffusion coefficient of the melt are found to be key factors influencing the final macrosegregation. The segregation range and distribution are also strongly influenced by the benchmark configurations, e.g. the solidifying direction (upwards or downwards) and boundary conditions, et al. The global macrosegregation range increases with the velocity magnitude of the melt during the process of solidification.

  13. EXAFS study on solute precipitation in FeCu alloy induced by energetic electron bombardments and thermal aging

    International Nuclear Information System (INIS)

    The extended X-ray absorption fine structure (EXAFS) measurement is a useful tool for the observation of local atomic arrangements around selected atoms. We performed EXAFS measurements for the electron-irradiated and the thermally-aged Fe–0.6 wt.% Cu alloy and compared the experimental result with that of the simulation by the FEFF simulation code in order to investigate the local atomic structure around Cu atoms. Cu precipitates which were produced by the thermal aging at 773 K transformed from the bcc structure to the fcc structure as the precipitates grow large enough. However, for electron-irradiated specimens, although the hardness greatly increased, the transformation of Cu precipitates from the bcc to the fcc structure was not clearly confirmed. This result indicates that small sized Cu precipitates which had the bcc structure were produced by the electron irradiation and they could hardly coarsen during the irradiation

  14. Evidence for the enhancement of stress induced ordering in a Ag27 at.% Zn alloy due to electron irradiation

    International Nuclear Information System (INIS)

    Damping studies of the Zener relaxation in an Ag.27 at.% Zn alloy have been conducted by use of an inverted torsion pendulum working in line with a 2 MeV accelerator. The internal friction spectrum traced during bombardment in a flux of 1.5.10sup13e-/cm2s, in the temperature range 50 to 250degC (0.3-0.5Tsub(m)), indicates an increase in the rate of the Zener relaxation relative to that of nonirradiated specimens. The excess concentration of point defects associated with this enhanced relaxation rate is discussed within the frame of the models which describe the steady state defect supersaturation existing under flux

  15. Kinetic arrest induced antiferromagnetic order in hexagonal FeMnP0.75Si0.25 alloy

    International Nuclear Information System (INIS)

    The magnetic state of the FeMnP0.75Si0.25 alloy was investigated by first principles calculations. The coexistence of ferromagnetic and antiferromagnetic phases in FeMnP0.75Si0.25 with the same hexagonal crystal structure was revealed. It was found that kinetic arrest during the transition from the high temperature disordered paramagnetic phase to the low temperature ordered ferromagnetic phase results in the intermediate metastable and partially disordered antiferromagnetic phase. We propose that the ratio of the ferromagnetic and antiferromagnetic phases in the FeMnP0.75Si0.25 sample can be tuned by adjusting the kinetic process of atomic diffusion. The investigations suggest that careful control of the kinetic diffusion process provides another tuning parameter to design candidate magnetocaloric materials

  16. On the porosity induced by externally solidified crystals in high-pressure die-cast of AM60B alloy and its effect on crack initiation and propagation

    International Nuclear Information System (INIS)

    The porosity induced by the externally solidified crystals (ESCs) in high pressure die casting of AM60B magnesium alloy was investigated. Attention was focused on the formation of the porosity due to the presence of ESCs and its effect on the crack initiation and propagation during tensile deformation. Based on experimental observations using optical microscopy, scanning electron microscopy and the 3-D high resolution X-ray tomography, it was found that the porosity induced by ESCs could be categorized into two types. The first type of porosity was relatively small in size, globular in geometry and dispersed inside the microstructure, whereas the second type was larger in size with an interconnected structure. During the in situ observation of tensile deformation, significant crack could be observed at grain boundaries where the second type of porosity was present. The crack propagated by connecting the neighboring porosities towards a direction perpendicular to the tensile stress. The interdendritic shrinkage during solidification at the ESC boundaries was shown to be the primary reason for the formation of the second type of porosity

  17. Stress-induced martensitic transformation in nanometric NiTi shape memory alloy strips: An in situ TEM study of the thickness/size effect

    International Nuclear Information System (INIS)

    Highlights: •An in situ deformation technique in TEM was designed. •The martensitic transformation shows strong size effect. •The size effect is attributed to the effect of damaged surfaces. •The “size effect” is not an intrinsic but of extrinsic influences. -- Abstract: Ultrathin NiTi miniature strips of 40–83 nm in thickness were fabricated by means of focused ion beam milling from a polycrystalline NiTi shape memory alloy. The NiTi strips were subjected to tensile deformation inside a transmission electron microscope using a self-designed tension apparatus for in situ examination of the effect of thickness on the stress induced martensitic transformation behavior in the strips. The study revealed that the transformation was completely suppressed in a strip of 40 nm in thickness whereas it was possible in thicker strips. In these strips, the stress induced martensitic transformation was found to commence sequentially in thicker strips first and then in thinner strips at higher strain (stress) levels, demonstrating the size effect. This size effect is attributed to the effect of damaged surfaces, including a Ga+-impregnated amorphous layer on one side of the strip caused by sample fabrication using FIB and oxidation affected layers on both sides. This means that the observed “size effect” is not an intrinsic behavior of the martensitic transformation in NiTi but of extrinsic influences

  18. Calibration-free analysis of immersed brass alloys using long-ns-duration pulse laser-induced breakdown spectroscopy with and without correction for nonstoichiometric ablation

    International Nuclear Information System (INIS)

    Long-ns-duration, single pulse laser-induced breakdown spectroscopy (LIBS) is known to be an effective method to observe well resolved spectra from samples immersed in water at high hydrostatic pressures. The aim of this study is to investigate whether the signals obtained using this method are suitable for quantitative analysis of chemical composition. Six certified brass alloys consisting of copper (Cu), zinc (Zn) and lead (Pb) were measured underwater using a laser pulse of duration 250 ns, and their compositions were determined using calibration-free LIBS (CF-LIBS) and corrected CF-LIBS (CCF-LIBS) methods. The mass fractions of Cu and Zn calculated using CF-LIBS showed better agreement with the certified values than those determined using CCF-LIBS, with relative errors of Cu 4.2 ± 3.3 % and Zn 7.2 ± 6.4 %. From the results, it can be said that the difference of preferential evaporation and ablation among elements does not need to be considered for underwater measurements with the long-pulse LIBS setup used in this work. While the results indicate that the CF-LIBS method can be applied for in situ quantitative analysis of major elements with concentrations > ~ 10 %, the mass fractions determined for Pb, with concentrations < 5 % had large relative errors, suggesting that an alternative method is required to quantify minor elements. - Highlights: • The spectra of submerged metal alloys obtained using a long pulse is suitable for CF-LIBS. • CF-LIBS determines the mass fractions of major elements of submerged brass targets in water. • The compositions of Cu and Zn are determined within 10 % relative error. • The preferential evaporation and ablation among elements do not have a significant influence on the quantitative analysis of brass samples submerged in water using a long-ns-duration laser pulse

  19. Calibration-free analysis of immersed brass alloys using long-ns-duration pulse laser-induced breakdown spectroscopy with and without correction for nonstoichiometric ablation

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Tomoko, E-mail: takahas@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Thornton, Blair [Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Ohki, Koichi [OK Lab. Co., Ltd. 8-7-3 Shimorenjyaku, Mitaka, Tokyo 181-0013 (Japan); Sakka, Tetsuo [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2015-09-01

    Long-ns-duration, single pulse laser-induced breakdown spectroscopy (LIBS) is known to be an effective method to observe well resolved spectra from samples immersed in water at high hydrostatic pressures. The aim of this study is to investigate whether the signals obtained using this method are suitable for quantitative analysis of chemical composition. Six certified brass alloys consisting of copper (Cu), zinc (Zn) and lead (Pb) were measured underwater using a laser pulse of duration 250 ns, and their compositions were determined using calibration-free LIBS (CF-LIBS) and corrected CF-LIBS (CCF-LIBS) methods. The mass fractions of Cu and Zn calculated using CF-LIBS showed better agreement with the certified values than those determined using CCF-LIBS, with relative errors of Cu 4.2 ± 3.3 % and Zn 7.2 ± 6.4 %. From the results, it can be said that the difference of preferential evaporation and ablation among elements does not need to be considered for underwater measurements with the long-pulse LIBS setup used in this work. While the results indicate that the CF-LIBS method can be applied for in situ quantitative analysis of major elements with concentrations > ~ 10 %, the mass fractions determined for Pb, with concentrations < 5 % had large relative errors, suggesting that an alternative method is required to quantify minor elements. - Highlights: • The spectra of submerged metal alloys obtained using a long pulse is suitable for CF-LIBS. • CF-LIBS determines the mass fractions of major elements of submerged brass targets in water. • The compositions of Cu and Zn are determined within 10 % relative error. • The preferential evaporation and ablation among elements do not have a significant influence on the quantitative analysis of brass samples submerged in water using a long-ns-duration laser pulse.

  20. Co-Cr-Mo Alloy Particles Induce Tumor Necrosis Factor Alpha Production in MLO-Y4 Osteocytes: A Role for Osteocytes in Particle Induced Inflammation

    OpenAIRE

    Kanaji, Arihiko; Caicedo, Marco S.; Virdi, Amarjit S.; Sumner, D. Rick; Hallab, Nadim J.; Sena, Kotaro

    2009-01-01

    Wear debris-induced osteolysis is purportedly the limiting problem affecting the long term results of joint arthroplasty. Pathogenic effects of wear debris in peri-implant cells such as macrophages, osteoblasts and osteoclasts have been well studied. In contrast, the affects of wear-debris on osteocytes, which make up over 90% of all bone cells, remains unknown. We hypothesized that metal implant debris can induce the proinflammatory response in osteocytes. This study demonstrated the effects...

  1. Deformation-induced dissolution and growth of precipitates in an Al–Mg–Er alloy during high-cycle fatigue

    International Nuclear Information System (INIS)

    The dissolution and growth of Al3(Er, Zr) precipitates during tensile fatigue experiments were investigated by quasi-in situ and post-mortem scanning transmission electron microscopy with Z contrast imaging and X-ray energy dispersive spectroscopy. Al3(Er, Zr) particles were observed with both non-core–shell and core–shell structures, which were formed during multiple-stage precipitations, in an Al–Mg–Er alloy. After fatigue deformations, the average size of the non-core–shell structured precipitates increased significantly. By tracing the same precipitate particles before and after a high-cycle fatigue test, quasi-in situ electron microscopy revealed that the increase of average particle size is associated with the substantial dissolution of small non-core–shell structured Al3(Er, Zr) particles, whose diameters are generally less than 15 nm, and a consequent growth of larger non-core–shell Al3(Er, Zr) precipitates. On the contrary, the core–shell structured Al3(Er, Zr) precipitates remain stable during high-cycle fatigue tests. Possible mechanisms for the dissolution and growth of non-core–shell structured Al3(Er, Zr) precipitates are discussed in terms of particle size, interfacial energy and lattice mismatch, in comparison to the stable core–shell structured precipitates

  2. Mechanistic understanding of irradiation-induced corrosion of zirconium alloys in nuclear power plants: Stimuli, status, and outlook

    International Nuclear Information System (INIS)

    Failures in the basic materials used in nuclear power plants continue to be costly and insidious, despite increasing industry vigilance to catch failures before they degrade safety. For instance, the overall costs to the US industry from materials problems could amount to as much as $10 billion annually. Moreover, estimates indicate that the cost of a pipe failure in a nuclear plant is one hundred times greater than the cost of a similar failure in a coal-fired plant. There are important practical stimuli and much scope for further understanding of the effects of irradiation on Zr-alloys (and other materials used in nuclear installations) by careful experimentation. Moreover, these studies need to address the effect of irradiation on all components of heterogeneous systems: the metal, the oxide and the environment, and especially those processes recurring at the interphases between these components. The present paper is aimed at providing specialists with some systematic information on the subject and with important considerations on the key items for further experimentation

  3. Laser-induced spallation of aluminum and Al alloys at strain rates above 2x106 s-1

    International Nuclear Information System (INIS)

    Material microstructure is a significant determinant of the tensile stress at which materials fail. Using a high-energy laser to drive shocks in thin slabs, we have explored the role material microstructure plays on the spall strength of high-purity and alloyed aluminum at strain rates of (2-7.5)x106 s-1. Slabs of pure recrystallized Al and recrystallized or cold worked Al+3 wt % Mg were shock driven using the Z-Beamlet Laser at Sandia National Laboratories. Velocity interferometer measurements determined the spall strength of the materials, and postshot target analysis explored the microscopic fracture morphology. We observed the greatest spall strength for large-grained, recrystallized high-purity aluminum, with the dominant failure mode being ductile and transgranular. We observe for the first time at these strain rates fracture features for a fine-grained Al+3 wt % Mg that were a combination of brittle intergranular and ductile transgranular fracture types. Postshot analysis of target cross sections and hydrocode simulations indicate that this mixed-mode failure results from spall dynamics occurring on spatial scales on the order of the grain size. Differences in spall strength between these Al samples were experimentally significant and correlate with the damage morphologies observed

  4. Phase transformation in Ni-Mn-Sn ferromagnetic shape memory alloy thin films induced by dense ionization

    Energy Technology Data Exchange (ETDEWEB)

    Vishnoi, R.; Kaur, D. [Indian Institute of Technology Roorkee, Functional Nanomaterials Research Laboratory, Department of Physics and Centre of Nanotechnology, Roorkee (India); Singhal, R.; Asokan, K.; Kanjilal, D. [Aruna Asaf Ali Marg, Inter University Accelerator Centre, New Delhi (India)

    2012-06-15

    The effects of 200 MeV Au ions irradiation on the structural and magnetic properties of Ni-Mn-Sn ferromagnetic shape memory alloy (FSMA) thin films have been systematically investigated. In order to understand the role of initial microstructure and phase of the film with respect to high energy irradiation, the two types of Ni-Mn-Sn FSMA films having different phases at room temperature were irradiated, one in martensite phase (Ni{sub 58.9}Mn{sub 28.0}Sn{sub 13.1}) and other in austenite phase (Ni{sub 50}Mn{sub 35.6}Sn{sub 14.4}). Transmission electron microscope (TEM) and scanning electron microscope (SEM) images along with the diffraction patterns of X-rays and electrons confirm that martensite phase transforms to austenite phase at a fluence of 6 x 10{sup 12} ions/cm{sup 2} and a complete amorphization occurs at a fluence of 3 x 10{sup 13} ions/cm{sup 2}, whereas ion irradiation has a minimal effect on the austenitic structure (Ni{sub 50}Mn{sub 35.6}Sn{sub 14.4}). Thermo-magnetic measurements also support the above mentioned behaviour of Ni-Mn-Sn FSMA films with increasing fluence of 200 MeV Au ions. The results are explained on the basis of thermal spike model considering the core and halo regions of ion tracks in FSMA materials. (orig.)

  5. Pastern recognition of clusters formed in 4.1(4.5)A GeV/c 22Ne(28Si) interaction with emulsion using Lobachevsky velocity space

    International Nuclear Information System (INIS)

    The experimental data of 4.1(4.5)A GeV/c 22Ne(28Si) emulsion interactions, which has been measured in the laboratory of high energy physics ( LHEP ) at Cairo University , has been utilized in this analysis. In the present paper we propose the use of Bubelev's graphical method to visualize the candidates of cluster formation in nucleus - nucleus interactions. This method is based on the Chernikov geometry formulation of relativistic kinematics in patterns in the Lobachevsky velocity space in which the motion of particles are equivalent to the Lorentz group. The analysis has shown that events which are identified as formation of clusters in 22Ne(28Si) emulsion interactions are well illustrated in the Lobachevsky velocity space using the principle of likeness (closeness). The study will be extended to include other reactions and other types of particles

  6. STRAIN INDUCED TRANSFORMATIONS AND PLASTICITY IN TRANSAGE Ti-11.6V-2Al-2Sn-6Zr (Tl134) AND Ti-11.5V - 2Al-2Sn-11.3Zr (Tl29) ALLOYS

    OpenAIRE

    Nwobu, A.; Flower, H.; West, D

    1982-01-01

    An investigation is reported on two β quenched titanium Transage alloys, namely (i) T 134 which contains only orthorhombic α" martensite and (ii) T 129 which contains mainly retained β and a small amount of α" after quenching from the β phase. Strain induced shear, transformations of β to α" and the α" to hexagonal α' take place in the temperature range 77-373K and are associated with enhanced ductility.

  7. 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...... thermoelastic coefficients and age hardenable low expansion alloys....

  8. Underwater Superoleophobicity Induced by the Thickness of the Thermally Grown Porous Oxide Layer on C84400 Copper Alloy

    Directory of Open Access Journals (Sweden)

    Aniedi Nyong

    2014-02-01

    Full Text Available The underwater contact angle behavior on oxide layers of varying thicknesses was studied. These oxide layers were grown by thermally oxidizing C84400 copper alloys in N2-0.75 wt.% O2 and N2-5 wt.% O2 gas mixtures at 650 °C. Characterization of the oxidized specimens was effected using X-ray diffraction, scanning electron microscope (SEM and contact angle goniometer. The results from the X-ray diffraction analyses confirmed the formation of CuO, ZnO and PbO. The average sizes of the oxide granules were in the range of 70 nm to 750 nm, with the average thickness of the oxide layer increasing with the increase in the weight percent of oxygen in the N2-O2 gas mixtures. The results showed that the oxide layer growth followed the parabolic law. The underwater oil contact angles increased, due to the change in the surface morphology and porosity of the oxide layer. The small sizes and irregular packing of the oxide granules cause hierarchical rough surface layers with pores. The estimated pore sizes, in the range of 88 ± 40 to 280 ± 76, were predominant on the oxide layers of the samples processed in the N2-5 wt.% O2 gas mixture. The presence of these pores caused an increase in the porosities as the thickness of the oxide layers increased. At oxide layer thickness above 25 microns, the measured contact angle exceeded 150° as underwater superoleophobicity was recorded.

  9. Study of the Induced Anisotropy in Field Annealed Hitperm Alloys by Mössbauer Spectroscopy and Kerr Microscopy

    Science.gov (United States)

    Blázquez, J. S.; Marcin, J.; Andrejka, F.; Franco, V.; Conde, A.; Skorvanek, I.

    2016-08-01

    Samples of Fe39Co39Nb6B15Cu1 alloy were nanocrystallized under zero field annealing (ZF) and transverse field annealing (TF) conditions. A reduction in coercivity for TF samples with respect to ZF sample (16 and 45 A/m, respectively) is observed. Kerr microscopy images show a well-defined parallel domain structure, transversally oriented to the ribbon axis for the TF sample unlike for the ZF sample, for which a complex pattern is observed with large and small domains at the surface of the ribbon. Although Mössbauer spectra are clearly different for the two studied samples, Mössbauer studies confirm that there is no significant difference between the hyperfine field distributions of TF and ZF samples but only the relative intensity of the 2nd and 3rd lines A 23 (related to the angle between the gamma radiation and the magnetic moments, α). However, for TF annealed samples α = 90 deg ( A 23 = 4), indicating that the magnetic moments lay on the plane of the ribbon in agreement with the well-defined domain structure observed by Kerr microscopy, ZF annealed samples show A 23 = 1.8. This value is close to that of a random orientation ( A 23 = 2) but smaller, indicating a slight preference for out of plane orientations. Moreover, it is clearly smaller than that of the as-cast amorphous samples A 23 = 2.8, with a preference to in-plane orientations. The application of the law of approach to saturation yields a larger effect of the inhomogeneities in ZF sample with respect to TF one.

  10. Microstructural modifications of Ni-Ti shape memory alloy thin films induced by electronic stopping of high-energy heavy ions

    International Nuclear Information System (INIS)

    The current study is part of an overarching goal to develop an ion implantation process for producing cyclic actuating elements used in microelectromechanical systems. The damage produced by high-energy ions can be used as a means to selectively suppress the martensitic transformation and bias the motion of shape memory alloy thin films Ni-Ti. In order to optimize the performance of these devices, detailed knowledge of the influence of ion implantation on the microstructure is needed. Recent experiments have shown that complex microstructures are formed after 5 MeV Ni ion implantation. In particular, the extensive surface amorphization and the depth distributions of the irradiation induced phase transformations, which were more prominent at shallower depths than expected, did not correlate with ion transport theories involving nuclear stopping damage distributions. Although electronic stopping effects are normally neglected in metals in these energy regimes, they may explain the unexpected surface amorphization since electronic stopping is the prevalent mode of ion energy transfer at shallow depths. Therefore, swift ion irradiation experiments were conducted to assess the effects of electronic stopping on the damage production. Microstructural observations showed that significant damage was produced from ions possessing low electronic stopping powers (<9 keV/nm) near those of 5 MeV Ni ions (3 keV/nm), confirming, in part, that electronic stopping effects contribute to the damage processes

  11. Microstructural modifications of Ni-Ti shape memory alloy thin films induced by electronic stopping of high-energy heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    LaGrange, T. [Lawrence Livermore National Laboratory, 7000 East Avenue, P.O. Box 808, Mailstop L-353, Livermore, CA 94550 (United States); Abromeit, C. [Hahn Meitner Institute, Glienicker Strasse 100, D-14109 Berlin (Germany); Gotthardt, R. [Swiss Federal Institute of Technology Lausanne (EPFL), Institute of Physics of Complex Matter (IPMC), CH-1015 Lausanne (Switzerland)]. E-mail: rolf.gotthardt@epfl.ch

    2006-11-25

    The current study is part of an overarching goal to develop an ion implantation process for producing cyclic actuating elements used in microelectromechanical systems. The damage produced by high-energy ions can be used as a means to selectively suppress the martensitic transformation and bias the motion of shape memory alloy thin films Ni-Ti. In order to optimize the performance of these devices, detailed knowledge of the influence of ion implantation on the microstructure is needed. Recent experiments have shown that complex microstructures are formed after 5 MeV Ni ion implantation. In particular, the extensive surface amorphization and the depth distributions of the irradiation induced phase transformations, which were more prominent at shallower depths than expected, did not correlate with ion transport theories involving nuclear stopping damage distributions. Although electronic stopping effects are normally neglected in metals in these energy regimes, they may explain the unexpected surface amorphization since electronic stopping is the prevalent mode of ion energy transfer at shallow depths. Therefore, swift ion irradiation experiments were conducted to assess the effects of electronic stopping on the damage production. Microstructural observations showed that significant damage was produced from ions possessing low electronic stopping powers (<9 keV/nm) near those of 5 MeV Ni ions (3 keV/nm), confirming, in part, that electronic stopping effects contribute to the damage processes.

  12. Effect of H{sub 2}S partial pressure and pH of test solution on hydrogen induced cracking of high strength low alloy steels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Wan Keun; Koh, Seong Ung; Kim, Kyoo Young [Pohang University of Science and Technology, Pohang (Korea, Republic of); Yang, Boo Young; Jung, Hwan Kyo [Pohang Iron and Steel Co., Pohang (Korea, Republic of)

    2005-12-15

    Hydrogen induced cracking (HIC) is one of the hydrogen degradation phenomena of line pipe steels caused by H{sub 2}S gas in the crude oil or natural gas. However, NACE TM0284-96 standard HIC test method is hard to satisfy the steel requirements for sour service application since it uses more severe environmental conditions than actual conditions. Therefore, in order to use steels effectively, it is required to evaluate HIC resistance of steels in the practical range of environmental severity. In this study, HIC resistance of two high strength low alloy (HSLA) steels being used as line pipe steels was evaluated in various test solutions with different H{sub 2}S pressures and pH values. The results showed that the key parameter affecting crack area ratio (CAR) is H{sub 2}S partial pressure of test solution when the pH value of test solution is not over 4. Hydrogen diffusivity was not a constant value, but it was rather affected by the hydrogen ion concentration (pH value) in the solution

  13. Aging-induced complex transformation behavior of martensite in Ni57.5Mn17.5Ga25 shape memory alloy

    OpenAIRE

    Khovailo, V. V.; Kainuma, R.; Abe, T.; Oikawa, K; Takagi, T.

    2004-01-01

    Ni57.5Mn17.5Ga25 shape memory alloy exhibits a complex transformation behavior, appearing after aging. Aging in the austenitic state resulted in an ordinary decrease of the martensitic transformation temperature. Contrary to this, aging in the martensitic state brought about unusual features of the martensitic transformation observed so far only in Ni-Ti alloys.

  14. Quantitative Analysis of Dynamic Softening Behaviors Induced by Dynamic Recrystallization for Ti-10V-2Fe-2Al Alloy

    Science.gov (United States)

    Quan, Guozheng; Pu, Shiao; Wen, Hairong; Zou, Zhenyu; Zhou, Jie

    2015-10-01

    In order to investigate the effect of dynamic recrystallization (DRX) behavior on dynamic softening behavior of wrought Ti-10V-2Fe-3Al titanium alloy, a series of laboratory scale isothermal hot compression tests with a height reduction of 60% were performed in a temperature range of 948 K 1023 K in the (σ + β) phase field, and a strain rate range of 0.01 10 s-1 on a Gleeble-3500 thermo-mechanical simulator. The flow curves show a continuous softening at all strain rate after peak stress. The constitutive equation and the DRX kinetic mold were established to study the dynamic softening based on the flow curves. By the regression analysis for conventional hyperbolic sine equation, the activation energy was determined as Q = 479.4169 kJ·mol-1, According to the strain hardening rate curves (dσ/dɛ versus σ), two characteristic parameters including the critical strain for DRX initiation (ɛc) and the strain for peak stress (ɛp) were identified, and the linear dependence of the critical strain (ɛc) for DRX initiation on the strain for peak stress (ɛp) can be specified by the equation: ɛc = 0.5667ɛp. A modified Avrami type equation X_{DRX} = 1 - exp[-β_{d}(\\varepsilon - \\varepsilon_c over \\varepsilon_{0.5})k_d] was introduced to characterize the evolution of DRX volume fraction. The evolution of DRX volume was described as the following: for a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing deformation temperature, in contrast, for a fixed temperature, it increases with increasing strain rate. Finally, the impact of dynamic recrystallized behavior on degree of dynamic softening became weaker and weaker with the increasing of temperature for the strain rate of 0.01 s-1, 0.1 s-1, 1 s-1 and 10 s-1, due to the volume of α phase decreased with the increasing of temperature.

  15. Analysis of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-Ray Emission

    OpenAIRE

    Frey, Alyssa A.; Nicholas R. Wozniak; Nagi, Timothy B.; Keller, Matthew P.; J. Mark Lunderberg; Peaslee, Graham F.; Paul A. DeYoung; Hampton, Jennifer R.

    2011-01-01

    The elemental composition of electrodeposited NiFe thin films was analyzed with particle-induced X-ray emission (PIXE). The thin films were electrodeposited on polycrystalline Au substrates from a 100 mM NiSO4, 10 mM FeSO4, 0.5 M H3BO3, and 1 M Na2SO4 solution. PIXE spectra of these films were analyzed to obtain relative amounts of Ni and Fe as a function of deposition potential and deposition time. The results show that PIXE can measure the total deposited metal in a sample over at least fou...

  16. Hydrogen-induced microstructure, texture and mechanical property evolutions in a high-pressure torsion processed zirconium alloy

    International Nuclear Information System (INIS)

    The gaseous hydriding-induced evolutions of the microstructure, texture and mechanical properties of Zircaloy-4 processed by high-pressure torsion (HPT) were assessed. Much δ-ZrH1.66 precipitation at 15 atm (21%) incurred significant hardening of vacuum-annealed HPT samples, and pure ε-ZrH2 obtained at 20 atm showed a superior microhardness of 470 HV0.3 and a low fracture toughness of 0.63 MPa m1/2. The δ-hydrides presented strong (1 1 1) texture and followed the (0 0 0 1)α-Zr//{1 1 1}δ-ZrH1.66 orientation relationship with the α-Zr matrix. During hydriding, α-Zr recrystallization texture was developed from the initial deformation texture.

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

    Science.gov (United States)

    Mao, Ho-kwang; Mao, Wendy L.

    2011-11-29

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

  18. Nanocrystalline alloy Fe73.5Cu1Nb3Si13.5B9. Its structure and magnetic properties. II. Thermal stability of the induced magnetic anisotropy

    International Nuclear Information System (INIS)

    The specimens of alloy Fe73.5Cu1Nb3Si13.5B9 produced as amorphous ribbons by quenching from the melt to a rotating wheel are used to study thermal stability of a constant of magnetic anisotropy Ku, induced in the process of thermomechanical or thermomagnetic treatments. The conditions of magnetic anisotropy induction (holding time and the intensity of external action) for obtaining expected thermal stability of Ku, are elucidated. Transmission electron microscopical studies show some distinctions in the alloy microstructure after different treatments. A comparison of results of magnetic and structural investigations, carried out by Moessbauer method, permits the assumption that the phases containing niobium and boron along with iron are responsible for thermal stability of Ku

  19. Distributions of C22-C30 even-carbon-number n-alkanes in Ocean Anoxic Event 1 samples from the Basque-Cantabrian Basin.

    Science.gov (United States)

    Chaler, R; Dorronsoro, C; Grimalt, J O; Agirrezabala, L M; Fernández-Mendiola, P A; García-Mondejar, J; Gómez-Pérez, I; López-Horgue, M

    2005-05-01

    The Ocean Anoxic Event 1 (OAE-1) in central sites of the Basque-Cantabrian Basin exhibits very reducing depositional conditions of sedimentation. These sedimentation events have left a distinct mixture of hydrocarbons that are represented by C22-C30 n-alkanes with a predominance of the even-carbon-number homologues, high relative proportions of squalane and C16-C24 n-alkylcyclopentanes predominated by n-undecyl-, n-tridecyl- and n-pentadecylcyclopentane. Other minor compounds encompass a series of C18-C21 n-alkylcyclohexanes and C18-C24 dimethyl n-alkylcyclohexanes maximized by the even-carbon-number homologues as well as iso- and anteiso-alkanes. This unusual distribution of n-alkanes in this environment provides a new case for comparison with previously reported hypersaline and phosphorite sedimentary deposits where the occurrence of similar n-alkane distributions was reported. In the present case, these major n-alkanes and squalane are indicative of transformation under strong reducing conditions. In contrast, the occurrence of the alkylcyclopentanes, irrespective of the presence of even-carbon-number n-alkanes or squalane, suggests that reductive cyclization of fatty acids is less dependent on strong reducing conditions. PMID:15776255

  20. Multifractal analysis of 4.1A GeV/c 22Ne and 4.5A GeV/c 28Si collisions with emulsion

    International Nuclear Information System (INIS)

    The fractal or intermittent behaviour has been investigated for the non-peripheral-collisions of 4.1A GeV/c 22Ne and 4.5A GeV/c 28Si with emulsion using the scaled factorial moments and the multifractal in the pseudorapidity, the azimuthal angle and in the two-dimensional phase spaces. The reduced scaled factorial moments as a function of the bin size in pseudorapidity, azimuthal angle and the pseudorapidity-azimuthal angle spaces have been calculated and have revealed the presence of an intermittent behavior. It has been shown that the magnitude of the anomalous fractal dimension increases with the rank of the moment in all the investigates spaces. In the relation between the intermittency parameter and the rank of the moment, no obvious minimum has been observed. However, in the azimuthal angle space for 28Si data, a flattering is seen around the value 4 for the rank of the moment. The analysis of the present data may indicate the random cascading property of the reactions. The results do not give a clear signal for the coexistence of two phases of the self-similar cascade

  1. Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na and 36Cl in the atmosphere: Altitudinal profiles of yield functions

    CERN Document Server

    Poluianov, Stepan; Mishev, Alexander L; Usoskin, Ilya G

    2016-01-01

    New consistent and precise computations of the production of five cosmogenic radio-isotopes, 7Be, 10Be, 14C, 22Na and 36Cl, in the Earth's atmosphere by cosmic rays are presented in the form of tabulated yield functions. For the first time, a detailed set of the the altitude profiles of the production functions is provided which makes it possible to apply the results directly as input for atmospheric transport models. Good agreement with most of the earlier published works for columnar and global isotopic production rates is shown. Altitude profiles of the production are important, in particular for such tasks as studies of strong solar particle events in the past, precise reconstructions of solar activity on long-term scale, tracing air-mass dynamics using cosmogenic radio-isotopes, etc. As an example, computations of the $^{10}$Be deposition flux in the polar region are shown for the last decades and also for a period around 780 AD and confronted with the actual measurements in Greenland and Antarctic ice c...

  2. Evaluation of the prediction precision capability of partial least squares regression approach for analysis of high alloy steel by laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Arnab, E-mail: asarkar@ymail.com [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Karki, Vijay; Aggarwal, Suresh K. [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Maurya, Gulab S.; Kumar, Rohit; Rai, Awadhesh K. [Department of Physics, University of Allahabad, Allahabad 211002 (India); Mao, Xianglei [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Russo, Richard E., E-mail: rerusso@lbl.gov [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)

    2015-06-01

    Laser induced breakdown spectroscopy (LIBS) was applied for elemental characterization of high alloy steel using partial least squares regression (PLSR) with an objective to evaluate the analytical performance of this multivariate approach. The optimization of the number of principle components for minimizing error in PLSR algorithm was investigated. The effect of different pre-treatment procedures on the raw spectral data before PLSR analysis was evaluated based on several statistical (standard error of prediction, percentage relative error of prediction etc.) parameters. The pre-treatment with “NORM” parameter gave the optimum statistical results. The analytical performance of PLSR model improved by increasing the number of laser pulses accumulated per spectrum as well as by truncating the spectrum to appropriate wavelength region. It was found that the statistical benefit of truncating the spectrum can also be accomplished by increasing the number of laser pulses per accumulation without spectral truncation. The constituents (Co and Mo) present in hundreds of ppm were determined with relative precision of 4–9% (2σ), whereas the major constituents Cr and Ni (present at a few percent levels) were determined with a relative precision of ~ 2%(2σ). - Highlights: • The quantification of Cr, Ni, Mn, Si, Co and Mo in steel by LIBS was carried out. • PLSR1 based multivariate calibration was used for construction of calibrations. • Alternative spectral pre-treatment procedures were applied on spectra. • The effect of selected regions of interest on PLSR1 was studied. • The effect of the number of laser shots per spectrum was studied.

  3. Evaluation of the prediction precision capability of partial least squares regression approach for analysis of high alloy steel by laser induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Laser induced breakdown spectroscopy (LIBS) was applied for elemental characterization of high alloy steel using partial least squares regression (PLSR) with an objective to evaluate the analytical performance of this multivariate approach. The optimization of the number of principle components for minimizing error in PLSR algorithm was investigated. The effect of different pre-treatment procedures on the raw spectral data before PLSR analysis was evaluated based on several statistical (standard error of prediction, percentage relative error of prediction etc.) parameters. The pre-treatment with “NORM” parameter gave the optimum statistical results. The analytical performance of PLSR model improved by increasing the number of laser pulses accumulated per spectrum as well as by truncating the spectrum to appropriate wavelength region. It was found that the statistical benefit of truncating the spectrum can also be accomplished by increasing the number of laser pulses per accumulation without spectral truncation. The constituents (Co and Mo) present in hundreds of ppm were determined with relative precision of 4–9% (2σ), whereas the major constituents Cr and Ni (present at a few percent levels) were determined with a relative precision of ~ 2%(2σ). - Highlights: • The quantification of Cr, Ni, Mn, Si, Co and Mo in steel by LIBS was carried out. • PLSR1 based multivariate calibration was used for construction of calibrations. • Alternative spectral pre-treatment procedures were applied on spectra. • The effect of selected regions of interest on PLSR1 was studied. • The effect of the number of laser shots per spectrum was studied

  4. Evaluation of Conditions for Hydrogen Induced Degradation of Zirconium Alloys during Fuel Operation and Storage. Final Report of a Coordinated Research Project 2011-2015

    International Nuclear Information System (INIS)

    This publication reports on the work carried out in 2011–2015 in the coordinated research project (CRP) on the evaluation of conditions for hydrogen induced degradation of zirconium alloys during fuel operation and storage. The CRP was carried out to evaluate the threshold condition for delayed hydride cracking (KIH) in pressurized water reactors and zircaloy-4 and E635M fuel claddings, with application to in-pile operation and spent fuel storage. The project consisted of adding hydrogen to samples of cladding and measuring KIH by one of four methods. The CRP was the third in the series, of which the results of the first two were published in IAEA-TECDOC-1410 and IAEA-TECDOC-1649, in 2004 and 2010, respectively. This publication includes all of the research work performed in the framework of the CRP, including details of the experimental procedures that led to a set of data for tested materials. The research was conducted by representatives from 13 laboratories from all over the world. In addition to the basic goal to transfer the technology of the testing techniques from experienced laboratories to those unfamiliar with the methods, the CRP was set up to develop experimental procedures to produce consistent sets of data, both within a single laboratory and among different laboratories. The material condition and temperature history were prescribed, and laboratories chose one or two of four methods of loading that were recommended in an attempt to develop standard sets of experimental protocols so that consistent results could be obtained. Experimental discrepancies were minimized through careful attention to details of microstructure, temperature history and stress state in the samples, with the main variation being the mode of loading

  5. Effect of microstructure on ion-irradiation-induced hardening in A533B model alloys at 563K

    International Nuclear Information System (INIS)

    Irradiation-induced hardening was investigated in reactor pressure vessel steels, A533B, irradiated with 2.8MeV Fe2+ ion dose up to 1dpa with dose rate ranging from 10-5 to 10-3dpa/s at 563K. Alteration of local hardness was intensively measured as a function of dose and dose rate. To evaluate the local hardness, nano-indentation technique was employed to clarify the effect of microstructure, which is ferrite matrix and embedded colonial carbides. Hardening in the regions was observed with increasing dose, φt. Irradiation hardening of carbide colony regions is greater than ferrite regions higher dose than 0.1dpa. Hardening in the both regions is proportional to φ1/2 up to 1dpa. In the carbide colony region, irradiation hardening at the dose lower than 0.1dpa was greater than that in ferrite region. Effect of dose rate was observed to be more significant at the lower dose in the carbide colony regions. (author)

  6. Magnetic transition induced by mechanical deformation in Fe{sub 60}Al{sub 40−x}Si{sub x} ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Legarra, E., E-mail: estibaliz.legarra@ehu.es [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain); Apiñaniz, E. [Dpto. Fisica Aplicada I, Universidad del Pais Vasco, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Plazaola, F. [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain); Jimenez, J.A. [Centro Nacional de Investigaciones Metalurgicas (CENIM), Avda. Gregorio del amo 8, 28040 Madrid (Spain)

    2014-02-15

    Highlights: • Fe{sub 60}Al{sub 40−x}Si{sub x} alloys were disordered by means of planetary ball milling technique. • Paramagnetic to ferromagnetic transition is observed with disordering. • Si addition hinders the disordering process and the increase of the lattice parameter. • Si addition promotes the paramagnetic to ferromagnetic transition. -- Abstract: We have used Mössbauer spectroscopy and X-ray diffraction to study the influence of different Al/Si ratios on the structural and magnetic properties of the mechanically deformed Fe{sub 60}Al{sub 40−x}Si{sub x} alloys. The results indicate that ternary alloys also present the magnetic transition with disordering observed in binary Fe{sub 60}Al{sub 40} alloys. Besides, Si introduction has two opposite contributions. From a structural point of view, hinders the disordering process, but, from a magnetic point of view promotes the magnetic transition.

  7. Mechanically driven nanocrystallization of amorphous Fe73.5Cu1Nb3Si13.5B9 alloy induced by high-energy ball milling

    International Nuclear Information System (INIS)

    The mechanically driven nanocrystallization of amorphous Finemet alloy caused by high-energy ball milling was investigated by XRD, DSC and TEM techniques. A structural relaxation occurred in the amorphous Finemet alloy after milling for 0.5-2 h. Further milling for more than 3.5 h, uniformly and randomly distributed nanocrystalline α-Fe with grain size from ∝2 nm to ∝5 nm formed. The kinetics of the mechanical nanocrystallization of amorphous Finemet alloy was described by JMA model with the Avrami exponent n=1.55, which indicates a zero-nucleation rate and grain growth in all shapes from very small dimensions. In addition, the mechanical crystallization of amorphous Finemet alloys is mainly due to the severe deformation and local temperature rise during ball milling. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Stress and annealing induced changes in the Curie temperature of amorphous and nanocrystalline FeZr and FeNb based alloys

    International Nuclear Information System (INIS)

    The stress and annealing dependence of the Curie temperature in FeZrBCu alloys is presented. A change of about 50 /GPa has been observed. The change in amorphous matrix composition upon crystallization produces an expected increase in TC (about 200 C) which is similar to the experimentally observed increase. This behaviour is opposite to that observed in Fe-Nb based alloys. (orig.)

  9. Functional characterization of CYP71D443, a cytochrome P450 catalyzing C-22 hydroxylation in the 20-hydroxyecdysone biosynthesis of Ajuga hairy roots.

    Science.gov (United States)

    Tsukagoshi, Yuki; Ohyama, Kiyoshi; Seki, Hikaru; Akashi, Tomoyoshi; Muranaka, Toshiya; Suzuki, Hideyuki; Fujimoto, Yoshinori

    2016-07-01

    20-Hydroxyecdysone (20HE), a molting hormone of insects, is also distributed among a variety of plant families. 20HE is thought to play a role in protecting plants from insect herbivores. In insects, biosynthesis of 20HE from cholesterol proceeds via 7-dehydrocholesterol and 3β,14α-dihydroxy-5β-cholest-7-en-6-one (5β-ketodiol), the latter being converted to 20HE through sequential hydroxylation catalyzed by four P450 enzymes, which have been cloned and identified. In contrast, little is known about plant 20HE biosynthesis, and no biosynthetic 20HE gene has been reported thus far. We recently proposed involvement of 3β-hydroxy-5β-cholestan-6-one (5β-ketone) in 20HE biosynthesis in the hairy roots of Ajuga reptans var. atropurpurea (Lamiaceae). In this study, an Ajuga EST library was generated from the hairy roots and P450 genes were deduced from the library. Five genes with a high expression level (CYP71D443, CYP76AH19, CYP76AH20, CYP76AH21 and CYP716D27) were screened for a possible involvement in 20HE biosynthesis. As a result, CYP71D443 was shown to have C-22 hydroxylation activity for the 5β-ketone substrate using a yeast expression system. The hydroxylated product, 22-hydroxy-5β-ketone, had a 22R configuration in agreement with that of 20HE. Furthermore, labeling experiments indicated that (22R)-22-hydroxy-5β-ketone was converted to 20HE in Ajuga hairy roots. Based on the present results, a possible 20HE biosynthetic pathway in Ajuga plants involved CYP71D443 is proposed. PMID:27017303

  10. Effect of alloy composition on the sodium-sulfate induced hot corrosion attack of cast nickel-base superalloys at 900 C

    Science.gov (United States)

    Stearns, C. A.; Deadmore, D. L.; Barrett, C. A.

    1987-01-01

    The effects of Cr, Al, Ti, Mo, Ta, Nb, and W content on the hot corrosion of Ni-base alloys were examined experimentally. The superalloys were tested for 300 1-hr cycles at 900 C in a Mach 0.3 burner rig flame containing 0.5 ppmw sodium. The data reveal that the best corrosion resistance is obtained when the Cr content is greater than 12 percent; however, good resistance is detected in some alloys with Cr content less than 10 percent provided that the Al content is less than 2.5 wt pct and the Ti content is less than 4 wt pct. It is observed that the influence of W, Ta, Mo, and Nb content on resistance is dependent on Al and Ti contents. The derivation of an equation for estimating hot corrosion attack as a function of alloy composition using multiple linear regression analysis is described. The applicability of the equation is tested using various data sets of alloys. It is noted that the equation can be used to explain the effects of alloy composition on attack rates.

  11. Influences of hydrogen-induced amorphization and annealing treatment on gaseous hydrogen storage properties of La{sub 1−x}Pr{sub x}MgNi{sub 3.6}Co{sub 0.4} (x = 0–0.4) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Tingting [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); College of Science, Northeastern University, Shenyang 110819 (China); Yang, Tai; Yuan, Zeming; Xu, Sheng; Bu, Wengang [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Qi, Yang [College of Science, Northeastern University, Shenyang 110819 (China); Zhang, Yanghuan, E-mail: zhangyh59@sina.com [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China)

    2015-08-05

    Highlights: • The La–Mg–Ni-based AB{sub 2}-type alloys were prepared by casting. • La was substituted by a small amount of Pr in the experimental alloys. • The hydrogen absorption/desorption cycling properties of the alloys were studied. • The influences of hydrogen-induced amorphization were investigated in details. • The annealing treatment was applied to recover hydrogen storage capacity. - Abstract: La{sub 1−x}Pr{sub x}MgNi{sub 3.6}Co{sub 0.4} (x = 0–0.4) alloys are prepared by vacuum induction melting. The phase composition and microstructure of the as-cast alloys is characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The gaseous hydrogen absorption capacity of the alloys was measured by an automatically controlled Sieverts apparatus. The results indicate that the as-cast alloys consist of two phases of LaMgNi{sub 4} and LaNi{sub 5}. The maximum gaseous hydrogen storage capacity of the La{sub 1−x}Pr{sub x}MgNi{sub 3.6}Co{sub 0.4} (x = 0–0.4) alloys is 1.768, 1.745, 1.721, 1.681 and 1.653 wt%, respectively, under 3 MPa H{sub 2} at 373 K. But the hydrogen storage capacity after 20 cycles decays off to 0.746, 0.843, 0.947, 1.003 and 1.10 wt%, respectively. In order to reveal the mechanism of rapid degradation of the capacity, the structures of the alloys before and after hydrogen absorption/desorption cycle were analyzed. SEM observation displays that the micro-cracks can be clearly seen on the surface of the alloy particles after 20 cycles. XRD detection finds that the repeated hydrogen absorption/desorption cycles give rise to a obvious broadening of the diffraction peaks of the alloys, exhibiting a typical amorphous structure, which is termed as hydrogen-induced amorphization. The La{sub 1−x}Pr{sub x}MgNi{sub 3.6}Co{sub 0.4} (x = 0–0.4) alloys after 20 cycles were annealed at 623 K for 8 h, finding that the hydrogen storage capacity of the alloys recovers to 1.348, 1.365, 1.50, 1.485 and 1.30 wt

  12. Vanadium alloys: development strategy

    International Nuclear Information System (INIS)

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

  13. Hydrogen effects in aluminum alloys

    International Nuclear Information System (INIS)

    The permeability of six commercial aluminum alloys to deuterium and tritium was determined by several techniques. Surface films inhibited permeation under most conditions; however, contact with lithium deuteride during the tests minimized the surface effects. Under these conditions phi/sub D2/ = 1.9 x 10-2 exp (--22,400/RT) cc (NTP)atm/sup --1/2/ s-1cm-1. The six alloys were also tested before, during, and after exposure to high pressure hydrogen, and no hydrogen-induced effects on the tensile properties were observed

  14. Dynamic precipitation of Mg{sub 2}Si induced by temperature and strain during hot extrusion and its impact on microstructure and mechanical properties of near eutectic Al–Si–Mg–V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yuna; Liao, Hengcheng, E-mail: hengchengliao@seu.edu.cn; Liu, Yabing; Zhou, Kexin

    2014-09-22

    Dynamic precipitation of Mg{sub 2}Si and its impact on the microstructures and mechanical properties of Al–12.5 wt% Si–0.6 wt% Mg–0.1 wt% V alloy were studied by applying different extrusion temperatures and extrusion ratios. Optical microscopy (OM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) observations were used to characterize the microstructure evolution. Tensile properties and the Brinell hardness were tested. Results show that both decreasing extrusion temperature (temperature-induced) and increasing extrusion ratio (strain-induced) of the alloy will result in dynamic precipitation of Mg{sub 2}Si particles. Dynamic precipitation of Mg{sub 2}Si leads to a considerable coarsening of the recrystallized grains. Yield strength (YS) and ultimate tensile strength (UTS) of the sample extruded at lower temperature (400 °C) are more than 50% lower than that extruded at higher temperature (540 °C) with the same extrusion ratio of 16. With increasing of extrusion ratio from 16 to 50, both YS and UTS of the samples decrease nearly 30% when extruded at the same temperature of 540 °C.

  15. Stress corrosion cracking of Ni-base and Ti alloys under controlled potential

    International Nuclear Information System (INIS)

    Susceptibility to stress corrosion cracking (SCC) of alloy C-22 and Ti Gr-12, two candidate alloys for the inner-container of the multi-barrier nuclear waste package, was evaluated by using the slow-strain-rate (SSR) test technique in a deaerated acidic brine (pH ∼ 2.70) at 90 C. The strain rate used was 3.3 x 10-6 sec-1. Prior to being tested in the acidic brine, specimens of each alloy were pulled inside the test chamber in the dry condition at room temperature (RT). Then specimens were exposed to the test solution while being strained under different controlled electrochemical potentials. The magnitude of the controlled potential was selected based on the corrosion potential measured in the test solution prior to straining of the specimen. Results indicate that, for Ti Gr-12, the times to failure were significantly shorter compared to those for alloy C-22. Furthermore, Ti Gr-12 showed reduced ductility in terms of percent reduction in area and true fracture stress, as the controlled potential became more cathodic. Results also indicate that the time-to-failure and percent elongation reached the minimum values when Ti Gr-12 was tested under impressed potential of -1162 mV. Finally, metallographic examination was performed to evaluate the primary fracture, and the secondary cracking, if any, along the gage section of the broken tensile specimen

  16. Activation analyses for different fusion structural alloys

    International Nuclear Information System (INIS)

    The leading candidate structural materials, viz., the vanadium alloys, the nickel or the manganese stabilized austenitic steels, and the ferritic steels, are analysed in terms of their induced activation in the TPSS fusion power reactor. The TPSS reactor has 1950 MW fusion power and inboard and outboard average neutron wall loading of 3.75 and 5.35 MW/m2 respectively. The results shows that, after one year of continuous operation, the vanadium alloys have the least radioactivity at reactor shutdown. The maximum difference between the induced radioactivity in the vanadium alloys and in the other iron-based alloys occurs at about 10 years after reactor shutdown. At this time, the total reactor radioactivity, using the vanadium alloys, is about two orders of magnitude less than the total reactor radioactivity utilizing any other alloy. The difference is even larger in the first wall, the FW-vanadium activation is 3 orders of magnitude less than other alloys' FW activation. 2 refs., 7 figs

  17. Translating VDM to Alloy

    DEFF Research Database (Denmark)

    Lausdahl, Kenneth

    2013-01-01

    specifications. However, to take advantage of the automated analysis of Alloy, the model-oriented VDM specifications must be translated into a constraint-based Alloy specifications. We describe how a sub- set of VDM can be translated into Alloy and how assertions can be expressed in VDM and checked by the Alloy...

  18. A jumping shape memory alloy under heat

    OpenAIRE

    Shuiyuan Yang; Toshihiro Omori; Cuiping Wang; Yong Liu; Makoto Nagasako; Jingjing Ruan; Ryosuke Kainuma; Kiyohito Ishida; Xingjun Liu

    2016-01-01

    Shape memory alloys are typical temperature-sensitive metallic functional materials due to superelasticity and shape recovery characteristics. The conventional shape memory effect involves the formation and deformation of thermally induced martensite and its reverse transformation. The shape recovery process usually takes place over a temperature range, showing relatively low temperature-sensitivity. Here we report novel Cu-Al-Fe-Mn shape memory alloys. Their stress-strain and shape recovery ...

  19. Transformation yield surface of shape memory alloys

    OpenAIRE

    K. Bhattacharya; Schlömerkemper, A

    2004-01-01

    Shape-memory alloys transform under stress, and this stress-induced transformation is useful for various practical applications. The stress at which the alloy transforms depends on the orientation of the stress relative to the specimen, and may be described using a transformation yield surface. This paper provides early results of a theoretical treatment of the transformation yield surface of shape-memory polycrystals with particular emphasis on the influence of texture.

  20. LASER CLADDING ON ALUMINIUM BASE ALLOYS

    OpenAIRE

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

    1991-01-01

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

  1. A Clinical Isolate of Candida albicans with Mutations in ERG11 (Encoding Sterol 14α-Demethylase) and ERG5 (Encoding C22 Desaturase) Is Cross Resistant to Azoles and Amphotericin B▿

    OpenAIRE

    Martel, Claire M.; Parker, Josie E.; Bader, Oliver; Weig, Michael; Gross, Uwe; Warrilow, Andrew G. S.; Kelly, Diane E.; Kelly, Steven L.

    2010-01-01

    A clinical isolate of Candida albicans was identified as an erg5 (encoding sterol C22 desaturase) mutant in which ergosterol was not detectable and ergosta 5,7-dienol comprised >80% of the total sterol fraction. The mutant isolate (CA108) was resistant to fluconazole, voriconazole, itraconazole, ketoconazole, and clotrimazole (MIC values, 64, 8, 2, 1, and 2 μg ml−1, respectively); azole resistance could not be fully explained by the activity of multidrug resistance pumps. When susceptibility ...

  2. Phase field-finite element approach to study the effects of plasticity on thermal- and stress-induced martensite in shape memory alloys

    OpenAIRE

    Paranjape, Harshad; Manchiraju, Sivom; Bowers, Matthew; Mills, Michael; Anderson, Peter

    2014-01-01

    Numerous experimental studies have shown that evolution of the martensite microstructure in shape memory alloys can lead to plastic deformation. This results in poor functional fatigue in many commercial applications, whereby strain incrementally advances with repeated thermal cycling under stress. This can also affect structural fatigue, whereby repeated cycling initiates and grows fatigue cracks. Conventional strategies to improve fatigue life include increasing flow strength as to decrease...

  3. In vitro and in vivo studies on biodegradable magnesium alloy

    Directory of Open Access Journals (Sweden)

    Lida Hou

    2014-10-01

    Full Text Available The microstructure, mechanical property, electrochemical behavior and biocompatibility of magnesium alloy (BioDe MSM™ were studied in the present work. The experimental results demonstrated that grain refining induced by extrusion improves the alloy strength significantly from 162 MPa for the as-cast alloy to 241 MPa for the as-extruded one. The anticorrosion properties of the as-extruded alloy also increased. Furthermore, the hemolysis ratio was decreased from 4.7% for the as-cast alloy to 2.9% for the as-extruded one, both below 5%. BioDe MSM™ alloy shows good biocompatibility after being implanted into the dorsal muscle and the femoral shaft of the New Zealand rabbit, respectively, and there are no abnormalities after short-term implantation. In vivo observation indicated that the corrosion rate of this alloy varies with different implantation positions, with higher degradation rate in the femur than in the muscle.

  4. Alloyed steel

    International Nuclear Information System (INIS)

    The composition and properties are listed of alloyed steel for use in the manufacture of steam generators, collectors, spacers, emergency tanks, and other components of nuclear power plants. The steel consists of 0.08 to 0.11% w.w. C, 0.6 to 1.4% w.w. Mn, 0.35 to 0.6% w.w. Mo, 0.02 to 0.07% w.w. Al, 0.17 to 0.37% w.w. Si, 1.7 to 2.7% w.w. Ni, 0.03 to 0.07% w.w. V, 0.005 to 0.012% w.w. N, and the rest is Fe. The said steel showed a sufficiently low transition temperature between brittle and tough structures, a greater depth of hardenability, and better weldability than similar steels. (B.S.)

  5. Texture in two cold-drawn beta Ti alloys

    International Nuclear Information System (INIS)

    Synchrotron X-ray diffraction was used to measure the textures in two heavily cold-drawn beta Ti alloys (i.e. beta III Ti alloy and Ti–15Mo alloy). Instead of the well-known β texture, the β texture was found in the cold-drawn condition along with a strong ω texture. The cause of the texture in the β phase is possibly related to the stress-induced omega phase transformation during the cold-drawing process

  6. Crystallographic orientation-spray formed hypereutectic aluminium-silicon alloys

    OpenAIRE

    Hamilta de Oliveira Santos; Marilene Morelli Serna; Nelson Batista de Lima; Isolda Costa; Jesualdo Luiz Rossi

    2005-01-01

    Aluminium-silicon alloys have been wide accepted in the automotive, electric and aerospace industries. Preferred orientation is a very common condition for metals and alloys. Particularly, aluminium induces texture during the forming process. The preparation of an aggregate with completely random crystal orientation is a difficult task. The present work was undertaken to analyse the texture by X-ray diffraction techniques, of three spray formed hypereutectic Al-Si alloys. Samples were taken f...

  7. Application of the Eyring Equation in the Evaluation of Semi-Solid Forming-Induced Si Particle Refinement in the Hypereutectic Al-Si Alloys

    Science.gov (United States)

    Fukui, Yasuyoshi; Nara, Daisaku; Fushimi, Kazuyo; Kumazawa, Noriyoshi

    2015-12-01

    On the basis of Eyring's theory of absolute reaction rate, an approach to modeling Si particle refinement acceleration in the semi-solid forming of a hypereutectic Al-Si alloy has been developed. The acceleration variable data used in the present analysis were obtained from a semi-solid compression test using Al-25 mass pct Si alloy cylindrical specimens with a diameter of 15 mm and a height of 15 mm; the test conditions comprised a combination of compression displacements ∆ h = 5, 10, and 12 mm; compression rates v = 5, 25, and 125 mm/min; and test temperatures T = 853 K and 863 K (580 °C and 590 °C). The coarse primary Si particle refinement depends on a complex interaction among variables, such as compression displacement, compression rate, and test temperature. The performance of Si particle refinement degraded under higher temperature, slower strain rates, and slower shear rates. The results of the Si particle size are suitably summarized by the Eyring equation as a function of the temperature and the shear rate. The baseline Si particle size and the baseline temperature of Si particle refinement, i.e., the reference temperature, were G N = 0.27 mm and T N = 866.4 K (593.4 °C), respectively. The calculated results using this equation correlated well with the observed results. An acceleration factor of Si particle refinement was successfully derived on the basis of this equation and indicated that operating at a higher shear rate and a temperature just above the melting point of eutectic Al-Si alloy are the optimum conditions for refining Si particles.

  8. Study on the nanostructure formation mechanism of hypereutectic Al–17.5Si alloy induced by high current pulsed electron beam

    International Nuclear Information System (INIS)

    This work investigates the nanostructure forming mechanism of hypereutectic Al–17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1)Al//(0 0 1)Si with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al–Si alloys

  9. Plastic Instabilities Induced by the Portevin - Le Châtelier Effect and Fracture Character of Deformed Mg-Li Alloys Investigated Using the Acoustic Emission Method

    Directory of Open Access Journals (Sweden)

    Pawełek A.

    2016-06-01

    Full Text Available The results of the investigation of both mechanical and acoustic emission (AE behaviors of Mg4Li5Al and Mg4Li4Zn alloys subjected to compression and tensile tests at room temperature are compared with the test results obtained using the same alloys and loading scheme but at elevated temperatures. The main aim of the paper is to investigate, to determine and to explain the relation between plastic flow instabilities and the fracture characteristics. There are discussed the possible influence of the factors related with enhanced internal stresses such as: segregation of precipitates along grain boundaries, interaction of solute atoms with mobile dislocations (Cottrell atmospheres as well as dislocation pile-ups which may lead to the microcracks formation due to the creation of very high stress concentration at grain boundaries. The results show that the plastic flow discontinuities are related to the Portevin-Le Châtelier phenomenon (PL effect and they are correlated with the generation of characteristic AE pulse trains. The fractography of broken samples was analyzed on the basis of light (optical, TEM and SEM images.

  10. Study on the nanostructure formation mechanism of hypereutectic Al–17.5Si alloy induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bo, E-mail: gaob@smm.neu.edu.cn [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Hu, Liang [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Li, Shi-wei [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Hao, Yi [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Zhang, Yu-dong [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France); Tu, Gan-feng [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Grosdidier, Thierry [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France)

    2015-08-15

    This work investigates the nanostructure forming mechanism of hypereutectic Al–17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1){sub Al}//(0 0 1){sub Si} with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al–Si alloys.

  11. Study on the nanostructure formation mechanism of hypereutectic Al-17.5Si alloy induced by high current pulsed electron beam

    Science.gov (United States)

    Gao, Bo; Hu, Liang; Li, Shi-wei; Hao, Yi; Zhang, Yu-dong; Tu, Gan-feng; Grosdidier, Thierry

    2015-08-01

    This work investigates the nanostructure forming mechanism of hypereutectic Al-17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1)Al//(0 0 1)Si with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al-Si alloys.

  12. Printability of alloys for additive manufacturing.

    Science.gov (United States)

    Mukherjee, T; Zuback, J S; De, A; DebRoy, T

    2016-01-01

    Although additive manufacturing (AM), or three dimensional (3D) printing, provides significant advantages over existing manufacturing techniques, metallic parts produced by AM are susceptible to distortion, lack of fusion defects and compositional changes. Here we show that the printability, or the ability of an alloy to avoid these defects, can be examined by developing and testing appropriate theories. A theoretical scaling analysis is used to test vulnerability of various alloys to thermal distortion. A theoretical kinetic model is used to examine predisposition of different alloys to AM induced compositional changes. A well-tested numerical heat transfer and fluid flow model is used to compare susceptibilities of various alloys to lack of fusion defects. These results are tested and validated with independent experimental data. The findings presented in this paper are aimed at achieving distortion free, compositionally sound and well bonded metallic parts. PMID:26796864

  13. Printability of alloys for additive manufacturing

    Science.gov (United States)

    Mukherjee, T.; Zuback, J. S.; de, A.; Debroy, T.

    2016-01-01

    Although additive manufacturing (AM), or three dimensional (3D) printing, provides significant advantages over existing manufacturing techniques, metallic parts produced by AM are susceptible to distortion, lack of fusion defects and compositional changes. Here we show that the printability, or the ability of an alloy to avoid these defects, can be examined by developing and testing appropriate theories. A theoretical scaling analysis is used to test vulnerability of various alloys to thermal distortion. A theoretical kinetic model is used to examine predisposition of different alloys to AM induced compositional changes. A well-tested numerical heat transfer and fluid flow model is used to compare susceptibilities of various alloys to lack of fusion defects. These results are tested and validated with independent experimental data. The findings presented in this paper are aimed at achieving distortion free, compositionally sound and well bonded metallic parts.

  14. Printability of alloys for additive manufacturing

    Science.gov (United States)

    Mukherjee, T.; Zuback, J. S.; De, A.; DebRoy, T.

    2016-01-01

    Although additive manufacturing (AM), or three dimensional (3D) printing, provides significant advantages over existing manufacturing techniques, metallic parts produced by AM are susceptible to distortion, lack of fusion defects and compositional changes. Here we show that the printability, or the ability of an alloy to avoid these defects, can be examined by developing and testing appropriate theories. A theoretical scaling analysis is used to test vulnerability of various alloys to thermal distortion. A theoretical kinetic model is used to examine predisposition of different alloys to AM induced compositional changes. A well-tested numerical heat transfer and fluid flow model is used to compare susceptibilities of various alloys to lack of fusion defects. These results are tested and validated with independent experimental data. The findings presented in this paper are aimed at achieving distortion free, compositionally sound and well bonded metallic parts. PMID:26796864

  15. 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...

  16. A Detailed Observation on Successive Stress-Induced Martensite Transformation in CuAlMnZnZr Alloy Polycrystalline Above Af

    Institute of Scientific and Technical Information of China (English)

    Li Zhou; Wang Ming-pu; Tang Wang; Guo Ming-xing

    2004-01-01

    The successive stress-induced martensite morphologies and mechanisms in polycrystalline CuAlMnZnZr samples have been examined. By applying stress to the uniform β1 matrix, two or more orientation plates of M18R martensite are stress-induced in a grain. With further increasing stress, one orientation plate depletes the other and coalesces into a single region in some view field. The mechanisms by which these are developed have been ascertained, and include variant-variant coalescence, stress-induced martensite to martensite transformation and the complicated cross-like stress-induced martensite formation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, L; Perepezko, J; Hildal, K

    2007-02-08

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

  18. Hydrogen interactions in aluminum-lithium alloys

    Science.gov (United States)

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

    1991-01-01

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

  19. Terbium base alloy

    International Nuclear Information System (INIS)

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

  20. Microstructure Scaling Properties and Fatigue Resistance of Pre-Strained Aluminium Alloys (Part 1: Al-Cu alloy)

    OpenAIRE

    Froustey, C.; NAIMARK, O.; BANNIKOV, M.; Oborin, V.

    2010-01-01

    Abstract The objective of this work is to provide the link between the fatigue behaviour of pre-strained aluminium alloys and the scaling properties of damage induced on the fracture surface. Fatigue tests performed on pre-strained aluminium alloys revealed a large difference in their residual fatigue resistance linked to the material: the Al-Cu alloy demonstrated a sharp decrease of HCF life-time due to the pre-straining whereas the insensitivity of the Al-Mg alloy was clear. For ...

  1. 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...

  2. Laser-induced reversion of $\\delta^{'}$ precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe

    CERN Document Server

    Khushaim, Muna; Al-Kassab, Talaat

    2015-01-01

    The influence of tuning the laser energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction and composition of $\\delta^{'}$ precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser energy. The results indicated that the corresponding temperatures for the laser energy in the range of 10 to 80 pJ are located inside the miscibility gap of the binary Al-Li phase diagram and fall into the metastable equilibrium field. In addition, the corresponding temperature for a laser energy of 100 pJ was in fairly good agreement with reported range of $\\delta^{'}$ solvus temperature, suggesting a result of reversion upon heating due to laser pulsing.

  3. Correlation between thermal induced structural and magnetic transformations in Si-rich Fe73Cu1Si16B7Nb3 metal alloy

    International Nuclear Information System (INIS)

    Properties of amorphous Fe73Cu1Si16B7Nb3 foil, the Si rich metal alloy, and the foils partly crystallised after annealing, were analysed structurally and magnetically in the temperature range from 4 to 1000 K. The Fe (Si) and Fe (B) structures were identified and characterised with the crystallisation temperatures: 750 and 893 K, activation energies 460 and 580 kJ/mol. The Curie temperatures for amorphous structure: 613 K and for crystalline structures: 820, 875, 920 and 980 K were determined. It was found and analysed a delay of the sample magnetisation, determined by thermomagnetometry, with respect to structural crystallisation, determined by scanning calorimetry, which was correlated with magnetic hyperfine field, determined by transmission Mössbauer spectroscopy.

  4. Predicting the properties of the lead alloys from DFT calculations

    International Nuclear Information System (INIS)

    We provide qualitative results for the physical properties of the lead alloys at atomic scale by using DFT calculations. Our approach is based on the two assumptions: (i) the geometric structure of lead atoms provides a matrix where the alloying elements can take their positions in the structure as substitutions and (ii) there is a small probability of a direct interaction between the alloying elements, thus the interactions of each alloying element may be approximated by the interactions to the lead matrix. DFT calculations are used to investigate the interaction between several types of impurities and the lead matrix for low concentrations of the alloying element. We report results such as the enthalpy of formation, charge transfer and mechanical stress induced by the impurities in the lead matrix; these results can be used as qualitative guide in tuning the physico-chemical properties of the lead alloys

  5. Predicting the properties of the lead alloys from DFT calculations

    Energy Technology Data Exchange (ETDEWEB)

    Buimaga-Iarinca, L., E-mail: luiza.iarinca@itim-cj.ro; Calborean, A. [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca (Romania)

    2015-12-23

    We provide qualitative results for the physical properties of the lead alloys at atomic scale by using DFT calculations. Our approach is based on the two assumptions: (i) the geometric structure of lead atoms provides a matrix where the alloying elements can take their positions in the structure as substitutions and (ii) there is a small probability of a direct interaction between the alloying elements, thus the interactions of each alloying element may be approximated by the interactions to the lead matrix. DFT calculations are used to investigate the interaction between several types of impurities and the lead matrix for low concentrations of the alloying element. We report results such as the enthalpy of formation, charge transfer and mechanical stress induced by the impurities in the lead matrix; these results can be used as qualitative guide in tuning the physico-chemical properties of the lead alloys.

  6. Formation and reversion of strain induced martensite on Fe-Cr-Ni alloys Formação e reversão da martensita em ligas ferro-cromo-níquel

    Directory of Open Access Journals (Sweden)

    Gabriela Lujan Brollo

    2013-06-01

    Full Text Available Austenitic stainless steels represent a significant portion of the alloys used in the aeronautical, chemical, shipbuilding, food processing and biomechanical industries. They combine good mechanical properties with high corrosion resistance. When subjected to cold deformation, these steels exhibit a metastable phase called: strain induced martensite (ferromagnetic, whose formation increases mechanical strength and formability, allowing for a wide range of applications. Heated from room temperature, the strain induced martensite transforms to austenite (non-magnetic. It is easy to find information in literature about the strain induced martensite for 18Cr/8Ni austenitic steels, but there is no data for high nickel alloys like A286 (26Ni, 15Cr, Incoloy 800 (30-40 Ni, 21Cr and Inconel (50Ni, 19Cr. Therefore, this study aimed to verify the formation of strain induced martensite after cold working in Fe-18Cr base alloys with the addition of up to 60 %Ni. The reversion of this phase to austenite after annealing up to 600 ºC was also studied. Optical microscopy, magnetic characterization tests, and x-ray diffraction were used to analyze the transformations.Os aços inoxidáveis austeníticos são materiais de alto valor agregado, representando uma parcela importante das ligas usadas, principalmente, nas indústrias aeronáutica, química, naval, alimentícia e biomecânica. Apresentam boas propriedades mecânicas aliadas à elevada resistência à corrosão. Quando submetido à deformação a frio, esses aços exibem uma fase metaestável denominada martensita induzida por deformação (ferromagnética, cuja formação aumenta a resistência mecânica e conformabilidade, permitindo sua ampla gama de aplicações. Aquecida acima da temperatura ambiente, a martensita induzida por deformação se transforma em austenita. Existem dados na literatura sobre a formação da martensita induzida por deformação em aços austeníticos 18Cr/8Ni, mas não h

  7. 激光诱导Cu合金等离子体光谱特性实验研究%Experimental investigation on the properties of laser induced plasma spectroscopy of cuprum alloy

    Institute of Scientific and Technical Information of China (English)

    董少龙; 董开虎; 张金平; 李旭; 郭庆林

    2012-01-01

    Laser induced plasma of cuprum alloy was excited by Nd: YAG laser. Temporal characteristic of spectroscopy and influence that different ambient atmospheres worked to the intensity of spectroscopy were systemic investigated. The experimental result suggests that the choice of time to acquire the best spectrum is hardly related to ambient atmosphere, the melting point and boiling point of elements, it rests with the excitation potential of the spectral line; Compared with air, argon and mixture consisted of helium and argon makes the intensity of laser induced plasma spectroscopy increased significantly.%采用调Q Nd:YAG激光器激发诱导Cu合金的等离子体,系统研究了等离子体光谱强度随时间演化特性,并探究了不同环境气氛对激光诱导等离子体光谱强度的影响.实验结果表明:信噪比最佳的延时选择与分析光谱线激发电位密切相关,而受环境气氛、分析元素的熔点、沸点影响不大;氩气和氦-氩混合气体环境与空气环境相比,激光诱导等离子体光谱强度明显增强.

  8. 某履带式自行火炮铝合金诱导轮有限元分析%Finite Element Analysis of Aluminium Alloy Inducer of a Crawler-type Self- propelled Gun

    Institute of Scientific and Technical Information of China (English)

    石强; 潘玉田; 方东旭

    2014-01-01

    以国防科技工业精密塑性成形技术研究应用中心为某履带式自行火炮设计制造的用于替换旧式钢制结构的7A04型铝合金诱导轮为例,使用UG NX软件建立几何模型,将其导入ANSYS Workbench建立有限元模型,按工况约束加载,系统地计算和分析了其应力应变分布规律、变形量、疲劳特性等。结果表明,7A04型铝合金诱导轮完全满足设计和实际工作要求,为工程试验、结构改进、优化设计和应用拓展等提供了理论依据。%Taking precision plastic forming technology and industry for national defense technology research center for the de-sign and fabrication of a crawler self-propelled guns used to replace the old steel structure induced type of 7 a04 aluminum alloy wheel for an example, establishing geometric model by using UG NX software, importing into ANSYS Workbench to build finite element model; according to the working condition of constraint load, systematically calculation and analysis the stress and strain distribution rule, the deformation and fatigue characteristics. The results showed that the type of 7 a04 alu-minum alloy idler completely meet the requirements of design and practical work, and at the same time provided theoretical basis for engineering test, structural improvement, optimization design and application development.

  9. Corrosion of alloy 22 in phosphate and chloride containing solutions

    International Nuclear Information System (INIS)

    Alloy C-22 is a Ni-based alloy (22% Cr, 13% Mo, 3% W y 3% Fe in weight per cent) that exhibits an excellent uniform and localized corrosion resistance due to its protective passive film. It was designed to resist the most aggressive environments for industrial applications. Alloy 22 is one of the candidates to be considered for the outer shell of the canister that would contain high level radioactive nuclear wastes. The effect of phosphate ion in chloride containing solutions at 90 C degrees was studied under aggressive conditions were this material might be susceptible to crevice corrosion. The electrolyte solution, which consisted of 1M NaCl and different phosphate concentrations (between 10-3M and 1M), was deoxygenated by bubbling with nitrogen. Electrochemical tests, electron microscope observations (SEM) and energy dispersive spectrometer analysis (EDS) were conducted. Crevice corrosion was not detected and the comparison of the potentiodynamic polarization tests showed an increase of the passivity range in phosphate containing solutions. The passive current value was 1 μA/cm2 approximately in all the tests that were performed in this work. The differences in composition of the anodic film formed on the samples suggest that phosphate is responsible for the increase of the passivity range by incorporation to the passive film. (author)

  10. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. 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.

  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. A clinical isolate of Candida albicans with mutations in ERG11 (encoding sterol 14alpha-demethylase) and ERG5 (encoding C22 desaturase) is cross resistant to azoles and amphotericin B.

    Science.gov (United States)

    Martel, Claire M; Parker, Josie E; Bader, Oliver; Weig, Michael; Gross, Uwe; Warrilow, Andrew G S; Kelly, Diane E; Kelly, Steven L

    2010-09-01

    A clinical isolate of Candida albicans was identified as an erg5 (encoding sterol C22 desaturase) mutant in which ergosterol was not detectable and ergosta 5,7-dienol comprised >80% of the total sterol fraction. The mutant isolate (CA108) was resistant to fluconazole, voriconazole, itraconazole, ketoconazole, and clotrimazole (MIC values, 64, 8, 2, 1, and 2 microg ml(-1), respectively); azole resistance could not be fully explained by the activity of multidrug resistance pumps. When susceptibility tests were performed in the presence of a multidrug efflux inhibitor (tacrolimus; FK506), CA108 remained resistant to azole concentrations higher than suggested clinical breakpoints for C. albicans (efflux-inhibited MIC values, 16 and 4 microg ml(-1) for fluconazole and voriconazole, respectively). Gene sequencing revealed that CA108 was an erg11 erg5 double mutant harboring a single amino acid substitution (A114S) in sterol 14alpha-demethylase (Erg11p) and sequence repetition (10 duplicated amino acids), which nullified C22 desaturase (Erg5p) function. Owing to a lack of ergosterol, CA108 was also resistant to amphotericin B (MIC, 2 microg ml(-1)). This constitutes the first report of a C. albicans erg5 mutant isolated from the clinic. PMID:20547793

  14. Nanoprecipitation in a beta-titanium alloy

    International Nuclear Information System (INIS)

    Highlights: • In-situ SANS has been applied to study precipitation in β -Ti alloy. • Rate of precipitation is far more rapid in the cold-rolled alloy than non cold-rolled. • The rapid precipitation dramatically improves the alloy hardness. • Extensive ω phase is present after 400 °C/16 h heat-treatment. • SANS modelling and TEM-EDX shows the precipitates are Ti rich. - Abstract: This paper represents the first application of small angle neutron scattering (SANS) to the study of precipitate nucleation and growth in β-Ti alloys in an attempt to observe both the precipitation process in-situ and to quantify the evolving microstructure that affects mechanical behaviour. TEM suggests that athermal ω can be induced by cold-rolling Gum metal, a β-Ti alloy. During thermal exposure at 400°C, isothermal ω particles precipitate at a greater rate in cold-rolled material than in the recovered, hot deformed state. SANS modelling is consistent with disc shaped nanoparticles, with length and radius under 6nm after thermal exposures up to 16h. Modelling suggests that the nanoprecipitate volume fraction and extent of Nb partitioning to the β matrix is greater in the cold-rolled material than the extruded. The results show that nucleation and growth of the nanoprecipitates impart strengthening to the alloy

  15. Nanoprecipitation in a beta-titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Coakley, James, E-mail: j.coakley06@imperial.ac.uk [Department of Materials, Imperial College, South Kensington, London SW7 2AZ, England (United Kingdom); Vorontsov, Vassili A. [Department of Materials, Imperial College, South Kensington, London SW7 2AZ, England (United Kingdom); Littrell, Kenneth C. [Oak Ridge National Laboratory, Chemical and Engineering Materials Division, Oak Ridge, TN 37831 (United States); Heenan, Richard K. [Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX, England (United Kingdom); Ohnuma, Masato [Laboratory of Quantum Beam System Engineering, Hokkaido University, Sapporo 060-0808 (Japan); Jones, Nicholas G. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, England (United Kingdom); Dye, David [Department of Materials, Imperial College, South Kensington, London SW7 2AZ, England (United Kingdom)

    2015-02-25

    Highlights: • In-situ SANS has been applied to study precipitation in β -Ti alloy. • Rate of precipitation is far more rapid in the cold-rolled alloy than non cold-rolled. • The rapid precipitation dramatically improves the alloy hardness. • Extensive ω phase is present after 400 °C/16 h heat-treatment. • SANS modelling and TEM-EDX shows the precipitates are Ti rich. - Abstract: This paper represents the first application of small angle neutron scattering (SANS) to the study of precipitate nucleation and growth in β-Ti alloys in an attempt to observe both the precipitation process in-situ and to quantify the evolving microstructure that affects mechanical behaviour. TEM suggests that athermal ω can be induced by cold-rolling Gum metal, a β-Ti alloy. During thermal exposure at 400°C, isothermal ω particles precipitate at a greater rate in cold-rolled material than in the recovered, hot deformed state. SANS modelling is consistent with disc shaped nanoparticles, with length and radius under 6nm after thermal exposures up to 16h. Modelling suggests that the nanoprecipitate volume fraction and extent of Nb partitioning to the β matrix is greater in the cold-rolled material than the extruded. The results show that nucleation and growth of the nanoprecipitates impart strengthening to the alloy.

  16. The DynAlloy Visualizer

    OpenAIRE

    Bendersky, Pablo; Galeotti, Juan Pablo; Garbervetsky, Diego

    2014-01-01

    We present an extension to the DynAlloy tool to navigate DynAlloy counterexamples: the DynAlloy Visualizer. The user interface mimics the functionality of a programming language debugger. Without this tool, a DynAlloy user is forced to deal with the internals of the Alloy intermediate representation in order to debug a flaw in her model.

  17. Na2CO3―induced Gas Evolution Reaction and Morphology Modulation on Magnesium Alloy during Micro―arc Oxidation

    Directory of Open Access Journals (Sweden)

    WANG Xiao-Bo, TIAN Xiu-Bo, GONG Chun-Zhi, YANG Shi-Qin

    2011-07-01

    Full Text Available Surface morphology of the ceramic coatings can be modulated by gas evolution on anodes during micro arc oxidation (MAO) processes. A novel technique to enhance gas evolution using Na2CO3―containing solution was proposed. MAO ceramic coatings were fabricated on AZ31 magnesium alloy using Na2CO3 as a special additive in Na3PO4+KOH +NaF base electrolyte. The effects of Na2CO3 addition on the reaction of gas evolution near the anode, morphology modulation and chemical composition were investigated by using GC―MS, SEM, XRD and FTIR, respectively. The results show that both O2 and CO2 are evolved from the anode with Na2CO3 addition during MAO process. MgCO3 is found in the coating during the anodic oxidation before MAO, while only MgO is detected in the coating after MAO process. It is attributed to the decomposition of MgCO3 to MgO and CO2 due to local high temperature. Na2CO3 addition has slight effect on the microstructure of the coating and MgO is the main phase no matter whether Na2CO3 is utilized. With the addition of Na2CO3 the number of larger―size pores decreases and porosity in the coatings increases.

  18. Microstructure and Wear Behaviour of Laser-induced Thermite Reaction Al2O3 Ceramic Coating on AA7075 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    Kaijin HUANG; Xin LIN; Changsheng XIE; T.M. Yue

    2007-01-01

    The microstructure and wear behaviour of the thermite reaction coating produced by the hybrid laser claddingremelting on AA7075 aluminum alloy for the systems of Al-CuO-SiO2, Al-Cr2O3-SiO2, Al-Fe2O3-SiO2, and Al-TiO2-SiO2 were studied. The results of the X-ray diffraction (XRD) analysis show that in all the four reaction coatings, α-Al2O3 and γ-Al2O3 phases were present at the top surface, together with various intermetallic phases, the corresponding reduced metal and Al phase in the fusion zone. Under the dry sliding condition, the wear resistance, in terms of weight loss, of the laser-clad specimens was considerably higher than that of the untreated specimen. The predominant wear mechanism of the former specimens was abrasive wear, while for the latter, it was the adhesive wear that prevailed.

  19. Low-Energy Amorphization of Ti1Sb2Te5 Phase Change Alloy Induced by TiTe2 Nano-Lamellae

    Science.gov (United States)

    Ding, Keyuan; Rao, Feng; Lv, Shilong; Cheng, Yan; Wu, Liangcai; Song, Zhitang

    2016-07-01

    Increasing SET operation speed and reducing RESET operation energy have always been the innovation direction of phase change memory (PCM) technology. Here, we demonstrate that ∼87% and ∼42% reductions of RESET operation energy can be achieved on PCM cell based on stoichiometric Ti1Sb2Te5 alloy, compared with Ge2Sb2Te5 and non-stoichiometric Ti0.4Sb2Te3 based PCM cells at the same size, respectively. The Ti1Sb2Te5 based PCM cell also shows one order of magnitude faster SET operation speed compared to that of the Ge2Sb2Te5 based one. The enhancements may be caused by substantially increased concentration of TiTe2 nano-lamellae in crystalline Ti1Sb2Te5 phase. The highly electrical conduction and lowly thermal dissipation of the TiTe2 nano-lamellae play a major role in enhancing the thermal efficiency of the amorphization, prompting the low-energy RESET operation. Our work may inspire the interests to more thorough understanding and tailoring of the nature of the (TiTe2)n(Sb2Te3)m pseudobinary system which will be advantageous to realize high-speed and low-energy PCM applications.

  20. Low-Energy Amorphization of Ti1Sb2Te5 Phase Change Alloy Induced by TiTe2 Nano-Lamellae

    Science.gov (United States)

    Ding, Keyuan; Rao, Feng; Lv, Shilong; Cheng, Yan; Wu, Liangcai; Song, Zhitang

    2016-01-01

    Increasing SET operation speed and reducing RESET operation energy have always been the innovation direction of phase change memory (PCM) technology. Here, we demonstrate that ∼87% and ∼42% reductions of RESET operation energy can be achieved on PCM cell based on stoichiometric Ti1Sb2Te5 alloy, compared with Ge2Sb2Te5 and non-stoichiometric Ti0.4Sb2Te3 based PCM cells at the same size, respectively. The Ti1Sb2Te5 based PCM cell also shows one order of magnitude faster SET operation speed compared to that of the Ge2Sb2Te5 based one. The enhancements may be caused by substantially increased concentration of TiTe2 nano-lamellae in crystalline Ti1Sb2Te5 phase. The highly electrical conduction and lowly thermal dissipation of the TiTe2 nano-lamellae play a major role in enhancing the thermal efficiency of the amorphization, prompting the low-energy RESET operation. Our work may inspire the interests to more thorough understanding and tailoring of the nature of the (TiTe2)n(Sb2Te3)m pseudobinary system which will be advantageous to realize high-speed and low-energy PCM applications. PMID:27469931

  1. Kinetics behaviour of metastable equiatomic Cu–Fe solid solution as function of the number of collisions induced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Contini, A., E-mail: alessandro.contini@hotmail.com [Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari, via Vienna 2, 07100 Sassari (Italy); Delogu, F. [Dipartimento di Ingegneria Meccanica, Chimica, e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari (Italy); Garroni, S.; Mulas, G.; Enzo, S. [Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari, via Vienna 2, 07100 Sassari (Italy)

    2014-12-05

    Graphical abstract: - Highlights: • Cu–Fe powders were studied as a function of the number of hits during MA. • An impulsive model describes the kinetics curves of solid solution formation. • The kinetic curve indicates that powders must undergo 6 critical events to transform. - Abstract: We have addressed a new study by mechanical alloying on the nominally immiscible Cu{sub 50}Fe{sub 50} system with the aim of relating the solid state transformation process, with formation of a disordered unstable solid solution having the face centered cubic habit, to parameters reflecting the impulsive, discontinuous nature of the process. The milling set-up, tools and powder were adjusted in order to ensure completely anelastic hits. Phase analysis, structure and microstructure parameters of such powder system have been followed accurately in the course of the kinetics by X-ray Diffraction using the Rietveld method. The experimental kinetics data points of the amount of transformed solid solution show a typical sigmoidal behavior. It was assumed that dissolution only occurs in the volumes of material that have undergone the necessary critical loading conditions, which is accounted by a discrete series expansion. The mass fraction effectively processed at each collision can be regarded as an apparent rate constant for the microstructural refinement and phase transformation processes. Analysis of model curves fitting the experimental data suggests that it takes up an average of 6 impacts of coupled powder particles to drive the system to the new unstable nano-crystalline state.

  2. A jumping shape memory alloy under heat

    Science.gov (United States)

    Yang, Shuiyuan; Omori, Toshihiro; Wang, Cuiping; Liu, Yong; Nagasako, Makoto; Ruan, Jingjing; Kainuma, Ryosuke; Ishida, Kiyohito; Liu, Xingjun

    2016-02-01

    Shape memory alloys are typical temperature-sensitive metallic functional materials due to superelasticity and shape recovery characteristics. The conventional shape memory effect involves the formation and deformation of thermally induced martensite and its reverse transformation. The shape recovery process usually takes place over a temperature range, showing relatively low temperature-sensitivity. Here we report novel Cu-Al-Fe-Mn shape memory alloys. Their stress-strain and shape recovery behaviors are clearly different from the conventional shape memory alloys. In this study, although the Cu-12.2Al-4.3Fe-6.6Mn and Cu-12.9Al-3.8Fe-5.6Mn alloys possess predominantly L21 parent before deformation, the 2H martensite stress-induced from L21 parent could be retained after unloading. Furthermore, their shape recovery response is extremely temperature-sensitive, in which a giant residual strain of about 9% recovers instantly and completely during heating. At the same time, the phenomenon of the jumping of the sample occurs. It is originated from the instantaneous completion of the reverse transformation of the stabilized 2H martensite. This novel Cu-Al-Fe-Mn shape memory alloys have great potentials as new temperature-sensitive functional materials.

  3. Thermal cycling behavior of as-quenched and aged Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Geng, H.; He, S.; Lei, T. [Harbin Inst. of Tech. (China). School of Materials Science and Engineering

    1997-09-01

    Thermal cycling tests between 77 and 623 K were performed on Ti-6Al-4V alloy; the tensile properties were evaluated, and transmission electron microscopy (TEM) microstructural analysis was performed both before and after thermal cycling. Thermal cycling (1,000 cycles) promptly increases the strength of the as-quenched alloy, induces a slight decrease in strength for the near-peak-aged alloy, and makes no change for that of the overaged alloy. The elongation of the alloy in all heat-treated conditions decreases after 1,000 thermal cycles. The loss of fracture elongation of the as-quenched alloy is the largest, but the residual ductility is the highest. The loss of fracture elongation for the near-peak-aged alloy is lower, and the residual plasticity is higher than those for the overaged alloy.

  4. Temperature dependence of the magnetostriction and the induced anisotropy in nanocrystalline FeCuNbSiB alloys, and their fluxgate properties

    DEFF Research Database (Denmark)

    Nielsen, Otto V; Petersen, Jan Raagaard

    1994-01-01

    Making use of the stress induced magnetic anisotropy in some iron-rich FeCuNbSiB nanocrystalline materials we studied the thermal dependence of their magnetostriction which becomes zero below the Curie temperature. The choice of a suitable composition and annealing temperature results in materials...

  5. Atom probe study of the microstructural evolution induced by irradiation in Fe-Cu ferritic alloys and pressure vessel steels; Etude a la sonde atomique de l`evolution microstructurale sous irradiation d`alliages ferritiques Fe-Cu et d`aciers de cuve REP

    Energy Technology Data Exchange (ETDEWEB)

    Pareige, P.

    1996-04-01

    Pressure vessel steels used in pressurized water reactors are low alloyed ferritic steels. They may be prone to hardening and embrittlement under neutron irradiation. The changes in mechanical properties are generally supposed to result from the formation of point defects, dislocation loops, voids and/or copper rich clusters. However, the real nature of the irradiation induced-damage in these steels has not been clearly identified yet. In order to improve our vision of this damage, we have characterized the microstructure of several steels and model alloys irradiated with electrons and neutrons. The study was performed with conventional and tomographic atom probes. The well known importance of the effects of copper upon pressure vessel steel embrittlement has led us to study Fe-Cu binary alloys. We have considered chemical aging as well as aging under electron and neutron irradiations. The resulting effects depend on whether electron or neutron irradiations ar used for thus. We carried out both kinds of irradiation concurrently so as to compare their effects. We have more particularly considered alloys with a low copper supersaturation representative of that met with the French vessel alloys (0.1% Cu). Then, we have examined steels used on French nuclear reactor pressure vessels. To characterize the microstructure of CHOOZ A steel and its evolution when exposed to neutrons, we have studied samples from the reactor surveillance program. The results achieved, especially the characterization of neutron-induced defects have been compared with those for another steel from the surveillance program of Dampierre 2. All the experiment results obtained on model and industrial steels have allowed us to consider an explanation of the way how the defects appear and grow, and to propose reasons for their influence upon steel embrittlement. (author). 3 appends.

  6. Rheological properties and microstructure of the alloy AA 6063 obtained by semisolid processing using magnetohydrodynamic agitation and activated fusion induced by stress (SIMA process)

    International Nuclear Information System (INIS)

    The rheological behavior and the microstructural evolution of the alloy AA6063 submitted to two different processes, cold deformation and partial fusion, SIMA process and magnetohydrodynamic agitation during solidification, are studied. The evolution of the microstructure during the isothermal maintenance was studied in order to verify if the classic Ostwald ripening, growth and coalescence mechanisms are applicable to alloys made by these processes. The rheological properties were evaluated using a compression rheometer between parallel plates with data on time and position collected digitally. The procedure included the full metallographic characterization of the samples for SIMA and MHD processes as well as the study of the microstructural evolution during isothermal maintenance at various solid fractions. Compression tests were performed of short cylinders extracted from cast ingots with a dendritic microstructure, cold deformed material and obtained by the MHD process. These test pieces were tested at different solid fractions under constant load, to determine the equation that governs the rheological behavior of the material in semisolid state, according to two parameters of the Ostwald-de-Waele power law. Based on the results obtained, the morphology of the primary phase in the microstructure is deduced to be highly relevant to its rheological behavior. A globular microstructure has the typical behavior of a fluid when it is formed in a semi-solid state, but this does not hold true for a cast dendritic microstructure. The mechanisms that operate in the microstructural evolution during the isothermal maintenance were proven by metallographic analysis. The differences in rheological behavior are possibly due to the morphological differences of the AlFeSI intermetallics. These intermetallics are located in the inter dendritic zones and prepare the formation of the incipient liquid phase and the effective amount of liquid that participates in the deformation

  7. Superplasticity in titanium alloys

    OpenAIRE

    J. Sieniawski; Motyka, M.

    2007-01-01

    Purpose: The paper reports characteristic of superplasticity phenomenon in titanium alloys and possibility of its applications.Design/methodology/approach: The main objective of the paper is to show features of superplastic forming of titanium alloys and current research trends aiming at widespread application of this technology.Findings: In the paper characteristic of selected superplastic titanium alloys was presented. The effect of microstructural parameters on superplasticity was consider...

  8. Corrosion resistant amorphous alloys

    International Nuclear Information System (INIS)

    A review of publication data on corrosion resistance of amorphous alloys and the methods of amorphization of surface layers of massive materials (laser treatment, iron implantation, detonation-gas spraying, cathode and ion sputtering, electrodeposition) was made. A study was made on corrosion properties of Fe66Cr11B10Si4 alloy in cast state and after laser irradiation, rendering the surface amorphous as well as the samples of Arenco iron and steel 20 with ion-plasma coatings of Fe-Cr-Ni-Ti alloy. It was established that amorphous coatings posses much higher corrosion resistance as compared to crystalline alloys on the same base

  9. A Laser Induced Breakdown Spectroscopy application based on Local Thermodynamic Equilibrium assumption for the elemental analysis of alexandrite gemstone and copper-based alloys

    Science.gov (United States)

    De Giacomo, A.; Dell'Aglio, M.; Gaudiuso, R.; Santagata, A.; Senesi, G. S.; Rossi, M.; Ghiara, M. R.; Capitelli, F.; De Pascale, O.

    2012-04-01

    Laser Induced Breakdown Spectroscopy (LIBS) is an appealing technique to study laser-induced plasmas (LIPs), both from the basic diagnostics point of view and for analytical applications. LIPs are complex dynamic systems, expanding at supersonic velocities and undergoing a transition between different plasma regimes. If the Local Thermodynamic Equilibrium (LTE) condition is valid for such plasmas, several analytical methods can be employed and fast quantitative analyses can be performed on a variety of samples. In the present paper, a discussion about LTE is carried out and an innovative application to the analysis of the alexandrite gemstone is presented. In addition, a study about the influence of plasma parameters on the performance of LTE-based methods is reported for bronze and brass targets.

  10. High-strength iron aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.; Maziasz, P.J.

    1996-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile ductility due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications despite their excellent corrosion properties. With regard to the ductility problem, alloy development efforts have produced significant improvements, with ductilities of 10-20% and tensile yield strengths as high as 500 MPa being reported. Likewise, initial improvements in creep resistance have been realized through small additions of Mo, Nb, and Zr.

  11. Cleavage crystallography of liquid metal embrittled aluminum alloys

    Science.gov (United States)

    Reynolds, A. P.; Stoner, G. E.

    1991-01-01

    The crystallography of liquid metal-induced transgranular cleavage in six aluminum alloys having a variety of microstructures has been determined via Laue X-ray back reflection. The cleavage crystallography was independent of alloy microstructure, and the cleavage plane was 100-plane oriented in all cases. It was further determined that the cleavage crystallography was not influenced by alloy texture. Examination of the fracture surface indicated that there was not a unique direction of crack propagation. In addition, the existence of 100-plane cleavage on alloy 2024 fracture surfaces was inferred by comparison of secondary cleavage crack intersection geometry on the 2024 surfaces with the geometry of secondary cleavage crack intersections on the test alloys.

  12. Degassing of molten alloys with the assistance of ultrasonic vibration

    Science.gov (United States)

    Han, Qingyou; Xu, Hanbing; Meek, Thomas T.

    2010-03-23

    An apparatus and method are disclosed in which ultrasonic vibration is used to assist the degassing of molten metals or metal alloys thereby reducing gas content in the molten metals or alloys. High-intensity ultrasonic vibration is applied to a radiator that creates cavitation bubbles, induces acoustic streaming in the melt, and breaks up purge gas (e.g., argon or nitrogen) which is intentionally introduced in a small amount into the melt in order to collect the cavitation bubbles and to make the cavitation bubbles survive in the melt. The molten metal or alloy in one version of the invention is an aluminum alloy. The ultrasonic vibrations create cavitation bubbles and break up the large purge gas bubbles into small bubbles and disperse the bubbles in the molten metal or alloy more uniformly, resulting in a fast and clean degassing.

  13. Oxidization-Induced Tin Whisker Growth on the Surface of Sn-3.8Ag-0.7Cu-1.0Er Alloy

    Science.gov (United States)

    Hao, Hu; Shi, Yaowu; Xia, Zhidong; Lei, Yongping; Guo, Fu

    2009-08-01

    Rapid tin whisker growth has been found in Sn-3.8Ag-0.7Cu1.0Er solder joints. The morphology of the tin whiskers changes from rodlike to threadlike when the storage temperature increases from 25 °C to 150 °C. The compressive stress induced by the lattice expansion of the oxidized ErSn3 phase provides the driving force and the tin atoms released from the oxidization of the ErSn3 phase provide the material source for the tin whisker growth.

  14. Excitation of a hydrogen subsystem in metals and alloys under ionizing irradiation. 2. Model of radiation-induced diffusion mechanism and hydrogen emerging from metals

    International Nuclear Information System (INIS)

    A consideration is given to a non-equilibrium radiation-induced diffusion model as well as a model of hydrogen and its isotope emerging from metals under ionizing irradiation. It is assumed that the hydrogen emerging under irradiation is associated with the excitation of nonequilibrium vibrational states in a hydrogen subsystem of metals and with reducing surface potential barrier of desorbed molecules. Among other things the coefficient of deuterium diffusion in palladium is shown to increase by a factor of 30 under irradiation compared to that of a nonirradiated specimen

  15. Thermofluency in zirconium alloys

    International Nuclear Information System (INIS)

    A summary is presented about the theoretical and experimental results obtained at present in thermofluency under radiation in zirconium alloys. The phenomenon of thermofluency is presented in a general form, underlining the thermofluency at high temperature because this phenomenon is similar to the thermofluency under radiation, which ocurrs in zirconium alloys into the operating reactor. (author)

  16. High temperature niobium alloys

    International Nuclear Information System (INIS)

    Niobium alloys are currently being used in various high temperature applications such as rocket propulsion, turbine engines and lighting systems. This paper presents an overview of the various commercial niobium alloys, including basic manufacturing processes, properties and applications. Current activities for new applications include powder metallurgy, coating development and fabrication of advanced porous structures for lithium cooled heat pipes

  17. 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.

  18. Alloys in energy development

    International Nuclear Information System (INIS)

    The development of new and advanced energy systems often requires the tailoring of new alloys or alloy combinations to meet the novel and often stringent requirements of those systems. Longer life at higher temperatures and stresses in aggressive environments is the most common goal. Alloy theory helps in achieving this goal by suggesting uses of multiphase systems and intermediate phases, where solid solutions were traditionally used. However, the use of materials under non-equilibrium conditions is now quite common - as with rapidly solidified metals - and the application of alloy theory must be modified accordingly. Under certain conditions, as in a reactor core, the rate of approach to equilibrium will be modified; sometimes a quasi-equilibrium is established. Thus an alloy may exhibit enhanced general diffusion at the same time as precipitate particles are being dispersed and solute atoms are being carried to vacancy sinks. We are approaching an understanding of these processes and can begin to model these complex systems

  19. Low temperature irradiation effects on iron boron based amorphous metallic alloys

    International Nuclear Information System (INIS)

    Three Fe-B amorphous alloys (Fe80B20, Fe27Mo2B20 and Fe75B25) and the crystallized Fe3B alloy have been irradiated at the temperature of liquid hydrogen. Electron irradiation and irradiation by 10B fission fragments induce point defects in amorphous alloys. These defects are characterized by an intrinsic resistivity and a formation volume. The threshold energy for the displacement of iron atoms has also been calculated. Irradiation by 235U fission fragments induces some important structural modifications in the amorphous alloys

  20. Brazing with plated alloys

    International Nuclear Information System (INIS)

    The use of braze alloy preforms on complex geometry components is at times a very difficult task requiring extensive handling of the parts or even tack welding of the preform to ensure that it is held in place. One method of overcoming these difficulties is the use of plated braze alloys (i.e., filler metals) applied directly to the braze region. Plating helps to avoid the potential for contamination resulting from handling and also ensures that the braze alloy is located properly. Examples are discussed in which an electroplated silver-copper alloy is used as an alternative to the BAg8 preforms and electroless nickel is used as a replacement for an amorphous Ni-P braze alloy foil. A toroidal cooling plate with helical flow channels was fabricated from oxygen-free high conductivity (OFHC) and brazed using the electroplated silver-copper alloy. The silver-copper braze alloy was applied to the copper substrate in a laminated fashion of alternating layers of silver and copper, which in combination approximated the eutectic composition (72% Ag-28% Cu by weight). Examination of the brazed assemblies indicated that in both cases the advantages of using plated braze alloys are numerous. These advantages include decreased labor, improved cleanliness and exactness of braze alloy placement. The primary disadvantage was an increased tendency for solidification defects presumably resulting from contaminants in the plating baths. This last observation is presently being examined in greater detail. The end results is that the assemblies brazed with the plated alloys were acceptable for the intended application and that the use of plating facilitated the successful assembly of these components

  1. Study on irradiation-induced magnetic transition in FeRh alloys by means of Fe K-edge XMCD spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)]. E-mail: iwase@mtr.osakafu-u.ac.jp; Fukuzumi, M. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Zushi, Y. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Suzuki, M. [Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198 (Japan); Takagaki, M. [Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198 (Japan); Kawamura, N. [Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198 (Japan); Chimi, Y. [Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Ishikawa, N. [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195 (Japan); Mizuki, J. [Synchrotron Radiation Research Center, Japan Atomic Energy Agency, Sayo, Hyogo 679-5148 (Japan); Ono, F. [Department of Physics, Okayama University, Okayama 700-8530 (Japan)

    2007-03-15

    We have studied the effects of swift heavy ion irradiation on the magnetic properties of Fe-50at.%Rh intermetallic compound by using Fe K-edge X-ray magnetic circular dichroism (XMCD) at 20 K. For an unirradiated specimen, no signal of XMCD spectrum has been observed because Fe-50at.%Rh intermetallic compound is intrinsically anti-ferromagnetic below room temperature. For the specimens irradiated with 120-200 MeV Ni, Kr, Xe or Au ions, we have found XMCD spectra which are characterized by a dispersion-type profile with a positive peak and a negative peak near Fe K-edge. The intensity of XMCD spectra remarkably depends on ion-fluence and ion-mass. The experimental result implies that the ferromagnetic state is induced by the swift heavy ion irradiation. The change in magnetic state of Fe element is discussed in terms of energy deposition through the elastic and electronic processes.

  2. Femtosecond laser-induced phase transformations in amorphous Cu{sub 77}Ni{sub 6}Sn{sub 10}P{sub 7} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Zou, G.; Wu, A.; Bai, H. [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liu, L., E-mail: liulei@tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); The State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Chen, N. [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhou, Y. [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2015-01-14

    In this study, the femtosecond laser-induced crystallization of CuNiSnP amorphous ribbons was investigated by utilizing an amplified Ti:sapphire laser system. X-ray diffraction and scanning electronic microscope were applied to examine the phase and morphology changes of the amorphous ribbons. Micromachining without crystallization, surface patterning, and selective crystallization were successfully achieved by changing laser parameters. Obvious crystallization occurred under the condition that the laser fluence was smaller than the ablation threshold, indicating that the structural evolution of the material depends strongly on the laser parameters. Back cooling method was used to inhibit heat accumulation; a reversible transformation between the disordered amorphous and crystalline phases can be achieved by using this method.

  3. Contribution to depth profiling by particle induced X-ray emission application to the study of zinc diffusion in AgZn alloy

    International Nuclear Information System (INIS)

    A contribution of the study of the capacities of Particle Induced X-ray Emission (P.I.X.E.) for depth profiling, in the range of 1 to 10 micrometers and over, is presented here. It is shown that, in a non destructuve way, the concentration profile of a given element can be obtained, in principle, by deconvoluting the X-ray yields of this element, measured in a set of experiments in which the energy of the impinging protons, hence their range, is systematically varied. Direct deconvolution procedure, which leads to the inversion of an ill-conditionned matrix is unsuitable. So we generalized the iterative procedure previously used by Vegh to solve a similar problem. Alternatively we also used a fitting procedure of several parameters which gave us somewhat better than those of the iterative procedure. Both algorithms where applied to a set of X-ray yields induced by protons of energy between 0.45 to 2 MeV, corresponding to the first 6 micrometers of various depletion profiles of zinc in an initially homogeneous Ag-3 at % Zn annealed under vacuum. For investigation of deeper layers, a sectionning technique which consists in analysing thin film hydroxide targets by specific chemistry of tiny turning, was developped with success. Cross-reference of all the obtained profiles was made with electron microprobe determination on transverse section, and with the predictions of the theory of atomic diffusion. In addition, the possibilities of increasing the depth resolution by developping techniques either of controled sanding of the surface, or analysis of the sample is discussed

  4. Crystallographic orientation-spray formed hypereutectic aluminium-silicon alloys

    Directory of Open Access Journals (Sweden)

    Hamilta de Oliveira Santos

    2005-06-01

    Full Text Available Aluminium-silicon alloys have been wide accepted in the automotive, electric and aerospace industries. Preferred orientation is a very common condition for metals and alloys. Particularly, aluminium induces texture during the forming process. The preparation of an aggregate with completely random crystal orientation is a difficult task. The present work was undertaken to analyse the texture by X-ray diffraction techniques, of three spray formed hypereutectic Al-Si alloys. Samples were taken from a billet of an experimental alloy (alloy 1 and were subsequently hot-rolled and cold-rolled (height reduction, 72% and 70%, respectively. The other used samples, alloys 2 and 3, were taken from cylinders liners. The results from the Laue camera showed texture just in the axial direction of alloy 3. The pole figures also indicated the presence of a typical low intensity deformation texture, especially for alloy 3. The spray formed microstructure, which is very fine, hinders the Al-Si texture formation during mechanical work.

  5. 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.

  6. Hydrogen embrittlement of titanium and its alloys - a literature review

    International Nuclear Information System (INIS)

    Hydrogen embrittlement data of titanium and its alloys is reviewed. Especially the results obtained in spent nuclear fuel repository conditions with commercially pure titanium and TiCode-12 alloy are examined. The results show that the mechanical properties of titanium are not much affected by hydrogen when tested by smooth specimens. Much greater effects can be expected with notched fracture mechanics specimens. However, only limeted data is available. Hydrogen distribution in titanium is affected by stress, alloy composition and temperature gradients. In order to model the hydrogen-induced crack growth in titanium much more mechanistic work is needed especially to understand the behaviour of hydrogen in crack tip stress field. (author)

  7. Effective interactions approach to phase stability in alloys under irradiation

    International Nuclear Information System (INIS)

    Phase stability in alloys under irradiation is studied considering effective thermodynamic potentials. A simple kinetic model of a binary alloy with phase separation is investigated. Time evolution in the alloy results from two competing dynamics: thermal diffusion, and irradiation induced ballistic exchanges The dynamical (steady state) phase diagram is evaluated exactly performing Kinetic Monte Carlo simulations. The solution is then compared to two theoretical frameworks: the effective quasi-interactions model as proposed by Vaks and Kamishenko, and the effective free energy model as proposed by Martin. New developments of these models are proposed to allow for quantitative comparisons. Both theoretical frameworks yield fairly good approximations to the dynamical phase diagram

  8. Correlation effects driven by reduced dimensionality in magnetic surface alloys

    Indian Academy of Sciences (India)

    U Manju

    2015-06-01

    The evolution of electronic properties and correlation effects in manganese-based two-dimensional magnetic surface alloys are discussed. Enhanced correlations resulting from the reduced dimensionality of the surface alloys lead to the modification of the core level and valence band electronic structures resulting in the appearance of distinct satellite features. Apart from this, surface alloying-induced strong modifications in the substrate surface states arising from charge reorganization and electron transfer to the surface states as well as band-gap openings are also discussed.

  9. Fe-Ni恒弹合金激光冲击力学性能异化现象研究%Study on mechanical properties in the laser spot center of Fe-Ni elastic alloy induced by laser shock processing

    Institute of Scientific and Technical Information of China (English)

    裴旭; 吴建华; 蒋素琴; 许兆美

    2012-01-01

    In order to study the rebound phenomenon of mechanical properties in the spot center of metallic material induced by laser shock processing, Ni42CrTiAl, a Fe-Ni elastic alloy material, was processed by high-energy neodymium glass pulse laser. Then the distribution of the residual stress on the elastic alloy surface was tested with an X-ray strain gauge. The results showed that there was a high distribution of residual cotnpressive stress in the shocked region and there was a rebound phenomenon of mechanical properties in the spot center region where the residual stress values slightly less than its surrounding area. And then for the purpose of further studying the distribution of the residual stress induced by laser shock processing, the finite elementsimulation software was introduced to simulate the shocking experiment. The simulation results showed that there was also a high distribution of residual compressive stress in the shocked region and a rebound phenomenon of mechanical properties in the spot center region. The simulation results are in good agreement with the measurement Finally the formation mechanism of rebound phenomenon of the material mechanical properties in the center region was explored from the angle of the movement, the reflection and the reverse effect of the shock wave. This study result is benefit to optimize the process of the laser shock processing and laser parameter selection.%为了研究激光冲击金属材料后,光斑中心区域材料力学性能异化现象,采用钕玻璃脉冲激光器产生的高能脉冲激光冲击强化型Fe-Ni恒弹合金(Ni42CrTiAl)材料.冲击后采用X射线应力仪对恒弹合金试样冲击区域表面进行了X射线衍射分析,测试了冲击区域残余应力分布情况.结果表明,在试样冲击区域产生了很高的残余压应力,且在光斑中心区域,残余应力值要略小于中心周围区域,出现了力学性能反弹现象.采用有限元模拟软件对冲击试验进行有限

  10. Local phase transformation in alloys during charged-particle irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lam, N.Q.; Okamoto, P.R.

    1984-10-01

    Among the various mechanisms and processes by which energetic irradiation can alter the phase stability of alloys, radiation-induced segregation is one of the most important phenomena. Radiation-induced segregation in alloys occurs as a consequence of preferential coupling between persistent fluxes of excess defects and solute atoms, leading to local enrichment or depletion of alloying elements. Thus, this phenomenon tends to drive alloy systems away from thermodynamic equilibrium, on a local scale. During charged-particle irradiations, the spatial nonuniformity in the defect production gives rise to a combination of persistent defect fluxes, near the irradiated surface and in the peak-damage region. This defect-flux combination can modify the alloy composition in a complex fashion, i.e., it can destabilize pre-existing phases, causing spatially- and temporally-dependent precipitation of new metastable phases. The effects of radiation-induced segregation on local phase transformations in Ni-based alloys during proton bombardment and high-voltage electron-microscope irradiation at elevated temperatures are discussed.

  11. Oxidation behavior of nickel-base superalloys and High Strength Low Alloy (HSLA) steels at elevated temperatures

    Science.gov (United States)

    Talekar, Anjali S.

    Alloy C-22 (UNS N06022) and High Strength Low Alloy (HSLA) steels are candidate materials for use in outer layer of waste storage packages and as rock bolts in the underground roof supports at Yucca Mountain nuclear waste repository respectively. Oxidation kinetics of three Ni-base Superalloys and two HSLA Steels, Split Set Friction Rock Stabilizers (SS-46) and Swellex Mn-24, have been determined by isothermal high temperature continuous measurement thermogravimetry at temperatures ranging between 600°C to 1100°C in pure oxygen atmosphere for predetermined periods of exposures (48 hours for the Superalloys and 100 hours for HSLA steels). The two other Ni-base Superalloys selected were Alloy-263 (UNS N07263) and Alloy-282. These are similar in their Cr composition to Alloy C-22 and have variations in the contents of other alloying elements namely Co and Mo. The alloys were selected for comparison of their oxidation resistance with C-22 as a baseline material. All three Superalloys are known chromia formers. All the superalloys were evaluated for determining their kinetic parameters and the activation energies for the superalloys were also calculated. The activation energy for the parabolic regime of Alloy-282 is found to be 232 kJ/mol. The slope of the curves on a plot of kp as a function of (1/T) show Alloy-282 to have better oxidation resistance up to 980°C and thereafter the rate constants are similar for all three alloys, but when activation energies over the whole temperature range are calculated, Alloy-263 shows the best average oxidation resistance. Surface characterization by means of microscopy as well as X-ray photoelectron spectroscopy showed the nature of oxides formed. Based on the kinetics and the characterization, proposed mechanisms for oxidation of these alloys at high temperatures are put forth. Temperature modulated thermogravimetry was used for studies on HSLA steels. The imposed sinusoidal temperature modulations on the isothermal temperature

  12. Influence of alloying and secondary annealing on anneal hardening effect at sintered copper alloys

    Indian Academy of Sciences (India)

    Svetlana Nestorovic

    2005-08-01

    This paper reports results of investigation carried out on sintered copper alloys (Cu, 8 at%; Zn, Ni, Al and Cu–Au with 4 at%Au). The alloys were subjected to cold rolling (30, 50 and 70%) and annealed isochronally up to recrystallization temperature. Changes in hardness and electrical conductivity were followed in order to investigate the anneal hardening effect. This effect was observed after secondary annealing also. Au and Al have been found to be more effective in inducing anneal hardening effect.

  13. Electric field fluctuations in liquid tellurium alloys a hint to bond character

    OpenAIRE

    Paulick, C.A.; Brinkmann, R.; Elwenspoek, M; Hartrott, von, M.; KIEHL, M.; Maxim, P.; Quitmann, D.

    1985-01-01

    Atomic scale electric field fluctuations in liquid tellurium alloys are detected as they induce nuclear spin relaxation rate RQ in noble gas impurity atoms, via quadrupolar interaction. Results for Xe in liquid Ag, Ga, In, Tl, Ge, Sn---Te alloys are discussed, assuming that bonding in these alloys may be described as a mixture of metallic, covalent and ionic bonding. Using an inhomogeneous model, and obtaining the metallic fraction from electrical conductivity, the Xe R0 data are used to deri...

  14. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.

    2007-04-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T e and N e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T e and N e for aluminum in aluminum alloys as a marker for the correct alloying using an optical fiber probe.

  15. Characterization for Fusion Candidate Vanadium Alloys

    Institute of Scientific and Technical Information of China (English)

    T. Muroga; T. Nagasaka; J. M. Chen; Z. Y. Xu; Q. Y. Huang; y. C. Wu

    2004-01-01

    This paper summarizes recent achievements in the characterization of candidate vanadium alloys obtained for fusion in the framework of the Japan-China Core University Program.National Institute for Fusion Science (NIFS) has a program of fabricating high-purity V-4Cr4Ti alloys. The resulting products (NIFS-HEAT-1,2), were characterized by various research groups in the world including Chinese partners. South Western Institute of Physics (SWIP) fabricated a new V-4Cr-4Ti alloy (SWIP-Heat), and carried out a comparative evaluation of hydrogen embrittlement of NIFS-HEATs and SWIP-Heat. The tensile test of hydrogen-doped alloys showed that the NIFS-HEAT maintained the ductility to relatively high hydrogen levels.The comparison of the data with those of previous studies suggested that the reduced oxygen level in the NIFS-HEATs should be responsible for the increased resistance to hydrogen embrittlement.Based on the chemical analysis data of NIFS-HEATs and SWIP-Heats, neutron-induced activation was analyzed in Institute of Plasma Physics (IPP-CAS) as a function of cooling time after the use in the fusion first wall. The results showed that the low level of Co dominates the activity up to 50 years followed by a domination of Nb or Nb and Al in the respective alloys. It was suggested that reduction of Co and Nb, both of which are thought to have been introduced via cross-contamination into the alloys from the molds used should be crucial for reducing further the activation.

  16. On the mechanical properties of TiNb based alloys

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-15

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

  17. 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.

  18. Refractory alloy component fabrication

    International Nuclear Information System (INIS)

    Purpose of this report is to describe joining procedures, primarily welding techniques, which were developed to construct reliable refractory alloy components and systems for advanced space power systems. Two systems, the Nb-1Zr Brayton Cycle Heat Receiver and the T-111 Alloy Potassium Boiler Development Program, are used to illustrate typical systems and components. Particular emphasis is given to specific problems which were eliminated during the development efforts. Finally, some thoughts on application of more recent joining technology are presented. 78 figures

  19. Pareto-optimal alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Johannesson, Gisli Holmar; Ruban, Andrei; Skriver, Hans Lomholt; Jacobsen, Karsten Wedel; Nørskov, Jens Kehlet

    2003-01-01

    cost. In this letter we present a database consisting of the lattice parameters, bulk moduli, and heats of formation for over 64 000 ordered metallic alloys, which has been established by direct first-principles density-functional-theory calculations. Furthermore, we use a concept from economic theory......, the Pareto-optimal set, to determine optimal alloy solutions for the compromise between low compressibility, high stability, and cost....

  20. Survey of degradation modes of four nickel-chromium-molybdenum alloys

    International Nuclear Information System (INIS)

    This report examines the degradation modes of four Ni-Cr-Mo alloys under conditions relevant to the Yucca Mountain Site Characterization Project (YMP). The materials considered are Alloys C-276, C-4, C-22, and 625 because they have desirable characteristics for the conceptual design (CD) of the high-level radioactive-waste containers presented in the YMP Site Characterization Plan (SCP). The types of degradation covered in this report are general corrosion; localized corrosion, including pitting and crevice corrosion; stress corrosion cracking in chloride environments; hydrogen embrittlement (HE); and undesirable phase transformations due to a lack of phase stability. Topics not specifically addressed are welding concerns and microbiological corrosion. The four Ni-Cr-Mo alloys have excellent corrosion resistance in chloride environments such as seawater as well as in more aggressive environments. They have significantly better corrosion resistance than the six materials considered for the CD waste container in the YMP SCP. (Those six materials are Types 304L and 3161L stainless steels, Alloy 825, unalloyed copper, Cu(70)-Ni(30), and 7% aluminum bronze.) In seawater, the Ni-Cr-Mo alloys have negligible general corrosion rates and show little evidence of localized corrosion. The four base materials of these alloys are expected to have nearly indistinguishable corrosion resistance in the YMP environments. The strength requirements of the SCP-CD waste container are met by these materials in the annealed condition; in this condition, they are highly resistant to HE. Historically, HE has been noted when these materials have been strengthened (cold-worked) and used in sour gas (H2S and CO2) well service -- conditions that are not expected for the YMP. Metallurgical phase stability may be a concern under conditions favoring (1) the formation of intermetallics and carbides, and (2) microstructural ordering

  1. Survey of degradation modes of four nickel-chromium-molybdenum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gdowski, G.E. [KMI Energy Services, Livermore, CA (United States)

    1991-03-01

    This report examines the degradation modes of four Ni-Cr-Mo alloys under conditions relevant to the Yucca Mountain Site Characterization Project (YMP). The materials considered are Alloys C-276, C-4, C-22, and 625 because they have desirable characteristics for the conceptual design (CD) of the high-level radioactive-waste containers presented in the YMP Site Characterization Plan (SCP). The types of degradation covered in this report are general corrosion; localized corrosion, including pitting and crevice corrosion; stress corrosion cracking in chloride environments; hydrogen embrittlement (HE); and undesirable phase transformations due to a lack of phase stability. Topics not specifically addressed are welding concerns and microbiological corrosion. The four Ni-Cr-Mo alloys have excellent corrosion resistance in chloride environments such as seawater as well as in more aggressive environments. They have significantly better corrosion resistance than the six materials considered for the CD waste container in the YMP SCP. (Those six materials are Types 304L and 3161L stainless steels, Alloy 825, unalloyed copper, Cu(70)-Ni(30), and 7% aluminum bronze.) In seawater, the Ni-Cr-Mo alloys have negligible general corrosion rates and show little evidence of localized corrosion. The four base materials of these alloys are expected to have nearly indistinguishable corrosion resistance in the YMP environments. The strength requirements of the SCP-CD waste container are met by these materials in the annealed condition; in this condition, they are highly resistant to HE. Historically, HE has been noted when these materials have been strengthened (cold-worked) and used in sour gas (H{sub 2}S and CO{sub 2}) well service -- conditions that are not expected for the YMP. Metallurgical phase stability may be a concern under conditions favoring (1) the formation of intermetallics and carbides, and (2) microstructural ordering.

  2. Effects of alloying elements on nitrogen diffusion behavior around TiN/Ti interface α region in as-cast titanium alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To characterize the effects of alloying elements on inclusion dissolution of titanium nitride, the content profiles of elements around TiN/Ti boundary α phase regions in liquid titanium alloys have been experimentally carried out. Four kinds of commercial alloys of CpTi, Ti64, Ti17 and Ti6242 containing different α-stabilizing or β-stabilizing elements are examined through artificially embedding the TiN sponge particle into liquid alloys in VAR conditions. The content profiles of nitrogen and alloying elements around TiN/Ti boundary were measured by WDX and microprobe for as-cast samples. The content profiles of nitrogen and alloying elements around N-containing solid in αTi region of these alloys show a common features of a steep change. In particular, the content profiles of elements for Ti6242 demonstrate unique change of a more gentle change tendency and further deeper into the alloy matrix. The experiment results show that, the differences among composite effects of alloying elements in different alloys within nitrogen-induced diffusion α region result in different dissolution and diffusion behaviors to overcome the α phase region barriers.

  3. Texture in low-alloyed uranium alloys

    International Nuclear Information System (INIS)

    The dependence of the preferred orientation of cast and heat-treated polycrystalline adjusted uranium and uranium -0.1 w/o chromium alloys on the production process was studied. The importance of obtaining material free of preferred orientation is explained, and a survey of the regular methods to determine preferred orientation is given. Dilatometry, tensile testing and x-ray diffraction were used to determine the extent of the directionality of these alloys. Data processing showed that these methods are insufficient in a case of a material without any plastic forming, because of unreproducibility of results. Two parameters are defined from the results of Schlz's method diffraction test. These parameters are shown theoretically and experimentally (by extreme-case samples) to give the deviation from isotropy. Application of these parameters to the examined samples showes that cast material has preferred orientation, though it is not systematic. This preferred orientation was reduced by adequate heat treatments

  4. WC-3015 alloy (high-temperature alloy)

    International Nuclear Information System (INIS)

    WC-3015 Nb alloy containing 28 to 30 Hf, 1 to 2 Zr, 13 to 16 W, 0 to 4 Ta, 0 to 5 Ti, 0.07 to 0.33 C, less than or equal to 0.02 N, less than or equal to 0.03 O, less than or equal to 0.001 H was developed for use at high temperature in oxidizing environments. Its composition can be tailored to meet specific requirements. When WC-3015 is exposed to O at elevated temperature, Hf and Nb oxidized preferentially and HfO2 dissolves in Nb2O5 to form 6HfO-Nb2O5. This complex oxide has a tight cubic lattice which resists the diffusion of O into the substrate. During 24-h exposure to air at 24000F, the alloy oxidizes to a depth of approximately 0.035 in. with a surface recession of 0 to 0.004 in. Oxidation resistance of WC-3015 welds and base material can be further enhanced greatly by applying silicide coatings. WC-3015 alloy can be machined by conventional and electrical-discharge methods. It can be hot worked readily by extrusion, forging or rolling. Cold working can be used at room or elevated temperature. It can be welded by the electron-beam or Tig processes. Physical constants, typical mechanical properties at 75 to 24000F, and effects of composition and heat treatment on tensile and stress-rupture properties of the alloy are tabulated

  5. High-strength shape memory steels alloyed with nitrogen

    International Nuclear Information System (INIS)

    Since shape memory effect in Fe-Mn-Si systems was observed, increasing attention has been paid to iron based shape memory alloys due to their great technological potential. Properties of Fe-Mn-Si shape memory alloys have been improved by alloying with Cr, Ni, Co and C. A significant improvement on shape memory, mechanical and corrosion properties is attained by introducing nitrogen in Fe-Mn-Si based systems. By increasing the nitrogen content, strength of the matrix increases and the stacking fault energy decreases, which promote the formation of stress induced martensite and decrease permanent slip. The present authors have shown that nitrogen alloyed shape memory steels exhibit recoverable strains of 2.5--4.2% and recovery stresses of 330 MPa. In some cases, stresses over 700 MPa were attained at room temperature after cooling a constrained sample. Yield strengths of these steels can be as high as 1,100 MPa and tensile strengths over 1,500 MPa with elongations of 30%. In the present study, effect of nitrogen alloying on shape memory and mechanical properties of Fe-Mn-Si, Fe-Mn-Si-Cr-Ni and Fe-Mn-Cr-Ni-V alloys is studied. Nitrogen alloying is shown to exhibit a beneficial effect on shape memory properties and strength of these steels

  6. Atomic displacements in bcc dilute alloys

    Indian Academy of Sciences (India)

    Hitesh Sharma; S Prakash

    2007-04-01

    We present here a systematic investigation of the atomic displacements in bcc transition metal (TM) dilute alloys. We have calculated the atomic displacements in bcc (V, Cr, Fe, Nb, Mo, Ta and W) transition metals (TMs) due to 3d, 4d and 5d TMs at the substitutional site using the Kanzaki lattice static method. Wills and Harrison interatomic potential is used to calculate the atomic force constants, the dynamical matrix and the impurity-induced forces. We have thoroughly investigated the atomic displacements using impurities from 3d, 4d and 5d series in the same host metal and the same impurity in different hosts. We have observed a systematic pattern in the atomic displacements for Cr-, Fe-, Nb-, Mo-, Ta- and W-based dilute alloys. The atomic displacements are found to increase with increase in the number of d electrons for all alloys considered except for V dilute alloys. The 3d impurities are found to be more easily dissolved in the 3d host metals than 4d or 5d TMs whereas 4d and 5d impurities show more solubility in 4d and 5d TMs. In general, the relaxation energy calculation suggests that impurities may be easily solvable in 5d TM hosts when compared to 3d or 4d TMs.

  7. High-strength iron aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.; Marrero-Santos, Y.; Maziasz, P.J.

    1995-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile density due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications, despite their excellent corrosion properties. Improvements in room temperature tensile ductility have been realized mainly through alloying effects, changes in thermomechanical processing to control microstructure, and by control of the specimen`s surface condition. Ductilities of 10-20% and tensile yield strengths as high as 500 MPa have been reported. In terms of creep-rupture strength, small additions of Mo, Nb, and Zr have produced significant improvements, but at the expense of weldability and room-temperature tensile ductility. Recently an alloy containing these additions, designated FA-180, was shown to exhibit a creep-rupture life of over 2000 h after a heat treatment of 1 h at 1150{degrees}C. This study presents the results of creep-rupture tests at various test temperatures and stresses and discusses the results as part of our effort to understand the strengthening mechanisms involved with heat treatment at 1150{degrees}C.

  8. Chemical bond approach to metals and alloys

    International Nuclear Information System (INIS)

    The BCS theory of superconductivity was extended to the transition elements and their alloys by a chemical bond approach based on the electronic configurations of the Engel-- Brewer theory of alloys. The net attractive potential between electrons in Cooper pairs, V/sub BCS/, for the late transition series elements and alloys is shown to arise mainly from a generalized electron--electron interaction related to bonding of electrons on the d level alone, the phonon-induced attraction being nearly zero. A mechanism is proposed in which a scattering of superconducting d electrons into nonsuperconducting s and p states is responsible for a predictable reduction in V/sub BCS/. The electron-per-atom ratio and a new chemical parameter, the average atomic radius for coordination twelve, were applied successfully to the prediction of the maximum energy product of multiphase commercial permanent magnets. The correlations developed for the maximum energy product with these two parameters can be applied to optimize the compositions of existing permanent magnets or suggest hypothetical alloy mixtures of possibly better magnetic properties. Heats of reaction of the

  9. Ageing of zirconium alloy components

    International Nuclear Information System (INIS)

    India has two types (pressurized heavy water reactors (PHWRs) and boiling water reactors (BWRs)) of commercial nuclear reactors in operation, in addition to research reactors. Many of the life limiting critical components in these reactors are fabricated from zirconium alloys. The progressive degradation of these components caused by the cumulative exposure of high energy neutron irradiation with increasing period of reactor operation was monitored to assess the degree of ageing. The components/specimens examined included fuel element claddings removed from BWRs, pressure tubes and garter springs removed from PHWRs and calandria tube specimens used in PHWRs. The tests included tension test (for cladding, garter spring), fracture toughness test (for pressure tube), crush test (for garter spring), and measurement of irradiation induced growth (for calandria tube). Results of various tests conducted are presented and applications of the test results are elaborated for residual life estimation/life extension of the components

  10. Titanium alloys. Advances in alloys, processes, products and applications

    OpenAIRE

    Blenkinsop, P.

    1993-01-01

    The last few years have been a period of consolidation of existing alloys and processes. While the aerospace industry remains the principal driving force for alloy development, the paper illustrates examples of new markets being established in "older" alloys, by a combination of product/process development and a re-examination of engineering design parameters. Considerable attention is still being directed towards the titanium aluminide systems, but other more conventional alloy developments ...

  11. Correlation between diffusion barriers and alloying energy in binary alloys

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg; Rossmeisl, Jan; Stephens, Ifan; Schiøtz, Jakob

    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....

  12. GRAIN-BOUNDARY PRECIPITATION UNDER IRRADIATION IN DILUTE BINARY ALLOYS

    Institute of Scientific and Technical Information of China (English)

    S.H. Song; Z.X. Yuan; J. Liu; R.G.Faulkner

    2003-01-01

    Irradiation-induced grain boundary segregation of solute atoms frequently bring about grain boundary precipitation of a second phase because of its making the solubility limit of the solute surpassed at grain boundaries. Until now the kinetic models for irradiation-induced grain boundary precipitation have been sparse. For this reason, we have theoretically treated grain boundary precipitation under irradiation in dilute binary alloys. Predictions ofγ'-Ni3Si precipitation at grain boundaries ave made for a dilute Ni-Si alloy subjected to irradiation. It is demonstrated that grain boundary silicon segregation under irradiation may lead to grain boundaryγ'-Ni3 Si precipitation over a certain temperature range.

  13. Kinetic process of mechanical alloying in Fe50Cu50

    DEFF Research Database (Denmark)

    Huang, J.Y.; Jiang, Jianzhong; Yasuda, H.;

    1998-01-01

    It is shown that mechanical alloying in the immiscible Fe-Cu system is governed by the atomic shear event and shear-induced diffusion process. We found that an alpha-to-gamma phase transformation, as evidenced by the Nishiyama-Wasserman orientation relationship, occurs by simultaneous shearing pr...... structures, until a complete fee Fe-Cu solid solution is formed. The results provide significant insight into the understanding of recent experiments showing that chemical mixing of immiscible elements can bd induced by mechanical alloying. [S0163-1829(98)51342-2]....

  14. Influence of system and degree of alloying on the parameters of shape-memory effect in titanium alloys

    International Nuclear Information System (INIS)

    The influence of chemical composition, compression degree, heating rate on characteristics of shape memory effect of Ti-Nb, Ti-V, Ti-Al-V, Ti-Al-V-Cr is studied. A comparative analysis is made between experimentally defined values of restitution deformation degree and calculated values of crystographically reversible deformation of martensitic transformation. Main reasons for non complete restitution of form in the titanium base alloy are as the formation of embrittling ω-phase in titanium alloys of critical composition with a β-stabilizer; the proximity of martensitic transformation-induced stresses and sliding ones on deformation; low thermal stability of β- and α''-phase of titanium alloys in the range of temperatures of reverse martensitic transformation. Aluminium and chromium alloying of titanium alloys permits increasing the value of restitution deformation due to the suppression of ω-phase formation during quenching of critical composition alloys and the increase of sliding stresses. The optimal composition of the titanium alloy is proposed

  15. Effects of service-induced ageing processes on the fatigue lifetime and toughness of low-alloy steel WB 36; Auswirkungen betrieblicher Alterungsprozesse auf Ermuedungslebensdauer und Werkstoffzaehigkeit des niedrig legierten Stahles WB 36

    Energy Technology Data Exchange (ETDEWEB)

    Szielasko, K.; Altpeter, I.; Dobmann, G. [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren (IZFP), Saarbruecken (Germany); Willer, D.; Ruoff, H. [Stuttgart Univ. (DE). Materialpruefungsanstalt (MPA)

    2008-07-01

    The heat-resistant copper alloyed ferritic steel WB 36 (15NiCuMoNb5, Material number 1.6368) is applied in German nuclear and conventional power plants for temperatures around 300 deg C as piping and pressure vessel material. The advantageous properties are due to the copper precipitates that develop during the production and manufacture processes. A thermally induced additional precipitation of copper during operation entails increased hardness, embrittlement and thus reduced toughness. Additional mechanical fatigue with high strain amplitudes and simultaneous relatively low load cycles (low cycle fatigue LCF), esp. in the temperature range 200 - 300 deg C, cause an accelerated deterioration of the material characteristics. This load situation is very common at specific piping locations in nuclear power plants. In the frame of reactor safety research IZFP in cooperation with MPA investigated the superposed effects if temperature and cyclic deformation in the material WB 36. Experimental results on the changes of micromagnetic characteristics due to different thermal and mechanical load parameters are correlated with reference data and mechano-technological characteristics determined by MPA. There are indications of possibilities to separate fatigue and embrittlement effects. [German] Der warmfeste kupferlegierte ferritische Stahl WB 36 (15NiCuMoNb5, Werkstoffnummer 1.6368) wird in deutschen Kern- und konventionellen Kraftwerken bei Temperaturen um 300 C in hohem Umfang als Rohrleitungs- und Behaelterwerkstoff eingesetzt. Seine vorteilhaften Werkstoffeigenschaften sind Kupferausscheidungen zuzuschreiben, die im Herstellungs- und Verarbeitungsprozess entstehen. Eine thermisch bedingte Nachausscheidung von Kupfer waehrend des Betriebs fuehrt hingegen zu hoeherer Haerte, Versproedung und damit zu verringerter Zaehigkeit. Bei zusaetzlicher mechanischer Ermuedung mit grossen Dehnungsamplituden bei gleichzeitig relativ wenigen Lastzyklen (Low Cycle Fatigue, LCF

  16. INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

    Directory of Open Access Journals (Sweden)

    Berat Barıs BULDUM

    2013-01-01

    Full Text Available Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attractive to designers due to their low density, only two thirds that of aluminium and its alloys [1]. The element and its alloys take a big part of modern industry needs. Especially nowadays magnesium alloys are used in automotive and mechanical (trains and wagons manufacture, because of its lightness and other features. Magnesium and magnesium alloys are the easiest of all metals to machine, allowing machining operations at extremely high speed. All standard machining operations such as turning, drilling, milling, are commonly performed on magnesium parts.

  17. 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...

  18. Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

    Energy Technology Data Exchange (ETDEWEB)

    Cabral P, A.; Garcia S, I. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Contreras V, J. A.; Garcia S, F. [Universidad Autonoma del Estado de Mexico, Facultad de Ciencias, El Cerrillo Piedras Blancas, Toluca, Estado de Mexico (Mexico); Nava, N., E-mail: agustin.cabral@inin.gob.m [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, 07730 Mexico D. F. (Mexico)

    2010-07-01

    The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634 K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by Positron annihilation lifetime spectroscopy and Moessbauer spectroscopy, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem. (Author)

  19. Effect of vapor phase corrosion inhibitor on microbial corrosion of aluminum alloys.

    Science.gov (United States)

    Yang, S S; Ku, C H; Bor, H J; Lin, Y T

    1996-02-01

    Vapor phase corrosion inhibitors were used to investigate the antimicrobial activities and anticorrosion of aluminum alloy. Aspergillus flavus, A. niger, A. versicolor, Chaetomium globosum and Penicillium funiculosum had moderate to abundant growth on the aluminum alloy AA 1100 at Aw 0.901, while there was less growth at Aw 0.842. High humidity stimulated microbial growth and induced microbial corrosion. Dicyclohexylammonium carbonate had a high inhibitory effect on the growth of test fungi and the microbial corrosion of aluminum alloy, dicyclohexylammonium caprate and dicyclohexylammonium stearate were the next. Aluminum alloy coating with vapor phase corrosion inhibitor could prevent microbial growth and retard microbial corrosion. PMID:10592784

  20. INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

    OpenAIRE

    Berat Barıs BULDUM; Aydın SIK; Iskender OZKUL

    2013-01-01

    Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attra...

  1. Productive Machining of Titanium Alloys

    OpenAIRE

    Čejka, Libor

    2013-01-01

    This diploma thesis is focused on a productive machining of titanium alloys. At the beginning it deals about titanium and its alloys. It describes chip generation mechanism, tool blunting and surface quality. Further it contains modern strategies of efficient titanium alloys machining. Then it analyzes contemporary manufacturing technology of hinge made of titanium alloy Ti-6Al-4V in Frentech Aerospace s.r.o. company, and at the end finds possibility of savings by inovation of roughing process.

  2. 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.

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

    International Nuclear Information System (INIS)

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

  4. Effect of Alloying Elements in Hot-Rolled Metastable β-Titanium Alloys. Part II: Mechanical Properties

    Science.gov (United States)

    Manda, Premkumar; Chakkingal, Uday; Singh, A. K.

    2016-07-01

    This paper describes the tensile properties, flow and work-hardening behavior of four metastable β-titanium alloys Ti-5Al-5Mo-5V-3Cr (A1), Ti-5Al-3.5Mo-7.2V-3Cr (A2), Ti-5Al-5Mo-8.6V-1.5Cr (A3), and Ti-5Al-3.5Mo-5V-3.94Cr (A4) in α+β hot-rolled condition. The decreasing order of average strength parameters ( σ YS and σ UTS) is A4, A2, A1, and A3. The maximum strength observed in alloy A4 is due to the presence of highest wt. fraction of Cr. The elongation is the maximum and minimum in alloys A3 and A4, respectively. These alloys display moderate to high percent in-plane anisotropy ( A IP) and reasonably low anisotropic index ( δ) values. Both the A IP and δ values are maximum and minimum in alloys A1 and A3, respectively. The yield locus plots also exhibit the presence of anisotropy due to relatively large differences in yield strength values along tension and compression directions. The flow behavior of alloys A1, A2, and A4 follows Swift equation, while the alloy A3 displays best fit with Holloman equation. The presence of prestrain ( ɛ 0) in hot-rolled materials before tensile testing has an important bearing on the flow curves of A1, A2, and A4 alloys. The instantaneous work-hardening rate curves of the alloys A1, A2, and A3 exhibit all the three typical stages (stage I, stage II, and stage III) in RD samples, while the alloy A4 shows the presence of only stage I and stage III. The 45 deg to RD and TD samples of alloys A1, A2, and A4 display only stage I. The stages I and III as well as I and II are present in alloy A3 in 45 deg to RD and TD samples, respectively. Dislocation-controlled strain hardening occurs in all the three stages of these alloys in the absence of stress-induced martensitic transformation (α″) and twinning. Slip is the predominant deformation mechanism during tensile testing. Three types of slip lines, i.e., planar, wavy, and intersecting have been observed close to fracture surfaces of post tensile-tested specimens.

  5. Effect of Alloying Elements in Hot-Rolled Metastable β-Titanium Alloys. Part II: Mechanical Properties

    Science.gov (United States)

    Manda, Premkumar; Chakkingal, Uday; Singh, A. K.

    2016-04-01

    This paper describes the tensile properties, flow and work-hardening behavior of four metastable β-titanium alloys Ti-5Al-5Mo-5V-3Cr (A1), Ti-5Al-3.5Mo-7.2V-3Cr (A2), Ti-5Al-5Mo-8.6V-1.5Cr (A3), and Ti-5Al-3.5Mo-5V-3.94Cr (A4) in α+β hot-rolled condition. The decreasing order of average strength parameters (σ YS and σ UTS) is A4, A2, A1, and A3. The maximum strength observed in alloy A4 is due to the presence of highest wt. fraction of Cr. The elongation is the maximum and minimum in alloys A3 and A4, respectively. These alloys display moderate to high percent in-plane anisotropy (A IP) and reasonably low anisotropic index (δ) values. Both the A IP and δ values are maximum and minimum in alloys A1 and A3, respectively. The yield locus plots also exhibit the presence of anisotropy due to relatively large differences in yield strength values along tension and compression directions. The flow behavior of alloys A1, A2, and A4 follows Swift equation, while the alloy A3 displays best fit with Holloman equation. The presence of prestrain (ɛ 0) in hot-rolled materials before tensile testing has an important bearing on the flow curves of A1, A2, and A4 alloys. The instantaneous work-hardening rate curves of the alloys A1, A2, and A3 exhibit all the three typical stages (stage I, stage II, and stage III) in RD samples, while the alloy A4 shows the presence of only stage I and stage III. The 45 deg to RD and TD samples of alloys A1, A2, and A4 display only stage I. The stages I and III as well as I and II are present in alloy A3 in 45 deg to RD and TD samples, respectively. Dislocation-controlled strain hardening occurs in all the three stages of these alloys in the absence of stress-induced martensitic transformation (α″) and twinning. Slip is the predominant deformation mechanism during tensile testing. Three types of slip lines, i.e., planar, wavy, and intersecting have been observed close to fracture surfaces of post tensile-tested specimens.

  6. Hydrogen in titanium alloys

    International Nuclear Information System (INIS)

    The titanium alloys that offer properties worthy of consideration for fusion reactors are Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242S) and Ti-5Al-6Sn-2Zr-1Mo-Si (Ti-5621S). The Ti-6242S and Ti-5621S are being considered because of their high creep resistance at elevated temperatures of 5000C. Also, irradiation tests on these alloys have shown irradiation creep properties comparable to 20% cold worked 316 stainless steel. These alloys would be susceptible to slow strain rate embrittlement if sufficient hydrogen concentrations are obtained. Concentrations greater than 250 to 500 wppm hydrogen and temperatures lower than 100 to 1500C are approximate threshold conditions for detrimental effects on tensile properties. Indications are that at the elevated temperature - low hydrogen pressure conditions of the reactors, there would be negligible hydrogen embrittlement

  7. Welding of refractory alloys

    International Nuclear Information System (INIS)

    This review primarily summarizes welding evaluations supported by NASA-Lewis Research Center in the 1960s. A literature search run in preparation for this review indicates that more recent work is modest by comparison. Hence, this review restates these accomplishments briefly and addresses opportunities which have evolved in welding technology (such as lasers) in the intervening decade. Emphasis in this review is given to tantalum- and niobium-base alloys. Considerable work was also done to assure that a consistent comparison was made with tungsten. A wide variety of candidate alloys derived primarily from developments directed at aircraft propulsion applications were available. Early efforts by NASA were directed at screening studies to select promising structural alloys for the space power application. This objective required fine tuning of welding procedures, e.g., the demonstration of stringent standards for control of welding atmosphere to assure good corrosion resistance in liquid alkali metals. 16 figures, 6 tables

  8. Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    Deexith Reddy

    2016-07-01

    Full Text Available Shape memory alloys (SMAs are metals that "remember" their original shapes. SMAs are useful for such things as actuators which are materials that "change shape, stiffness, position, natural frequency, and other mechanical characteristics in response to temperature or electromagnetic fields" The potential uses for SMAs especially as actuators have broadened the spectrum of many scientific fields. The study of the history and development of SMAs can provide an insight into a material involved in cutting-edge technology. The diverse applications for these metals have made them increasingly important and visible to the world. This paper presents the working of shape memory alloys , the phenomenon of super-elasticity and applications of these alloys.

  9. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.

    2007-04-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T(e and N(e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T(e and N(e for the aluminum in aluminum alloys using an optical fiber probe.

  10. Plasticity of oxide dispersion strengthened ferritic alloys

    International Nuclear Information System (INIS)

    The object of this work is to study the plasticity mechanisms of two oxide dispersion strengthened ferritic alloys, DT and DY. Microstructural characterisation has been performed on DT and DY alloys by optical, scanning and transmission electron microscopy. These materials, strengthened by an oxide dispersion, contain an intermetallic χ phase precipitated on grain boundaries. The χ phase, stable up to 900 deg, can be dissolved into the matrix by heat treatment beyond 1 000 deg. Between 20 and 700 deg, according to tensile tests, the DY alloy which is strengthened by a fine dispersion of yttria particles is more resistant and less ductile than DT alloy, strengthened by titanium oxides. Tensile tests performed at room temperature, in the chamber of a SEM, have shown that micro-cracking of the χ phase coincides with the first stage of the macroscopic yielding. The cavities initiated by the χ phase micro-cracking induce a ductile fracture of the matrix. A dynamic strain ageing mechanism has been observed around 400 deg, which is attributed to the Mo contribution. Between 20 and 700 deg, comparison of tensile properties of alloys with or without χ phase has shown that the intermetallic phase has a detrimental effect on the ductility, but has no influence on the mechanical strength. Creep tests have been performed between 500 and 700 deg. Thermally activated plasticity mechanisms are observed in this temperature range. The χ phase, which is always micro-cracked after tensile testing, is not damaged after creep testing below a critical stress. This behaviour is explained by the influence of strain rate through the competition between strain hardening and relaxation of the matrix. (author)

  11. Mg Sheet Metal Forming: Lessons Learned from Deep Drawing Li and Y Solid-Solution Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Agnew, Sean R [University of Virginia; Senn, Jeremy W. [University of Virginia; Horton Jr, Joe A [ORNL

    2006-01-01

    The sheet formability of current magnesium alloys at ambient temperatures is poor; however, the formability at moderately elevated temperatures can be excellent. Cylindrical cup drawing tests are used to compare the warm forming characteristics of conventional alloy AZ31B with alloys containing lithium oryttrium solid solutions. While both types of experimental alloy can have better room-temperature ductility ({epsilon}{sub f}-25-30%) than AZ31B, only the lithium alloy has comparable or better deep-drawing capacity. The results are discussed in terms of the sheet anisotropy. Particular attention is drawn to the fact that magnesium alloys exhibit poor bending ductility due to their anisotropy and mechanical twinning-induced tension-compression strength asymmetry.

  12. Increasing strength and conductivity of Cu alloy through abnormal plastic deformation of an intermetallic compound

    Science.gov (United States)

    Han, Seung Zeon; Lim, Sung Hwan; Kim, Sangshik; Lee, Jehyun; Goto, Masahiro; Kim, Hyung Giun; Han, Byungchan; Kim, Kwang Ho

    2016-08-01

    The precipitation strengthening of Cu alloys inevitably accompanies lowering of their electric conductivity and ductility. We produced bulk Cu alloys arrayed with nanofibers of stiff intermetallic compound through a precipitation mechanism using conventional casting and heat treatment processes. We then successfully elongated these arrays of nanofibers in the bulk Cu alloys to 400% of original length without breakage at room temperature using conventional rolling process. By inducing such an one-directional array of nanofibers of intermetallic compound from the uniform distribution of fine precipitates in the bulk Cu alloys, the trade-off between strength and conductivity and between strength and ductility could be significantly reduced. We observed a simultaneous increase in electrical conductivity by 1.3 times and also tensile strength by 1.3 times in this Cu alloy bulk compared to the conventional Cu alloys.

  13. Machining of Titanium Alloys

    OpenAIRE

    Karásek, Jan

    2008-01-01

    The main goal of this work is the analysis of manufacturing costs for the component of wheel´s blower. Followed by setting up the size of specific cutting force for milling operation of the titanium alloy Ti-Al6-Mo2-Cr2-Fe-Si, the used tool was a milling cutter which is made out of sintered carbide with conical and spherical face. The final values which are at intervals of 1500 to 1800 MPa were compared with the values of the Sandvik Coromant firm kc = 1690 MPa, for titanium alloy with the st...

  14. Shape memory effect alloys

    International Nuclear Information System (INIS)

    Although the pseudo- or super-elasticity phenomena and the shape memory effect were known since the 1940's, the enormous curiosity and the great interest to their practical applications emerged with the development of the NITINOL alloy (Nickel-Titanium Naval Ordance Laboratory) by the NASA during the 1960's. This fact marked the appearance of a new class of materials, popularly known as shape memory effect alloys (SMEA). The objective of this work is to present a state-of-the-art of the development and applications for the SMEA. (E.O.)

  15. Soldering of aluminium alloys

    International Nuclear Information System (INIS)

    A literature survey about soldering in general and aluminium alloys soldering in particular is presented. The existing methods of soldering aluminium alloys are described. These include soldering with flux, soldering after preliminary plating, vacuum brazipressure and temperature (NTP), sample age calculation based on 14C half life of 5570 and 5730 years, age correction for NTP, dendrochronological corrections and the relative radiocarbon concentration. All results are given with one standard deviation. Input data test (Chauvenet's criterion), gas purity test, standard deviation test and test of the data processor are also included in the program. (author)

  16. Magneto-structural transitions induced at 1.2 K in Ni.sub.2./sub.MnGa-based Heusler alloys by high magnetic field up to 60 T

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Kaštil, Jiří; Skourski, Y.; Albertini, F.; Fabbrici, S.; Arnold, Zdeněk

    2014-01-01

    Roč. 1, č. 1 (2014), s. 1-7. ISSN 2053-1591 Grant ostatní: AVČR(CZ) M100101203 Institutional support: RVO:68378271 Keywords : martensitic transition * high fi eld * Heusler alloy * Ni 2 MnGa Subject RIV: BM - Solid Matter Physics ; Magnetism

  17. Hydrogen measurement techniques for Zr alloys

    International Nuclear Information System (INIS)

    Presence of gaseous elements even in trace amounts in metals and alloys, either in free state or in combined form, has profound effect on their structural, mechanical and other properties. The presence of hydrogen in certain alloys (e.g. zircaloy) beyond certain limit leads to embrittlement resulting in loss of structural integrity of the material. Some of the techniques identified for the determination of hydrogen in solid samples include inert gas fusion (IGF), differential scanning calorimetry (DSC), nuclear techniques involving neutron scattering as well as heavy ion induced reactions on hydrogen targets, hot vacuum extraction (HVE), and mass spectrometry. This paper reviews analytical methodologies available for hydrogen determination particularly in zircaloy and presents typical results obtained in author's laboratory employing HVE-QMS. (author)

  18. Effects of V Addition on Microstructure and Hardness of Fe-C-B-Ni-V Hardfacing Alloys Cast on Steel Substrates

    Science.gov (United States)

    Rovatti, L.; Lemke, J. N.; Emami, A.; Stejskal, O.; Vedani, M.

    2015-12-01

    Fe-based hardfacing alloys containing high volume fraction of hard phases are a suitable material to be deposited as wear resistant thick coatings. In the case of alloys containing high amount of interstitial alloying elements, a key factor affecting the performance is dilution with the substrate induced by the coating process. The present research was focused on the analysis of V-bearing Fe-based alloys after calibrated carbon and vanadium additions (in the range from 3 to 5 wt.%) to a commercial Fe-C-B-Ni hardfacing alloy. Vanadium carbides with a petal-like morphology were observed in the high-V hypereutectic alloys allowing to reach hardness values above 700 HV. The solidification range shifted to higher temperatures with increasing amount of vanadium addition and in the case of hypereutectic alloys, the gap remains close to that of the original alloy. In the last step of the research, the microstructural evolution after dilution was analyzed by casting the V-rich alloys on a steel substrate. The dilution, caused by the alloying element diffusion and the local melting of the substrate, modified the microstructure and the hardness for a relevant volume fraction of the hardfacing alloys. In particular, the drop of interstitial elements induced the transition from the hypereutectic to the hypoeutectic microstructure and the formation of near-spherical V-rich carbides. Even after dilution, the hardness of the new alloys remained higher than that measured in the original Fe-C-B-Ni alloy.

  19. Pemilihan Bahan Alloy Untuk Konstruksi Gigitiruan

    OpenAIRE

    Medila Dahlan

    2008-01-01

    Pada kedokteran gigi bahan alloy sangat banyak digunakan dalam segala bidang. Dalam pembuatan konstruksi gigitiman biasanya digunakan alloy emas, alloy kobalt kromium, alloy nikei kromium dan alloy stainless steel sebagai komponen gigitiman kerangka logam serta pembuatan mahkota dan jembatan. Pemilihan bahan alloy dapat dilakukan berdasarkan sifat yang dimiiiki oleh masing-masing bahan alloy sehingga akan didapat hasil konstmksi gigitiruan yang memuaskan. Pada pemakaiannya didaiam mulut...

  20. Hydrogen embrittlement of vanadium alloys

    International Nuclear Information System (INIS)

    The mechanical properties of several vanadium alloys were measured with the hydrogen concentration high up to 113 mg/kg. The results showed that the alloys with low mechanical strength had better properties against hydrogen embrittlement. Oxygen in the alloy, especially that in the alloys with high strength, could enhance the hydrogen embrittlement. Mechanism analysis was given to show that the brittle fracture was mainly caused by intergranular failure. The effects of oxygen concentration and the strength of the alloy were both resulted from their contributions to the grain strength and the grain boundary strength

  1. Galvanic corrosion in odontological alloys

    International Nuclear Information System (INIS)

    Galvanic corrosion can occur when different alloys are placed in direct contact within the oral cavity or within tissues. Concern has been expressed associated with the coupling of selected restorative materials as well as implant material with various alloys used for restorative procedures. This could be critical if the crown or bridge had subgingival finish line with a metallic zone in contact with the tissue, and the implant was made in titanium alloy. The present work shows the results of galvanic coupling studies done on implants of titanium alloy connected to nickel-chromium and cobalt-chromium alloys. (Author)

  2. Structural and magnetic properties of nanocrystalline Fe–Co–Si alloy powders produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Shyni, P.C.; Perumal, Alagarsamy, E-mail: perumal@iitg.ernet.in

    2015-11-05

    We report the structural and magnetic properties of nanocrystalline Fe{sub 100−x−y}Co{sub y}Si{sub x} (x = 10, 15, y = 0–20) alloy powders prepared by mechanical alloying process in a planetary ball mill. All the as-milled powders exhibit non-equilibrium α-Fe(Co,Si) solid solution with average crystallite size of 7–11 nm. The lattice constant increases initially up to 10 at.% Co and then decreases with further increase in Co content due to delay in dissolution of Co into Fe lattice by the introduction of more Si. The variations of structural parameters such as average crystallite size, dislocation density and fraction of grain boundary as a function of Co content show good correlations among them. The substitution of Co in Fe{sub 100−x−y}Co{sub y}Si{sub x} alloy powder increases both saturation magnetization and coercivity due to atomic ordering which induce additional magnetic anisotropy. Thermomagnetization studies reveal that Curie temperature (T{sub C}) increases at a rate of 4 K per at.% Co for Co content up to 10 at.% and the rate of increase in T{sub C} reduces to 1.4 K per at.% Co for higher Co addition. The variation of structural and magnetic parameters reveals a strong dependence on the composition of Fe–Co–Si alloy. The observed results show the improvement in soft magnetic properties of nanocrystalline Fe–Co–Si alloy powders by proper substitution of Co and Si for Fe. - Graphical abstract: Structural and magnetic properties of nanocrystalline Fe{sub 100−x−y}Co{sub y}Si{sub x} alloy powders prepared by mechanical alloying process in a planetary ball mill are reported. The non-equilibrium solid solution with nanosized crystallites could be obtained for all the alloy powders. The substitution of Co in Fe{sub 100−x−y}Co{sub y}Si{sub x} alloy powder increases both saturation magnetization and coercivity. The Curie temperature also increases with increasing Co content. The observed results show the improvement in soft magnetic

  3. Ferromagnetic bulk glassy alloys

    International Nuclear Information System (INIS)

    This paper deals with the review on the formation, thermal stability and magnetic properties of the Fe-based bulk glassy alloys in as-cast bulk and melt-spun ribbon forms. A large supercooled liquid region over 50 K before crystallization was obtained in Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-Zr-M-B (M=Ti, Hf, V, Nb, Ta, Cr, Mo and W) systems and bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb, Ta)-(Mo, W)-B system by copper-mold casting. The ring-shaped glassy Fe-(Al, Ga)-(P, C, B, Si) alloys exhibit much better soft magnetic properties as compared with the ring-shaped alloy made from the melt-spun ribbon because of the formation of the unique domain structure. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk glassy magnetic material

  4. Shape Memory Alloy Actuator

    Science.gov (United States)

    Baumbick, Robert J. (Inventor)

    2002-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  5. Alloy catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...

  6. High strength ferritic alloy

    International Nuclear Information System (INIS)

    A high strength ferritic steel is specified in which the major alloying elements are chromium and molybdenum, with smaller quantities of niobium, vanadium, silicon, manganese and carbon. The maximum swelling is specified for various irradiation conditions. Rupture strength is also specified. (U.K.)

  7. Corrosion kinetics of alloy Ni-22Cr-13Mo-3W as structural material in high level nuclear waste containers

    International Nuclear Information System (INIS)

    Alloy Ni-22Cr-13Mo-3W (also known as C-22) is one of the candidates to fabricate high level nuclear waste containers. These containers are designed to maintain isolation of the waste for a minimum of 10,000 years. In this period, the material must be resistant to corrosion. If the containers were in contact with water, it is assumed that alloy C-22 may undergo three different corrosion mechanisms: general corrosion, localized corrosion and stress corrosion cracking. This thesis discusses only the first two types of degradation. Electrochemical techniques such as amperometry, potentiometry, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) and non-electrochemical techniques such as microscopic observation, X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS) were applied to study the corrosion behavior of alloy C-22 in 1 M NaCl, 25 C degrees saturated NaF (approximately 1 M) and 0,5 M NaCl + 0,5 M NaF solutions. Effects of temperature, pH and alloy thermal aging were analyzed. The corrosion rates obtained at 90 C degrees were low ranging from 0.04 μm/year to 0.48 μm /year. They increased with temperature and decreased with solution pH. Most of the impedance measurements showed a simply capacitive behavior. A second high-frequency time constant was detected in some cases. It was attributed to the formation of a nickel oxide and/or hydroxide at potentials near the reversible potential for this reaction. The active/passive transition detected in some potentiodynamic polarization curves was attributed to the same process. The corrosion potential showed an important increase after 24 hours of immersion. This increase in the corrosion potential was associated with an improvement of the passive film. The corrosion potential was always lower than the re-passivation potential for the corresponding media. The trans passive behavior of alloy C-22 was mainly influenced by temperature and solution chemistry. A clear trans passive peak

  8. Lattice thermal conductivity of multi-component alloys

    Energy Technology Data Exchange (ETDEWEB)

    Caro, M., E-mail: magda@lanl.gov [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Béland, L.K.; Samolyuk, G.D.; Stoller, R.E. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 54321 (United States); Caro, A. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2015-11-05

    High entropy alloys (HEA) have unique properties including the potential to be radiation tolerant. These materials with extreme disorder could resist damage because disorder, stabilized by entropy, is the equilibrium thermodynamic state. Disorder also reduces electron and phonon conductivity keeping the damage energy longer at the deposition locations, eventually favoring defect recombination. In the short time-scales related to thermal spikes induced by collision cascades, phonons become the relevant energy carrier. In this work, we perform a systematic study of phonon thermal conductivity in multiple component solid solutions represented by Lennard-Jones (LJ) potentials. We explore the conditions that minimize phonon mean free path via extreme alloy complexity, by varying the composition and the elements (differing in mass, atomic radii, and cohesive energy). We show that alloy complexity can be tailored to modify the scattering mechanisms that control energy transport in the phonon subsystem. Our analysis provides a qualitative guidance for the selection criteria used in the design of HEA alloys with low phonon thermal conductivity. - Highlights: • We show coupling between phonon scattering sources in multicomponent alloys. • We find criteria for combination of atomic masses and sizes to maximize scattering. • We show that more alloy components does not necessarily reduce conductivity.

  9. Halo formation in arc-melted Cr-Nb alloys

    Science.gov (United States)

    Li, K. W.; Li, S. M.; Xue, Y. L.; Fu, H. Z.

    2012-10-01

    Haloes of Laves phase Cr2Nb around the primary dendrites Cr were observed in the arc-melted Cr-12% Nb hypoeutectic alloy, while no halo of non-faceted Cr phase around the Cr2Nb Laves phase occurred in the Cr-20% Nb hypereutectic alloy. This observation differs from the haloes formed in metal-intermetallic alloy systems. An explanation on the formation of Cr2Nb halo was presented by considering the solidification behavior of the leading phase and non-reciprocal nucleation characteristics of the Cr2Nb/Cr eutectic. In the Cr-12% Nb alloy, primary dendrites Cr worked as a good nucleant available for the occurrence of the halo Cr2Nb that subsequently solidified as the leading phase in the eutectic. For the Cr-20% Nb alloy, primary dendrites Cr2Nb first precipitated as the leading phase inducing the eutectic formation, resulting in no halo growth. In addition, the coupled zone of the Cr-Nb alloy was theoretically predicted in agreement with the experimental results.

  10. The effects of low doses of 14 MeV neutrons on the properties of various commercial copper alloys

    International Nuclear Information System (INIS)

    Miniature tensile specimens of high purity copper and five copper alloys were irradiated with D-T fusion neutrons in the RTNS-II to fluences up to 2.5x1022 n/m2 at 900C and 2900C. The series of alloys includes solution-strengthened, precipitate-strengthened and dispersion-strengthened alloys. To compare fission and fusion neutron effects, some of the alloys were also irradiated at the same temperatures to similar damage levels of the Omega West Reactor. Tensile tests were performed at room temperature, and the radiation-induced changes in tensile properties are examined as functions of fluence and displacements per atom (dpa). All the alloys sustain less irradiation-induced strengthening than pure copper. In contrast to pure copper, the effects of fission and fusion neutrons on the yield stress changes in the copper alloys correlate well on the basis of dpa. (orig.)

  11. The effects of low doses of 14 MeV neutrons on the properties of various commercial copper alloys

    International Nuclear Information System (INIS)

    Miniature tensile specimens of high purity copper and five copper alloys were irradiated with D-T fusion neutrons in the RINS-II to fluences up to 2.5 x 1022 n/m2 at 90 and 2900C. The series of alloys includes solution-strengthened, precipitate-strengthened and dispersion-strengthened alloys. To compare fission and fusion neutron effects, some of the alloys were also irradiated at the same temperatures to similar damage levels in the Omega West Reactor. Tensile tests were performed at room temperature, and the radiation-induced changes in tensile properties are examined as functions of fluence and displacements per atom (dpa). All the alloys sustain less irradiation-induced strengthening than pure copper. In contrast to pure copper, the effects of fission and fusion neutrons on the yield stress changes in the copper alloys correlate well on the basis of dpa

  12. Deformation Properties of TiNi Shape Memory Alloy

    OpenAIRE

    Tobushi, H.; Lin, P.; K.Tanaka; Lexcellent, C.; Ikai, A

    1995-01-01

    In order to describe the deformation properties due to the martensitic transformation and the R-phase transformation of TiNi shape memory alloy, a thermomechanical constitutive equation considering the volume fractions of induced phases associated with both transformations is developed. The proposed constitutive equation expresses well the properties of the shape memory effect, pseudoelasticity and recovery stress.

  13. Thermally driven phase transformation on shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mielke, A. [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) im Forschungsverbund Berlin e.V. (Germany)]|[Humboldt-Universitaet, Berlin (Germany). Inst. fuer Mathematik; Petrov, A. [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) im Forschungsverbund Berlin e.V. (Germany)

    2007-07-01

    This paper analyzes a model for phase transformation in shape-memory alloys induced by temperature changes and by mechanical loading. We assume that the temperature is prescribed and formulate the problem within the framework of the energetic theory of rate-independent processes. Existence and uniqueness results are proved. (orig.)

  14. Effects of alloying elements on the formation of < c >-component loops in Zr alloy Excel under heavy ion irradiation.

    Energy Technology Data Exchange (ETDEWEB)

    Idrees, Yasir; Francis, Elisabeth M.; Yao, Zhongwen; Korinek, Andreas; Kirk, Marquis A.; Sattari, Mohammad; Preuss, Michael; Daymond, M. R.

    2015-05-14

    We report here the microstructural changes occurring in the zirconium alloy Excel (Zr-3.5 wt% Sn-0.8Nb-0.8Mo-0.2Fe) during heavy ion irradiation. In situ irradiation experiments were conducted at reactor operating temperatures on two Zr Excel alloy microstructures with different states of alloying elements, with the states achieved by different solution heat treatments. In the first case, the alloying elements were mostly concentrated in the beta (beta) phase, whereas, in the second case, large Zr-3(Mo,Nb,Fe)(4) secondary phase precipitates (SPPs) were grown in the alpha (alpha) phase by long term aging. The heavy ion induced damage and resultant compositional changes were examined using transmission electron microscopy (TEM) in combination with scanning transmission electron microscope (STEM)-energy dispersive x-ray spectroscopy (EDS) mapping. Significant differences were seen in microstructural evolution between the two different microstructures that were irradiated under similar conditions. Nucleation and growth of < c >-component loops and their dependence on the alloying elements are a major focus of the current investigation. It was observed that the < c >-component loops nucleate readily at 100, 300, and 400 degrees C after a threshold incubation dose (TID), which varies with irradiation temperature and the state of alloying elements. It was found that the TID for the formation of < c >-component loops increases with decrease in irradiation temperature. Alloying elements that are present in the form of SPPs increase the TID compared to when they are in the beta phase solid solution. Dose and temperature dependence of loop size and density are presented. Radiation induced redistribution and clustering of alloying elements (Sn, Mo, and Fe) have been observed and related to the formation of < c >-component loops. It has been shown that at the higher temperature tests, irradiation induced dissolution of precipitates occurs whereas irradiation induced

  15. The in-situ Ti alloying of aluminum alloys and its application in A356 alloys

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This research has investigated the in-situ Ti alloying of aluminum alloys and its application to A356 alloys and wheels through the evaluation of microstructure and mechanical properties, The results showed that stable titanium content can be obtained by adding a small quantity of TiO2 into electrolyte of pure aluminum. Under this approach, a greater than 95% absorptivity of titanium was achieved, and the microstructure of the specimens was changed to fine equiaxed grains from coarse columnar grains in the pure aluminum. In comparison with the tradition A356 alloys and wheels, the corresponding microstructure in the testing A356 alloys and wheels was finer. Although the tensile strength was similar between the testing and the tradition A356 alloys and wheels, the ductility of the former (testing) is superior to that of the later (tradition), leading to an excellent combination of strength and ductility from the testing alloys and wheels.

  16. Influence of alloyed Sc and Zr, and heat treatment on microstructures and stress corrosion cracking of Al–Zn–Mg–Cu alloys

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) behavior of Al–Zn–Mg–Cu alloys with different Sc, Zr contents and heat treatments was studied using slow strain rate test. Grain boundary microstructures were identified by transmission electron microscopy (TEM) and statistical analysis. It was found that the SCC resistance of alloys is improved by increasing Sc, Zr contents and aging degree. Grain boundary precipitates (GBPs) area fraction was found to be an important parameter to evaluate the SCC susceptibility. The results reveal that for Al–Zn–Mg–Cu–0.25Sc–0.10Zr (wt%) alloy with different aging degrees, hydrogen induced cracking dominates the SCC when the area fraction of GBPs is relatively low. For peak-aged Al–Zn–Mg–Cu alloy and Al–Zn–Mg–Cu–0.10Sc–0.10Zr (wt%) alloy, anodic dissolution dominates the SCC when the area fraction of GBPs is sufficiently high

  17. Influence of alloyed Sc and Zr, and heat treatment on microstructures and stress corrosion cracking of Al–Zn–Mg–Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yunjia [School of Materials Science and Engineering, Central South University, Hunan, Changsha 410083 (China); Pan, Qinglin, E-mail: csupql@163.com [School of Materials Science and Engineering, Central South University, Hunan, Changsha 410083 (China); Key Laboratory of Nonferrous Materials Science and Engineering of Ministry of Education, Hunan, Changsha 410083 (China); Li, Mengjia; Huang, Xing; Li, Bo [School of Materials Science and Engineering, Central South University, Hunan, Changsha 410083 (China)

    2015-01-05

    Stress corrosion cracking (SCC) behavior of Al–Zn–Mg–Cu alloys with different Sc, Zr contents and heat treatments was studied using slow strain rate test. Grain boundary microstructures were identified by transmission electron microscopy (TEM) and statistical analysis. It was found that the SCC resistance of alloys is improved by increasing Sc, Zr contents and aging degree. Grain boundary precipitates (GBPs) area fraction was found to be an important parameter to evaluate the SCC susceptibility. The results reveal that for Al–Zn–Mg–Cu–0.25Sc–0.10Zr (wt%) alloy with different aging degrees, hydrogen induced cracking dominates the SCC when the area fraction of GBPs is relatively low. For peak-aged Al–Zn–Mg–Cu alloy and Al–Zn–Mg–Cu–0.10Sc–0.10Zr (wt%) alloy, anodic dissolution dominates the SCC when the area fraction of GBPs is sufficiently high.

  18. Microstructure evolution of 7050 Al alloy during age-forming

    International Nuclear Information System (INIS)

    The microstructure evolution of the 7050 Al alloy treated by age-forming was studied using a designed device which can simulate the age-forming process. The grain shape, grain boundary misorientation and grain orientation evolution of 7050 Al alloy during age-forming have been quantitatively characterized by electron backscattering diffraction technique. The results show that age-forming produced abundant low-angle boundaries and elongated grains, which attributed to stress induced dislocation movement and grain boundary migration during the age-forming process. On the other side, the stress along rolling direction caused some unstable orientation grains to rotate towards the Brass and S orientations during the age-forming process. Hence, the intensity of the rolling texture orientation in age-formed samples is enhanced. But this effect decays gradually with increasing aging time, since stress decreases and precipitation hardening occurs during the age-forming process. - Highlights: • Quantitative analysis of grain evolution of 7050 Al alloys during age-forming • Stress induces some grain rotation of 7050 Al alloys during age-forming. • Creep leads to elongate grain of 7050 Al alloys during age-forming. • Obtains a trend on texture evolution during age-forming applied stress

  19. Inconvenient magnetocaloric effect in ferromagnetic shape memory alloys

    International Nuclear Information System (INIS)

    Highlights: ► Critical analysis of the available experimental results on isothermal magnetic entropy change in ferromagnetic shape memory alloys Ni–Mn–X (X = Ga, In, Sn, Sb) is given. ► Based on available in literature experimental data on total entropy change at martensitic transformation it is shown that the isothermal magnetic entropy change in Ni–Mn–X (X = Ga, In, Sn, Sb) should not greatly exceed 30 J/kg K. -- Abstract: Critical analysis available in the literature experimental results on magnetocaloric effect in ferromagnetic shape memory alloys Ni–Mn–X (X = Ga, In, Sn, Sb) is given. Based on a model developed by Pecharsky et al. [22], it is shown that the isothermal magnetic field-induced entropy change in the Ni–Mn–X alloys should not greatly exceed 30 J/kg K. Considering thermodynamics of temperature- and magnetic field-induced martensitic transformations, it is demonstrated that a contribution of the structural subsystem to the magnetocaloric effect in the Ni–Mn–X alloys studied so far is irreversible in magnetic fields below 5 T. This makes ferromagnetic shape memory alloys an inconvenient system for the practical application in modern magnetic refrigeration technology

  20. Alloy development and processing of FeAl: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, P.J.; Goodwin, G.M.; Alexander, D.J.; Viswanathan, S.

    1997-03-01

    In the last few years, considerable progress has been made in developing B2-phase FeAl alloys with improved weldability, room-temperature ductility, and high-temperature strength. Controlling the processing-induced microstructure is also important, particularly for minimizing trade-offs in various properties. FeAl alloys have outstanding resistance to high-temperature oxidation, sulfidation, and corrosion in various kinds of molten salts due to formation of protective Al{sub 2}O{sub 3} scales. Recent work shows that FeAl alloys are carburization-resistant as well. Alloys with 36 to 40 at. % Al have the best combination of corrosion resistance and mechanical properties. Minor alloying additions of Mo, Zr, and C, together with microalloying additions of B, produce the best combination of weldability and mechanical behavior. Cast FeAl alloys, with 200 to 400 {mu}m grain size and finely dispersed ZrC, have 2 to 5% tensile ductility in air at room-temperature, and a yield strength > 400 MPa up to about 700 to 750{degrees}C. Extruded ingot metallurgy (I/M) and powder metallurgy (P/M) materials with refined grain sizes ranging from 2 to 50 {mu}m, can have 10 to 15% ductility in air and be much stronger, and can even be quite tough, with Charpy impact energies ranging from 25 to 105 J at room-temperature. This paper highlights progress made in refining the alloy composition and exploring processing effects on FeAl for monolithic applications. It also includes recent progress on developing FeAl weld-overlay technology, and new results on welding of FeAl alloys. It summarizes some of the current industrial testing and interest for applications.