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Sample records for neutron-irradiated cr-mo ferritic

  1. Helium effects on neutron-irradiated Cr-Mo ferritic steels: A review of recent results

    SciTech Connect

    Klueh, R.L.; Maziasz, P.J.

    1988-01-01

    Large amounts of transmutation helium will be produced in the first wall of a fusion reactor by the high-energy neutrons from the fusion reaction. Since no fusion reactor is available, the effect of simultaneous helium production and displacement damage from neutron irradiation must be simulated. One method that has been used in ferritic steels is to add nickel to the steels and irradiate them in a mixed-spectrum reactor. In such reactors, the fast neutrons produce displacement damage, while helium is produced by a two-step reaction of /sup 58/Ni with thermal neutrons. This technique has been used to investigate the effect of helium on swelling, tensile properties, impact properties, and elevated-temperature embrittlement. Results indicate that helium accelerates swelling and affects tensile and impact properties of Cr-Mo ferritic steels below /approximately/450/degree/C. However, these steels are highly resistant to elevated-temperature helium embrittlement. 44 refs., 6 figs., 3 tabs.

  2. Mechanisms of Neutron Irradiation Hardening in Impurity-Doped Ferritic Alloys

    NASA Astrophysics Data System (ADS)

    Nishiyama, Y.; Liu, X. Y.; Kameda, J.

    2008-05-01

    Mechanisms of neutron irradiation hardening in phosphorus (P)-doped, sulfur (S)-doped, and copper (Cu)-doped ferritic alloys have been studied by applying a rate theory to the temperature dependence of the yield strength. Hardening behavior induced by neutron irradiation at various temperatures (473 to 711 K) is characterized in terms of the variations in athermal stress and activation energy for plasticity controlled by precipitation or solid solution, and kink-pair formation with the content and type of impurities. In P-doped alloys, neutron irradiation below 563 K brings about a remarkable increase in the athermal stress and activation energy, due to the dispersion of fine (˜1.7-nm) P-rich precipitates that is more extensive than that for the Cu-rich precipitates reported in irradiated steel. During neutron irradiation above 668 K, precipitation hardening occurs to some extent in Cu-doped and S-doped alloys, compared to small or negligible hardening in the P-doped alloys. In alloys with a low to moderate content of various dissolved impurities subjected to high-temperature irradiation, the formation of kink pairs becomes considerably difficult. Differing dynamic interactions of dissolved and precipitated impurities, i.e., P and Cu, with the nucleation and growth of dislocations are discussed, giving rise to irradiation hardening.

  3. Neutron irradiation effects on the ductile-brittle transition of ferritic/martensitic steels

    SciTech Connect

    Klueh, R.L.; Alexander, D.J.

    1997-08-01

    Ferritic/martensitic steels such as the conventional 9Cr-1MoVNb (Fe-9Cr-1Mo-0.25V-0.06Nb-0.1C) and 12Cr-1MoVW (Fe-12Cr-1Mo-0.25V-0.5W-0.5Ni-0.2C) steels have been considered potential structural materials for future fusion power plants. The major obstacle to their use is embrittlement caused by neutron irradiation. Observations on this irradiation embrittlement is reviewed. Below 425-450{degrees}C, neutron irradiation hardens the steels. Hardening reduces ductility, but the major effect is an increase in the ductile-brittle transition temperature (DBTT) and a decrease in the upper-shelf energy, as measured by a Charpy impact test. After irradiation, DBTT values can increase to well above room temperature, thus increasing the chances of brittle rather than ductile fracture.

  4. Microstructure and mechanical behavior of neutron irradiated ultrafine grained ferritic steel

    SciTech Connect

    Ahmad Alsabbagh; Apu Sarkar; Brandon Miller; Jatuporn Burns; Leah Squires; Douglas Porter; James I. Cole; K. L. Murty

    2014-10-01

    Neutron irradiation effects on ultra-fine grain (UFG) low carbon steel prepared by equal channel angular pressing (ECAP) has been examined. Counterpart samples with conventional grain (CG) sizes have been irradiated alongside with the UFG ones for comparison. Samples were irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) to 1.24 dpa. Atom probe tomography revealed manganese, silicon-enriched clusters in both ECAP and CG steel after neutron irradiation. X-ray quantitative analysis showed that dislocation density in CG increased after irradiation. However, no significant change was observed in UFG steel revealing better radiation tolerance.

  5. Low cycle fatigue properties of reduced activation ferritic/martensitic steels after high-dose neutron irradiation

    NASA Astrophysics Data System (ADS)

    Gaganidze, E.; Petersen, C.; Aktaa, J.; Povstyanko, A.; Prokhorov, V.; Diegele, E.; Lässer, R.

    2011-08-01

    This paper focuses on the low cycle fatigue (LCF) behaviour of reduced activation ferritic/martensitic steels irradiated to a displacement damage dose of up to 70 dpa at 330-337 °C in the BOR 60 reactor within the ARBOR 2 irradiation programme. The influence of neutron irradiation on the fatigue behaviour was determined for the as-received EUROFER97, pre-irradiation heat-treated EUROFER97 HT and F82H-mod steels. Strain-controlled push-pull loading was performed using miniaturized cylindrical specimens at a constant temperature of 330 °C with total strain ranges between 0.8% and 1.1%. Comparison of the LCF behaviour of irradiated and reference unirradiated specimens was performed for both the adequate total and inelastic strains. Neutron irradiation-induced hardening may have various effects on the fatigue behaviour of the steels. The reduction of inelastic strain in the irradiated state compared with the reference unirradiated state at common total strain amplitudes may increase fatigue lifetime. The increase in the stress at the adequate inelastic strain, by contrast, may accelerate fatigue damage accumulation. Depending on which of the two effects mentioned dominates, neutron irradiation may either extend or reduce the fatigue lifetime compared with the reference unirradiated state. The results obtained for EUROFER97 and EUROFER97 HT confirm these considerations. Most of the irradiated specimens show fatigue lifetimes comparable to those of the reference unirradiated state at adequate inelastic strains. Some irradiated specimens, however, show lifetime reduction or increase in comparison with the reference state at adequate inelastic strains.

  6. Relationship Between Grain Boundary Structure and Radiation Induced Segregation in a Neutron Irradiated 9 wt. % Cr Model Ferritic/Martensitic Steel

    SciTech Connect

    Field, Kevin G; Miller, Brandon; Chichester, Heather J.M.; Sridharan, K.; Allen, Todd R.

    2014-01-01

    Ferritic/Martensitic (F/M) steels with high Cr content posses the high temperature strength and low swelling rates required for advanced nuclear reactor designs. Radiation induced segregation (RIS) occurs in F/M steels due to solute atoms preferentially coupling to point defect fluxes to defect sinks, such as grain boundaries (GBs). The RIS response of F/M steels and austenitic steels has been shown to be dependent on the local structure of GBs but has only been demonstrated in ion irradiated specimens. A 9 wt. % Cr model alloy steel was irradiated to 3 dpa using neutrons at the Advanced Test Reactor (ATR) to determine the effect of neutron radiation environment on the RIS-GB structure dependence. This investigation found the relationship between GB structure and RIS is also active for F/M steels irradiated using neutrons. The data generated from the neutron irradiation is also compared to RIS data generated using proton irradiations on the same heat of model alloy.

  7. Relationship between lath boundary structure and radiation induced segregation in a neutron irradiated 9 wt.% Cr model ferritic/martensitic steel

    SciTech Connect

    Field, Kevin G.; Miller, Brandon D.; Chichester, Heather J. M.; Sridharan, Kumar; Allen, Todd R.

    2014-02-01

    Ferritic/Martensitic (F/M) steels with high Cr content posses the high temperature strength and low swelling rates required for advanced nuclear reactor designs. Radiation induced segregation (RIS) occurs in F/M steels due to solute atoms preferentially coupling to point defect fluxes which migrate to defect sinks, such as grain boundaries (GBs). The RIS response of F/M steels and austenitic steels has been shown to be dependent on the local structure of GBs where low energy structures have suppressed RIS responses. This relationship between local GB structure and RIS has been demonstrated primarily in ion-irradiated specimens. A 9 wt.% Cr model alloy steel was irradiated to 3 dpa using neutrons at the Advanced Test Reactor (ATR) to determine the effect of a neutron radiation environment on the RIS response at different GB structures. This investigation found the relationship between GB structure and RIS is also active for F/M steels irradiated using neutrons. The data generated from the neutron irradiation is also compared to RIS data generated using proton irradiations on the same heat of model alloy.

  8. Effect of neutron irradiation on vanadium alloys

    SciTech Connect

    Braski, D.N.

    1986-01-01

    Neutron-irradiated vanadium alloys were evaluated for their susceptibility to irradiation hardening, helium embrittlement, swelling, and residual radioactivity, and the results were compared with those for the austenitic and ferritic stainless steels. The VANSTAR-7 and V-15Cr-5Ti alloys showed the greatest hardening between 400 and 600/sup 0/C while V-3Ti-1Si and V-20Ti had lower values that were comparable to those of ferritic steels. The V-15Cr-5Ti and VANSTAR-7 alloys were susceptible to helium embrittlement caused by the combination of weakened grain boundaries and irradiation-hardened grain matrices. Specimen fractures were entirely intergranular in the most severe instances of embrittlement. The V-3Ti-1Si and V-20Ti alloys were more resistant to helium embrittlement. Except for VANSTAR-7 irradiated to 40 dpa at 520/sup 0/C, all of the vanadium alloys exhibited low swelling that was similar to the ferritic steels. Swelling was greater in specimens that were preimplanted with helium using the tritium trick. The vanadium alloys clearly exhibit lower residual radioactivity after irradiation than the ferrous alloys.

  9. Quantitative TEM analysis of precipitation and grain boundary segregation in neutron irradiated EUROFER 97

    NASA Astrophysics Data System (ADS)

    Dethloff, Christian; Gaganidze, Ermile; Aktaa, Jarir

    2014-11-01

    Characterization of irradiation induced microstructural defects is essential for assessing the applicability of structural steels like the Reduced Activation Ferritic/Martensitic steel EUROFER 97 in upcoming fusion reactors. In this work Transmission Electron Microscopy (TEM) is used to analyze the types and structure of precipitates, and the evolution of their size distributions and densities caused by neutron irradiation to a dose of 32 displacements per atom (dpa) at 330-340 °C in the irradiation experiment ARBOR 1. A significant growth of MX and M23C6 type precipitates is observed after neutron irradiation, while the precipitate density remains unchanged. Hardening caused by MX and M23C6 precipitate growth is assessed by applying the Dispersed Barrier Hardening (DBH) model, and shown to be of minor importance when compared to other irradiation effects like dislocation loop formation. Additionally, grain boundary segregation of chromium induced by neutron irradiation was investigated and detected in irradiated specimens.

  10. Interdiffusion in Ni/CrMo Composition-Modulated Films

    SciTech Connect

    Jankowski, A F; Saw, C K

    2003-02-18

    The measurement of diffusivity at low temperature in the Ni-CrMo alloy system, relative to the melt point, is accomplished through the use of a composition-modulated structure. The composition-modulated structure consists of numerous pairs of alternating Ni and Cr-Mo layers that are each just a few nanometers thick. A direct assessment of alloy stability is made possible through measurement of the atomic diffusion between these layers that occurs during anneal treatments. X ray diffraction under the Bragg condition in the {theta}/2{theta} mode is the method used to quantify the changes that occur in the short-range order, i.e. the artificial composition fluctuation. The relative intensities of satellite reflections about the Bragg peaks are monitored as a function of the time at temperature. The decay rate of the artificial composition fluctuation of Ni with Cr-Mo is analyzed using the microscopic theory of diffusion to quantify a macroscopic diffusion coefficient D as 1.52 x 10{sup -19} cm{sup 2} {center_dot} sec{sup -1} for Ni{sub 2}(Cr,Mo) at 760 K.

  11. Activity of enzyme immobilized on silanized Co-Cr-Mo.

    PubMed

    Puleo, D A

    1995-08-01

    The surface of an orthopedic biomaterial was modified by the covalent immobilization of biomolecules. Derivatization of Co-Cr-Mo samples with organic and aqueous solutions of gamma-aminopropyltriethoxysilane (APS) resulted in a concentration-dependent number of reactive NH2 groups on the surface available for coupling to protein. The enzyme trypsin was used as a model biomolecule to investigate the effect of immobilization on proteolytic activity. Trypsin was coupled to the silanized samples by formation of Schiff's base linkages via glutaraldehyde. The nature of the interaction between trypsin and biomaterial was then probed by treatment with concentrated guanidine hydrochloride (GuHCl) and urea. Residual activity (following treatment with chaotropic agents) of trypsin immobilized on silanized Co-Cr-Mo was dependent both on the nature of the silane solution and on the type of chaotropic agent. Organic silanization with APS required a minimum density of approximately 49 NH2 per nm2 of nominal surface area (> 0.021 M APS) for residual activity of immobilized trypsin. For aqueous silanization, approximately 5.4 NH2/nm2 (0.51 M APS) resulted in maximal residual trypsin activity. Treatment with GuHCl removed more trypsin activity from Co-Cr-Mo samples silanized with organic solutions of APS than did treatment with urea. On the contrary, with aqueous silanization the samples possessed greater residual activity following treatment with GuHCl than following urea. Compared to simple adsorption with protein onto Co-Cr-Mo, both methods of silanization with APS resulted in superior residual immobilized enzyme activity. PMID:7593038

  12. Albumin adsorption on CoCrMo alloy surfaces

    NASA Astrophysics Data System (ADS)

    Yan, Yu; Yang, Hongjuan; Su, Yanjing; Qiao, Lijie

    2015-12-01

    Proteins can adsorb on the surface of artificial joints immediately after being implanted. Although research studying protein adsorption on medical material surfaces has been carried out, the mechanism of the proteins’ adsorption which affects the corrosion behaviour of such materials still lacks in situ observation at the micro level. The adsorption of bovine serum albumin (BSA) on CoCrMo alloy surfaces was studied in situ by AFM and SKPFM as a function of pH and the charge of CoCrMo alloy surfaces. Results showed that when the specimens were uncharged, hydrophobic interaction could govern the process of the adsorption rather than electrostatic interaction, and BSA molecules tended to adsorb on the surfaces forming a monolayer in the side-on model. Results also showed that adsorbed BSA molecules could promote the corrosion process for CoCrMo alloys. When the surface was positively charged, the electrostatic interaction played a leading role in the adsorption process. The maximum adsorption occurred at the isoelectric point (pH 4.7) of BSA.

  13. Albumin adsorption on CoCrMo alloy surfaces

    PubMed Central

    Yan, Yu; Yang, Hongjuan; Su, Yanjing; Qiao, Lijie

    2015-01-01

    Proteins can adsorb on the surface of artificial joints immediately after being implanted. Although research studying protein adsorption on medical material surfaces has been carried out, the mechanism of the proteins’ adsorption which affects the corrosion behaviour of such materials still lacks in situ observation at the micro level. The adsorption of bovine serum albumin (BSA) on CoCrMo alloy surfaces was studied in situ by AFM and SKPFM as a function of pH and the charge of CoCrMo alloy surfaces. Results showed that when the specimens were uncharged, hydrophobic interaction could govern the process of the adsorption rather than electrostatic interaction, and BSA molecules tended to adsorb on the surfaces forming a monolayer in the side-on model. Results also showed that adsorbed BSA molecules could promote the corrosion process for CoCrMo alloys. When the surface was positively charged, the electrostatic interaction played a leading role in the adsorption process. The maximum adsorption occurred at the isoelectric point (pH 4.7) of BSA. PMID:26673525

  14. Total body calcium analysis. [neutron irradiation

    NASA Technical Reports Server (NTRS)

    Lewellen, T. K.; Nelp, W. B.

    1974-01-01

    A technique to quantitate total body calcium in humans is developed. Total body neutron irradiation is utilized to produce argon 37. The radio argon, which diffuses into the blood stream and is excreted through the lungs, is recovered from the exhaled breath and counted inside a proportional detector. Emphasis is placed on: (1) measurement of the rate of excretion of radio argon following total body neutron irradiation; (2) the development of the radio argon collection, purification, and counting systems; and (3) development of a patient irradiation facility using a 14 MeV neutron generator. Results and applications are discussed in detail.

  15. Effects of neutron irradiation on strength of fusion reactor materials and their electron beam welded joints

    NASA Astrophysics Data System (ADS)

    Kaga, S.; Tamura, T.; Yoshida, H.; Miyata, K.

    1991-03-01

    Several aluminum alloys (A7N01, A5083 and A6061) and a ferritic martensitic steel (JFMS) were used in the present study of the effects of neutron irradiation on the strength of base materials and their electron beam welded joints. Neutron irradiation tests were performed using the core irradiation facility at Kyoto University Reactor (KUR). Neutron fluences were 2.0 × 10 22 9.1 × 10 22 and 1.7 × 10 23n/ m2 ( E > 0.1 MeV). Tensile tests were performed at 4.2, 77 and 293 K on miniature specimens prepared from both the base and welded materials. Aluminum alloys exhibit serrations in the nominal stress-nominal strain curve at 4.2 K. Little effect of neutron irradiation on the serration is observed. The ductility decrease of base metal and welded joints of aluminum alloys by neutron irradiation is smaller than that of JFMS. JFMS, especially welded joints, showed strong radiation embrittlement at cryogenic temperatures.

  16. CoCrMo Metal-on-Metal Hip Replacements

    PubMed Central

    Liao, Yifeng; Hoffman, Emily; Wimmer, Markus; Fischer, Alfons; Jacobs, Joshua; Marks, Laurence

    2012-01-01

    After the rapid growth in the use of CoCrMo metal-on-metal hip replacements since the second generation was introduced circa 1990, metal-on-metal hip replacements have experienced a sharp decline in the last two years due to biocompatibility issues related to wear and corrosion products. Despite some excellent clinical results, the release of wear and corrosion debris and the adverse response of local tissues have been of great concern. There are many unknowns regarding how CoCrMo metal bearings interact with the human body. This perspective article is intended to outline some recent progresses in understanding wear and corrosion of metal-on-metal hip replacement both in-vivo and in-vitro. The materials, mechanical deformation, corrosion, wear-assisted corrosion, and wear products will be discussed. Possible adverse health effects caused by wear products will be briefly addressed, as well as some of the many open questions such as the detailed chemistry of corrosion, tribochemical reactions and the formation of graphitic layers. Nowadays we design almost routinely for high performance materials and lubricants for automobiles; humans are at least as important. It is worth remembering that a hip implant is often the difference between walking and leading a relatively normal life, and a wheelchair. PMID:23196425

  17. Z phase precipitation in martensitic 12CrMoVNb steels

    NASA Astrophysics Data System (ADS)

    Vodarek, V.; Strang, A.

    2003-10-01

    Precipitation of Z phase contributes significantly to degradation of creep properties of 12CrMoVNb steels because its precipitation is accompanied by dissolution offinely dispersed nitrides and carbonitrides of M2X and/or MX type. The orientation relationship between Z phase and the ferritic matrix was determined as: (001)_z// (001)_{α}, [010]_z // [010]_{α}. Prolonged thcrmal/creep exposure is accompanied by recrystallisation of the matrix and this orientation relationship is destroyed. Nevertheless Z phase particles preserve the form of thin plates. Z phase is a nitride which is rich in vanadium, niobium and chromium and its composition depends on both the temperature of precipitation and the initial chemical composition of steels. The composition of Z phase does not change during long term exposure at the original precipitation temperature. A relationship between the composition of Z phase and its temperature of formation may be able to be used as a temperature exposure indicator of steels. However it is also necessary to know the Z phase composition for a given cast of material.

  18. DECONTAMINATION OF NEUTRON-IRRADIATED REACTOR FUEL

    DOEpatents

    Buyers, A.G.; Rosen, F.D.; Motta, E.E.

    1959-12-22

    A pyrometallurgical method of decontaminating neutronirradiated reactor fuel is presented. In accordance with the invention, neutron-irradiated reactor fuel may be decontaminated by countercurrently contacting the fuel with a bed of alkali and alkaine fluorides under an inert gas atmosphere and inductively melting the fuel and tracking the resulting descending molten fuel with induction heating as it passes through the bed. By this method, a large, continually fresh surface of salt is exposed to the descending molten fuel which enhances the efficiency of the scrubbing operation.

  19. The stability of DLC film on nitrided CoCrMo alloy in phosphate buffer solution

    NASA Astrophysics Data System (ADS)

    Zhang, T. F.; Liu, B.; Wu, B. J.; Liu, J.; Sun, H.; Leng, Y. X.; Huang, N.

    2014-07-01

    CoCrMo alloy is often used as the material for metal artificial joint, but metal debris and metal ions are the main concern on tissue inflammation or tissue proliferation for metal prosthesis. In this paper, nitrogen ion implantation and diamond like carbon (DLC) film composite treatment was used to reduce the wear and ion release of biomedical CoCrMo substrate. The mechanical properties and stability of N-implanted/DLC composite layer in phosphate buffer solution (PBS) was evaluated to explore the full potential of N-implanted/DLC composite layer as an artificial joint surface modification material. The results showed that the DLC film on N implanted CoCrMo (N-implanted/DLC composite layer) had the higher surface hardness and wear resistance than the DLC film on virgin CoCrMo alloy, which was resulted from the strengthen effect of the N implanted layer on CoCrMo alloy. After 30 days immersion in PBS, the structure of DLC film on virgin CoCrMo or on N implanted CoCrMo had no visible change. But the adhesion and corrosion resistance of DLC on N implanted CoCrMo (N-implanted/DLC composite layer) was weakened due to the dissolution of the N implanted layer after 30 days immersion in PBS. The adhesion reduction of N-implanted/DLC composite layer was adverse for in vivo application in long term. So researcher should be cautious to use N implanted layer as an inter-layer for increasing CoCrMo alloy load carrying capacity in vivo environment.

  20. Subtask 12F1: Effect of neutron irradiation on swelling of vanadium-base alloys

    SciTech Connect

    Chung, H.M.; Loomis, B.A.; Smith, D.L.

    1995-03-01

    The objective of this work is to determine the effects of neutron irradiation on the density change, void distribution, and microstructural evolution of vanadium-base alloys. Swelling behavior and microstructural evolution of V-Ti, V-Cr-Ti, and V-Ti-Si alloys were investigated after irradiation at 420-600{degrees}C up to 114 dpa. The alloys exhibited swelling maxima between 30 and 80 dpa and swelling decreased on irradiation to higher dpa. This is in contrast to the monotonically increasing swelling of binary alloys that contain Fe, Ni, Cr, Mo, W, and Si. Precipitation of dense Ti{sub 5}Si{sub 3} promotes good resistance to swelling of the Ti-containing alloys, and it was concluded that Ti of >3 wt.% and 400-1000 wppm Si are necessary to effectively suppress swelling. Swelling was minimal in V-4Cr-4Ti, identified as the most promising alloy based on good mechanical properties and superior resistance to irradiation embrittlement. 18 refs., 6 figs., 1 tab.

  1. Electrochemical Testing of Ni-Cr-Mo-Gd Alloys

    SciTech Connect

    T. E. Lister; R. E. Mizia; H. Tian

    2005-10-01

    The waste package site recommendation design specified a boron-containing stainless steel, Neutronit 976/978, for fabrication of the internal baskets that will be used as a corrosion-resistant neutron-absorbing material. Recent corrosion test results gave higher-than-expected corrosion rates for this material. The material callout for these components has been changed to a Ni-Cr-Mo-Gd alloy (ASTM-B 932-04, UNS N06464) that is being developed at the Idaho National Laboratory. This report discusses the results of initial corrosion testing of this material in simulated in-package environments that could contact the fuel baskets after breach of the waste package outer barrier. The corrosion test matrix was executed using the potentiodynamic and potentiostatic electrochemical test techniques. The alloy performance shows low rates of general corrosion after initial removal of a gadolinium-rich second phase that intersects the surface. The high halide-containing test solutions exhibited greater tendencies toward initiation of crevice corrosion.

  2. Evolution of the mechanical properties and microstructure of ferritic-martensitic steels irradiated in the BOR-60 reactor

    NASA Astrophysics Data System (ADS)

    Shamardin, V. K.; Golovanov, V. N.; Bulanova, T. M.; Povstyanko, A. V.; Fedoseev, A. E.; Ostrovsky, Z. E.; Goncharenko, Yu. D.

    2002-12-01

    The effect of neutron irradiation on mechanical properties of low-activation ferritic-martensitic (FM) steels 0.1C-9Cr-1W, V, Ta, B and 0.1C-12Cr-2W, V, Ti, B is studied under tension at temperatures of 330-540 °C and doses of 50 dpa. Steel 0.1C-13Cr-Mo, V, Nb, B was chosen for comparison. At irradiation temperatures of 330-340 °C, the radiation hardening of steel with 9%Cr achieves saturation at a dose of 10 dpa. In this case as compared to steels with 12%Cr, the fracture surface is characterized as ductile without cleavage traces. At irradiation temperatures higher than 420 °C, there is no difference in the behavior of the materials under investigation. The data on radiation creep obtained by direct measurement and from the profilometry data satisfy a model ɛ¯/ σ¯=B 0+D Ṡ, when B0 and D have the values typical for steels of FM type.

  3. Neutron irradiation induced amorphization of silicon carbide

    SciTech Connect

    Snead, L.L.; Hay, J.C.

    1998-09-01

    This paper provides the first known observation of silicon carbide fully amorphized under neutron irradiation. Both high purity single crystal hcp and high purity, highly faulted (cubic) chemically vapor deposited (CVD) SiC were irradiated at approximately 60 C to a total fast neutron fluence of 2.6 {times} 10{sup 25} n/m{sup 2}. Amorphization was seen in both materials, as evidenced by TEM, electron diffraction, and x-ray diffraction techniques. Physical properties for the amorphized single crystal material are reported including large changes in density ({minus}10.8%), elastic modulus as measured using a nanoindentation technique ({minus}45%), hardness as measured by nanoindentation ({minus}45%), and standard Vickers hardness ({minus}24%). Similar property changes are observed for the critical temperature for amorphization at this neutron dose and flux, above which amorphization is not possible, is estimated to be greater than 130 C.

  4. TEM study of neutron-irradiated iron

    SciTech Connect

    Horton, L.L.; Bentley, J.; Farrell, K.

    1981-01-01

    Results of a transmission electron microscopy study of the defect structure in iron neutron-irradiated to low fluences (less than or equal to 1 dpa) at temperatures of 455 to 1013/sup 0/K are presented. The dislocation microstructures coarsen with increasing irradiation temperature from decorated dislocations, through clusters of dislocation loops, to near-edge, interstitial dislocation loops with b = a<100>, and network segments. Significant cavity formation occurred only at 548 to 723/sup 0/K, with homogeneous distributions found only at 623 and 673/sup 0/K. The maximum swelling of 0.07% occurred at 673/sup 0/K. Large cavities had a truncated octahedral shape with (111) facets and (100) truncations. Damage halos were observed around boron-containing precipitates. The effects of interstitial impurities on microstructural development and the differences in the observed microstructures compared to those in refractory bcc metals are discussed. 8 figures, 6 tables.

  5. Environmentally Assisted Cracking of Commercial Ni-Cr-Mo Alloys - A Review

    SciTech Connect

    Rebak, R B

    2004-11-09

    Nickel-Chromium-Molybdenum alloys (Ni-Cr-Mo) are highly resistant to general corrosion, localized corrosion and environmentally assisted cracking (EAC). Cr acts as a beneficial element under oxidizing acidic conditions and Mo under reducing conditions. All three elements (Ni, Cr and Mo) act synergistically to provide resistance to EAC in environments such as hot concentrated chloride solutions. Ni-Cr-Mo alloys may suffer EAC in environments such as hot caustic solutions, hot wet hydrofluoric acid (HF) solutions and in super critical water oxidation (SCWO) applications. Not all the Ni-Cr-Mo alloys have the same susceptibility to cracking in the mentioned environments. Most of the available data regarding EAC is for the oldest Ni-Cr-Mo alloys such as N10276 and N06625.

  6. A separation of protactinium from neutron-irradiated thorium.

    PubMed

    Lyle, S J; Shendrikar, A D

    1966-01-01

    A convenient-method, based on liquid-liquid extraction with N-benzoyl-N-phenylhydroxylamine in chloroform, is given for the separation of protactinium-233 from neutron-irradiated thorium. PMID:18959855

  7. PROCESSING OF NEUTRON-IRRADIATED URANIUM

    DOEpatents

    Hopkins, H.H. Jr.

    1960-09-01

    An improved "Purex" process for separating uranium, plutonium, and fission products from nitric acid solutions of neutron-irradiated uranium is offered. Uranium is first extracted into tributyl phosphate (TBP) away from plutonium and fission products after adjustment of the acidity from 0.3 to 0.5 M and heating from 60 to 70 deg C. Coextracted plutonium, ruthenium, and fission products are fractionally removed from the TBP by three scrubbing steps with a 0.5 M nitric acid solution of ferrous sulfamate (FSA), from 3.5 to 5 M nitric acid, and water, respectively, and the purified uranium is finally recovered from the TBP by precipitation with an aqueous solution of oxalic acid. The plutonium in the 0.3 to 0.5 M acid solution is oxidized to the tetravalent state with sodium nitrite and extracted into TBP containing a small amount of dibutyl phosphate (DBP). Plutonium is then back-extracted from the TBP-DBP mixture with a nitric acid solution of FSA, reoxidized with sodium nitrite in the aqueous strip solution obtained, and once more extracted with TBP alone. Finally the plutonium is stripped from the TBP with dilute acid, and a portion of the strip solution thus obtained is recycled into the TBPDBP for further purification.

  8. Weldability of neutron irradiated austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Asano, Kyoichi; Nishimura, Seiji; Saito, Yoshiaki; Sakamoto, Hiroshi; Yamada, Yuji; Kato, Takahiko; Hashimoto, Tsuneyuki

    1999-01-01

    Degradation of weldability in neutron irradiated austenitic stainless steel is an important issue to be addressed in the planning of proactive maintenance of light water reactor core internals. In this work, samples selected from reactor internal components which had been irradiated to fluence from 8.5 × 10 22 to 1.4 × 10 26 n/m 2 ( E > 1 MeV) corresponding to helium content from 0.11 to 103 appm, respectively, were subjected to tungsten inert gas arc (TIG) welding with heat input ranged 0.6-16 kJ/cm. The weld defects were characterized by penetrant test and cross-sectional metallography. The integrity of the weld was better when there were less helium and at lower heat input. Tensile properties of weld joint containing 0.6 appm of helium fulfilled the requirement for unirradiated base metal. Repeated thermal cycles were found to be very hazardous. The results showed the combination of material helium content and weld heat input where materials can be welded with little concern to invite cracking. Also, the importance of using properly selected welding procedures to minimize thermal cycling was recognized.

  9. Influence of carbides and microstructure of CoCrMo alloys on their metallic dissolution resistance.

    PubMed

    Valero-Vidal, C; Casabán-Julián, L; Herraiz-Cardona, I; Igual-Muñoz, A

    2013-12-01

    CoCrMo alloys are passive and biocompatible materials widely used as joint replacements due to their good mechanical properties and corrosion resistance. Electrochemical behaviour of thermal treated CoCrMo alloys with different carbon content in their bulk alloy composition has been analysed. Both the amount of carbides in the CoCrMo alloys and the chemical composition of the simulated body fluid affect the electrochemical properties of these biomedical alloys, thus passive dissolution rate was influenced by the mentioned parameters. Lower percentage of carbon in the chemical composition of the bulk alloy and thermal treatments favour the homogenization of the surface (less amount of carbides), thus increasing the availability of Cr to form the oxide film and improving the corrosion resistance of the alloy. PMID:24094174

  10. Laser annealing of neutron irradiated boron-10 isotope doped diamond

    SciTech Connect

    Jagannadham, K.; Butler, J. E.

    2011-01-01

    10B isotope doped p-type diamond epilayer grown by chemical vapor deposition on (110) oriented type IIa diamond single crystal substrate was subjected to neutron transmutation at a fluence of 2.4 9 1020 thermal and 2.4 9 1020 fast neutrons. After neutron irradiation, the epilayer and the diamond substrate were laser annealed using Nd YAG laser irradiation with wave length, 266 nm and energy, 150 mJ per pulse. The neutron irradiated diamond epilayer and the substrate were characterized before and after laser annealing using different techniques. The characterization techniques include optical microscopy, secondary ion mass spectrometry, X-ray diffraction, Raman, photoluminescence and Fourier Transform Infrared spectroscopy, and electrical sheet conductance measurement. The results indicate that the structure of the irradiation induced amorphous epilayer changes to disordered graphite upon laser annealing. The irradiated substrate retains the (110) crystalline structure with neutron irradiation induced defects.

  11. Proton and neutron irradiation effect of Ti: Sapphires

    SciTech Connect

    Wang, G.; Zhang, J.; Yang, J.

    1999-07-01

    Various effects of proton and neutron irradiated Ti: sapphires were studied. Proton irradiation induced F, F{sup +} and V center in Ti: sapphires and 3310 cm{sup -1} infrared absorption, and made ultraviolet absorption edge shift to short wave. Neutron irradiation produced a number of F, F{sup +} and F{sub 2} centers and larger defects in Ti: sapphires, and changed Ti{sup 4+}into Ti{sup 3+} ions. Such valence state variation enhanced characteristic luminescence of Ti: sapphires, and no singular variances of intrinsic fluorescence spectra of Ti: sapphires took place with neutron flux of 1 x 10{sup 17}n/cm{sup 2}, but the fluorescence vanished with neutron flux of 1 x 10{sup 18}n/cm{sup 2} which means the threshold for the concentration of improving Ti{sup 3+} ions by neutron irradiation.

  12. New facility for post irradiation examination of neutron irradiated beryllium

    SciTech Connect

    Ishitsuka, Etsuo; Kawamura, Hiroshi

    1995-09-01

    Beryllium is expected as a neutron multiplier and plasma facing materials in the fusion reactor, and the neutron irradiation data on properties of beryllium up to 800{degrees}C need for the engineering design. The acquisition of data on the tritium behavior, swelling, thermal and mechanical properties are first priority in ITER design. Facility for the post irradiation examination of neutron irradiated beryllium was constructed in the hot laboratory of Japan Materials Testing Reactor to get the engineering design data mentioned above. This facility consist of the four glove boxes, dry air supplier, tritium monitoring and removal system, storage box of neutron irradiated samples. Beryllium handling are restricted by the amount of tritium;7.4 GBq/day and {sup 60}Co;7.4 MBq/day.

  13. Characterizing the spheroidization grade and strength of 15CrMo steel through determining fractal dimension

    NASA Astrophysics Data System (ADS)

    Liu, Changjun; Dong, Leiyun; Jiang, Xiaodong

    2012-07-01

    The fractal dimension (FD) of surfaces has been widely used to characterize the properties of materials. However, most of the previous researches were concentrated on the correlation between the FD of surfaces and mechanical properties of materials, such as impact energy and fracture toughness, etc. The aim of this paper is to characterize the spheroidization grade and strength of 15CrMo steel through determination of FD of cementite phase on the basis of two-dimension microstructural image. Two methods, namely slit-island method (SIM) and box-counting method (BCM), are used to determine the value of FD. It is found that the FD value evaluated by using BCM is generally higher than that evaluated by SIM. This phenomenon may be due to the difference in the principles used in different methods. Whether SIM or BCM is used, the spheroidization grade in 15CrMo steel linearly increases with decreasing the value of FD. The relationship between the FD value, D, and spheroidization grade, S g, can be approximately expressed as D≌-0.11 S g+ A, where A is a constant value which is depended on the evaluation method. Both the ultimate strength and the yielding strength of 15CrMo steel increase with increasing FD of cementite phase. There may be a common relationship between the FD of cementite phase and strength of 15CrMo steel. When the FD of cementite phase in 15CrMo steel is determined, the strength of this steel can be evaluated. The present paper can provide a novel method to evaluate the strength and spheroidization grade of carbon steel through determination of fractal dimension (FD) of cementite phase.

  14. Friction, lubrication, and polymer transfer between UHMWPE and CoCrMo hip-implant materials: a fluorescence microscopy study.

    PubMed

    Crockett, Rowena; Roba, Marcella; Naka, Marco; Gasser, Beat; Delfosse, Daniel; Frauchiger, Vinzenz; Spencer, Nicholas D

    2009-06-15

    The friction coefficients of CoCrMo sliding against UHMWPE and CoCrMo were measured in solutions of albumin and synovial fluid containing fluorescently labeled albumin. No fluorescence could be observed on the CoCrMo disc following incubation in labeled albumin or after sliding against CoCrMo. This was due to quenching of the fluorophore by the metal and indicated that a protein film thicker than 10 nm was not formed on the surface. A more complicated behavior was observed for UHMWPE sliding against CoCrMo. For each lubricating solution and at each load, a bimodal distribution of steady-state friction values was observed, the friction coefficient either remaining constant or decreasing during the early stages of the measurement. As no quenching of the fluorophores occurred on the UHMWPE surface, the fluorescence labeling method could be used to reveal polyethylene (PE) transfer and to show that it correlates with the friction coefficient: Low friction coefficients corresponded to a low density of PE spots on the CoCrMo surface. In addition, it was found that the friction coefficients for UHMWPE sliding against CoCrMo in synovial fluid were not significantly different from those in phosphate-buffered saline (PBS), but that the addition of albumin to PBS did cause a significant increase in the friction coefficient.

  15. Bovine Serum Albumin binding to CoCrMo nanoparticles and the influence on dissolution

    NASA Astrophysics Data System (ADS)

    Simoes, T. A.; Brown, A. P.; Milne, S. J.; Brydson, R. M. D.

    2015-10-01

    CoCrMo alloys exhibit good mechanical properties, excellent biocompatibility and are widely utilised in orthopaedic joint replacements. Metal-on-metal hip implant degradation leads to the release of metal ions and nanoparticles, which persist through the implant's life and could be a possible cause of health complications. This study correlates preferential binding between proteins and metal alloy nanoparticles to the alloy's corrosion behaviour and the release of metal ions. TEM images show the formation of a protein corona in all particles immersed in albumin containing solutions. Only molybdenum release was significant in these tests, suggesting high dissolution of this element when CoCrMo alloy nanoparticles are produced as wear debris in the presence of serum albumin. The same trend was observed during extended exposure of molybdenum reference nanoparticles to albumin.

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

    SciTech Connect

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

    2006-07-07

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

  17. Numerical Simulation on Optimization of Center Segregation for 50CrMo Structural Alloy Steel

    NASA Astrophysics Data System (ADS)

    Gao, Xiangzhou; Yang, Shufeng; Li, Jingshe; Liao, Hang

    2016-06-01

    To improve the center segregation of billet for 50CrMo structural alloy steel, a 3D numerical model of solidification and heat transfer process for continuous casting had been established. The influence law of continuous casting process parameters on the secondary dendrite arm spacing (SDAS) and equiaxed crystal ratio had been obtained. It was shown that reducing superheat and casting speed and increasing the secondary cooling intensity could decrease SDAS. Reducing any one of the three parameters could increase the equiaxed crystal ratio. Adjusting only secondary cooling intensity could not make the SDAS and equiaxed crystal ratio change in the desired direction, but regulating the other two parameters could supply this gap. After optimizing the continuous casting process parameters of 50CrMo billet, the defect of center segregation was solved basically.

  18. [Use of powder metallurgy for development of implants of Co-Cr-Mo alloy powder].

    PubMed

    Dabrowski, J R

    2001-04-01

    This paper discusses the application of powder metallurgy for the development of porous implantation materials. Powders obtained from Co-Cr-Mo alloy with different carbon content by water spraying and grinding, have been investigated. Cold pressing and rotary re-pressing methods were used for compressing the powder. It was found that the sintered materials obtained from water spraying have the most advantageous properties. PMID:11388037

  19. Mechanism and kinetics of interaction of Fe, Cr, Mo, and Mn atoms with molecular oxygen

    SciTech Connect

    Akhmadov, U.S.; Zaslonko, I.S.; Smirnov, V.N.

    1988-09-01

    By means of resonance atomic absorption in shock waves, rate constants have been measured for the interaction of atoms of a number of transition metals (Fe, Cr, Mo, and Mn) with molecular oxygen. A new method is proposed and used for determining the exponent ..gamma.. in the modified Lambert-Beer law D = element of(ZN)/sup ..gamma../. The bond strength in CrO and MoO molecules has been estimated.

  20. Magnetism in Sr2CrMoO6 : A combined ab initio and model study

    NASA Astrophysics Data System (ADS)

    Sanyal, Prabuddha; Halder, Anita; Si, Liang; Wallerberger, Markus; Held, Karsten; Saha-Dasgupta, Tanusri

    2016-07-01

    Using a combination of first-principles density functional theory (DFT) calculations and exact diagonalization studies of a first-principles derived model, we carry out a microscopic analysis of the magnetic properties of the half-metallic double perovskite compound Sr2CrMoO6 , a sister compound of the much discussed material Sr2FeMoO6 . The electronic structure of Sr2CrMoO6 , though appearing similar to Sr2FeMoO6 at first glance, shows nontrivial differences with that of Sr2FeMoO6 on closer examination. In this context, our study highlights the importance of charge transfer energy between the two transition metal sites. The change in charge transfer energy due to a shift of Cr d states in Sr2CrMoO6 compared to Fe d in Sr2FeMoO6 suppresses the hybridization between Cr t2 g and Mo t2 g. This strongly weakens the hybridization-driven mechanism of magnetism discussed for Sr2FeMoO6 . Our study reveals that, nonetheless, the magnetic transition temperature of Sr2CrMoO6 remains high since an additional superexchange contribution to magnetism arises with a finite intrinsic moment developed at the Mo site. We further discuss the situation in comparison to another related double perovskite compound, Sr2CrWO6 . We also examine the effect of correlation beyond DFT, using dynamical mean field theory.

  1. Control of surface morphology of carbide coating on Co-Cr-Mo implant alloy.

    PubMed

    Vandamme, N S; Topoleski, L D T

    2005-07-01

    Wear of materials used in artificial joints is a common failure mode of artificial joints. A low wear rate for implants is believed to be critical for extending implant service time. We developed a carbide-coated Co-Cr-Mo implant alloy created in plasma of methane and hydrogen mixed gas by a microwave plasma-assisted surface reaction. The carbide-coated Co-Cr-Mo has a unique "brain coral-like" surface morphology and is much harder than uncoated Co-Cr-Mo. The effect of plasma processing time and temperature on the surface morphology of the top carbide layer was studied toward optimizing the surface coating. The ratios of average roughness, Ra, core roughness, Rk, and summation of core roughness, reduced peak height (Rpk) and reduced valley depth (Rvk), Rk+Rpk+Rvk, for the 6-h/985 degrees C coating to those for the 0.5-h/985 degrees C coating were 1.9, 1.7, and 1.9, respectively. The ratios of Ra, Rk, and Rk+Rpk+Rvk for the 4-h/1000 degrees C coating to those for the 4-h/939 degrees C coating were 2.3, 2.3, and 2.0, respectively. With the proper combination of plasma processing time and temperature, it may be possible to change the thickness of the peak-valley top cluster by fourfold from approximately 0.6 microm to approximately 2.5 microm. Finally, the growth mechanism of the carbide layers on Co-Cr-Mo was discussed in the context of atomic composition analysis. PMID:15965597

  2. Precipitation behavior of BN type inclusions in 42CrMo steel

    NASA Astrophysics Data System (ADS)

    Wang, Yu-nan; Bao, Yan-ping; Wang, Min; Zhang, Le-chen

    2013-01-01

    Automobile crankshaft steel 42CrMo, which requires excellent machinability and mechanical properties, cannot be manufactured by traditional methods. To achieve these qualities, the formation behavior of boron nitride (BN) inclusions in 42CrMo steel was studied in this article. First, the precipitation temperature and the amount of BN type inclusions with different contents of boron and nitrogen in molten steel were calculated thermodynamically by FactSage software. Then the morphology and the size of BN type inclusions as well as the influence of cooling methods on them were investigated by scanning electron microscopy. Furthermore, the effects of cooling rate and the contents of B and N in molten steel on the morphology, size, and distribution of BN type inclusions were studied quantitatively and detailedly by directional solidification experiments. It is found that different BN inclusions in molten steel can form by controlling the cooling rate and the contents of B and N, which is important for obtaining the excellent machinability of 42CrMo steel.

  3. Radiation Damage Study in Natural Zircon Using Neutrons Irradiation

    SciTech Connect

    Lwin, Maung Tin Moe; Amin, Yusoff Mohd.; Kassim, Hasan Abu; Mohamed, Abdul Aziz; Karim, Julia Abdul

    2011-03-30

    Changes of atomic displacements in crystalline structure of natural zircon (ZrSiO{sub 4}) can be studied by using neutron irradiation on the surface of zircon and compared the data from XRD measurements before and after irradiation. The results of neutron irradiation on natural zircon using Pneumatic Transfer System (PTS) at PUSPATI TRIGA Research Reactor in the Malaysian Nuclear Agency are discussed in this work. The reactor produces maximum thermal power output of 1 MWatt and the neutron flux of up to 1x10{sup 13} ncm{sup -2}s{sup -1}. From serial decay processes of uranium and thorium radionuclides in zircon crystalline structure, the emission of alpha particles can produce damage in terms of atomic displacements in zircon. Hence, zircon has been extensively studied as a possible candidate for immobilization of fission products and actinides.

  4. Neutron irradiation effects on high Nicalon silicon carbide fibers

    SciTech Connect

    Osborne, M.C.; Steiner, D.; Snead, L.L.

    1996-10-01

    The effects of neutron irradiation on the mechanical properties and microstructure of SiC and SiC-based fibers is a current focal point for the development of radiation damage resistant SiC/SiC composites. This report discusses the radiation effects on the Nippon Carbon Hi-Nicalon{trademark} fiber system and also discusses an erratum on earlier results published by the authors on this material. The radiation matrix currently under study is also summarized.

  5. Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites

    SciTech Connect

    Newsome G, Snead L, Hinoki T, Katoh Y, Peters D

    2007-03-26

    The effects of fast neutron irradiation on SiC and SiC composites have been studied. The materials used were chemical vapor deposition (CVD) SiC and SiC/SiC composites reinforced with either Hi-Nicalon{trademark} Type-S, Hi-Nicalon{trademark} or Sylramic{trademark} fibers fabricated by chemical vapor infiltration. Statistically significant numbers of flexural samples were irradiated up to 4.6 x 10{sup 25} n/m{sup 2} (E>0.1 MeV) at 300, 500 and 800 C in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Dimensions and weights of the flexural bars were measured before and after the neutron irradiation. Mechanical properties were evaluated by four point flexural testing. Volume increase was seen for all bend bars following neutron irradiation. Magnitude of swelling depended on irradiation temperature and material, while it was nearly independent of irradiation fluence over the fluence range studied. Flexural strength of CVD SiC increased following irradiation depending on irradiation temperature. Over the temperature range studied, no significant degradation in mechanical properties was seen for composites fabricated with Hi-Nicalon{trademark} Type-S, while composites reinforced with Hi-Nicalon{trademark} or Sylramic fibers showed significant degradation. The effects of irradiation on the Weibull failure statistics are also presented suggesting a reduction in the Weibull modulus upon irradiation. The cause of this potential reduction is not known.

  6. Effects of Fast Neutron Irradiation on Zirconium Carbide

    SciTech Connect

    Snead, Lance Lewis; Katoh, Yutai; Kondo, Sosuke

    2010-01-01

    High-purity zone refined zirconium carbide has been fast neutron irradiated in the dose and temperature range of 1-10 x 10{sup 25} N/m{sup 2} (E > 0.1 MeV) and 635-1480 C, respectively. Non-irradiated and as-irradiated properties were measured including the lattice parameter, hardness and elastic modulus as determined through nano-indentation, thermal conductivity, and indentation fracture toughness. The effects of neutron irradiation on the microstructure were also determined though using transmission electron microscopy. The general finding of this paper, limited to this particular zone refined ZrC of nominal C/Zr ratio of 0.93, is that this ceramic is quite stable under neutron irradiation in the temperature and dose range studied. Measurement of lattice parameter before and after irradiation indicated a lack of significant crystalline strain due to irradiation. Only modest changes were observed in the mechanical properties of hardness, elastic modulus, and indentation fracture toughness. The thermal conductivity underwent a slight reduction near 1000 C irradiation, though was essentially unchanged for 1300-1480 C irradiation. Transmission electron microscopy revealed black-spot-type defects (likely Frank or other small loops) for irradiation at 670 C, maturing to faulted Frank loops at 1280 C. As the irradiation temperature increased from 1280 C to the highest irradiation temperature, of 1496 C, a transition to prismatic loops occurs.

  7. Radiation Damages in Aluminum Alloy SAV-1 under Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Salikhbaev, Umar; Akhmedzhanov, Farkhad; Alikulov, Sherali; Baytelesov, Sapar; Boltabaev, Azizbek

    2016-05-01

    The aim of this work was to study the effect of neutron irradiation on the kinetics of radiation damages in the SAV-1 alloy, which belongs to the group of aluminum alloys of the ternary system Al-Mg-Si. For fast-neutron irradiation by different doses up to fluence 1019 cm-2 the SAV-1 samples were placed in one of the vertical channels of the research WWR type reactor (Tashkent). The temperature dependence of the electrical resistance of the alloy samples was investigated in the range 290 - 490 K by the four-compensation method with an error about 0.1%. The experimental results were shown that at all the temperatures the dependence of the SAV-1 alloy resistivity on neutron fluence was nonlinear. With increasing neutron fluence the deviation from linearity and the growth rate of resistivity with temperature becomes more appreciable. The observed dependences are explained by means of martensitic transformations and the radiation damages in the studied alloy under neutron irradiation. The mechanisms of radiation modification of the SAV-1 alloy structure are discussed.

  8. Mesenchymal stem cell response to topographically modified CoCrMo.

    PubMed

    Logan, Niall; Bozec, Laurent; Traynor, Alison; Brett, Peter

    2015-12-01

    Surface roughness on implant materials has been shown to be highly influential on the behavior of osteogenic cells. Four surface topographies were engineered on cobalt chromium molybdenum (CoCrMo) in order to examine this influence on human mesenchymal stem cells (MSC). These treatments were smooth polished (SMO), acid etched (AE) using HCl 7.4% and H2SO4 76% followed by HNO3 30%, sand blasted, and acid etched using either 50 μm Al2O3 (SLA50) or 250 μm Al2 O3 grit (SLA250). Characterization of the surfaces included energy dispersive X-ray analysis (EDX), contact angle, and surface roughness analysis. Human MSCs were cultured onto the four CoCrMo substrates and markers of cell attachment, retention, proliferation, cytotoxicity, and osteogenic differentiation were studied. Residual aluminum was observed on both SLA surfaces although this appeared to be more widely spread on SLA50, whilst SLA250 was shown to have the roughest topography with an Ra value greater than 1 μm. All substrates were shown to be largely non-cytotoxic although both SLA surfaces were shown to reduce cell attachment, whilst SLA50 also delayed cell proliferation. In contrast, SLA250 stimulated a good rate of proliferation resulting in the largest cell population by day 21. In addition, SLA250 stimulated enhanced cell retention, calcium deposition, and hydroxyapatite formation compared to SMO (p < 0.05). The enhanced response stimulated by SLA250 surface modification may prove advantageous for increasing the bioactivity of implants formed of CoCrMo. PMID:26015290

  9. Mesenchymal stem cell response to topographically modified CoCrMo

    PubMed Central

    Logan, Niall; Bozec, Laurent; Traynor, Alison

    2015-01-01

    Abstract Surface roughness on implant materials has been shown to be highly influential on the behavior of osteogenic cells. Four surface topographies were engineered on cobalt chromium molybdenum (CoCrMo) in order to examine this influence on human mesenchymal stem cells (MSC). These treatments were smooth polished (SMO), acid etched (AE) using HCl 7.4% and H2SO4 76% followed by HNO3 30%, sand blasted, and acid etched using either 50 μm Al2O3 (SLA50) or 250 μm Al2O3 grit (SLA250). Characterization of the surfaces included energy dispersive X‐ray analysis (EDX), contact angle, and surface roughness analysis. Human MSCs were cultured onto the four CoCrMo substrates and markers of cell attachment, retention, proliferation, cytotoxicity, and osteogenic differentiation were studied. Residual aluminum was observed on both SLA surfaces although this appeared to be more widely spread on SLA50, whilst SLA250 was shown to have the roughest topography with an R a value greater than 1 μm. All substrates were shown to be largely non‐cytotoxic although both SLA surfaces were shown to reduce cell attachment, whilst SLA50 also delayed cell proliferation. In contrast, SLA250 stimulated a good rate of proliferation resulting in the largest cell population by day 21. In addition, SLA250 stimulated enhanced cell retention, calcium deposition, and hydroxyapatite formation compared to SMO (p < 0.05). The enhanced response stimulated by SLA250 surface modification may prove advantageous for increasing the bioactivity of implants formed of CoCrMo. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 3747–3756, 2015. PMID:26015290

  10. Corrosion and degradation of a polyurethane/Co-Ni-Cr-Mo pacemaker lead

    SciTech Connect

    Sung, P.; Fraker, A.C.

    1987-12-01

    An investigation to study changes in the metal surfaces and the polyurethane insulation of heart pacemaker leads under controlled in vitro conditions was conducted. A polyurethane (Pellethane 2363-80A)/Co-Ni-Cr-Mo (MP35N) wire lead was exposed in Hanks' physiological saline solution for 14 months and then analyzed using scanning electron microscopy, x-ray energy dispersive analysis, and small angle x-ray scattering. Results showed that some leakage of solution into the lead had occurred and changes were present on both the metal and the polyurethane surfaces.

  11. Experimental procedure for crevice corrosion studies of Ni-Cr-Mo alloys in natural seawater

    NASA Astrophysics Data System (ADS)

    Martin, F. J.; Lucas, K. E.; Hogan, E. A.

    2002-03-01

    An experimental procedure intended for crevice corrosion studies on Ni-Cr-Mo alloys is demonstrated. In this procedure a potentiostatic control of crevice corrosion specimens is applied to an immersible crevice cell design that uses a fluoroelastomer gasket crevice former. The procedure is demonstrated for a crevice susceptibility study on Alloy 625 in elevated temperature natural seawater, where crevice corrosion initiation and propagation are shown to be influenced by the electrochemical potential. Potentiostatic current monitoring establishes the crevice initiation time and rate of propagation, while post-mortem inspections confirm the extent of crevice damage.

  12. Nano-cluster stability following neutron irradiation in MA957 oxide dispersion strengthened material

    NASA Astrophysics Data System (ADS)

    Ribis, J.; Lozano-Perez, S.

    2014-01-01

    ODS steels are promising materials for Sodium cooled Fast Reactors since their fine distribution of nano-clusters confers excellent mechanical properties. However, the nano-feature stability needs to be assessed under neutron irradiation. Before irradiation, the characterizations show that nano-particles are finely distributed within the ferritic matrix and are identified to have a pyrochlore type structure. After irradiation of the MA957 alloy in the Phenix French reactor at 412 °C up to 50 dpa and 430 °C up to 75 dpa, transmission electron microscopy characterization reveals a very slight density fall but no distinguishable difference in nano-features size before and after irradiation. In addition, after both irradiations, the nano-oxides are still (Y, Ti, O) compounds with orientation relationship with the matrix. A multislice simulation of high resolution images suggests that nano-particles still have a fcc pyrochlore type structure after irradiation. A possible change of lattice parameter seems to be highlighted, possibly due to disordering by cascade effect.

  13. Defect-induced magnetism in graphite through neutron irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Yutian; Pochet, Pascal; Jenkins, Catherine A.; Arenholz, Elke; Bukalis, Gregor; Gemming, Sibylle; Helm, Manfred; Zhou, Shengqiang

    2014-12-01

    We have investigated the variation in the magnetization of highly ordered pyrolytic graphite (HOPG) after neutron irradiation, which introduces defects in the bulk sample and consequently gives rise to a large magnetic signal. We observe strong paramagnetism in HOPG, increasing with the neutron fluence. The induced paramagnetism can be well correlated with structural defects by comparison with density-functional theory calculations. In addition to the in-plane vacancies, the transplanar defects also contribute to the magnetization. The lack of any magnetic order between the local moments is possibly due to the absence of hydrogen/nitrogen chemisorption, or the magnetic order cannot be established at all in the bulk form.

  14. Localized Corrosion of a Neutron Absorbing Ni-Cr-Mo-Gd Alloy

    SciTech Connect

    R.E. Mizia; T. E. Lister; P. J. Pinhero; T. L. Trowbridge

    2005-04-01

    The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), has developed a new nickel-chromium-molybdenum-gadolinium structural alloy for storage and long-term disposal of spent nuclear fuel (SNF). The new alloy will be used for SNF storage container inserts for nuclear criticality control. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section. This alloy must be resistant to localized corrosion when exposed to postulated Yucca Mountain in-package chemistries. The corrosion resistance properties of three experimental heats of this alloy are presented. The alloys performance are be compared to Alloy 22 and borated stainless steel. The results show that initially the new Ni-Cr-Mo-Gd alloy is less resistant to corrosion as compared to another Ni-Cr-Mo-Gd alloy (Alloy 22); but when the secondary phase that contains gadolinium (gadolinide) is dissolved, the alloy surface becomes passive. The focus of this work is to qualify these gadolinium containing materials for ASME code qualification and acceptance in the Yucca Mountain Repository.

  15. Reduction of Cr, Mo, Se and U by Desulfovibrio desulfuricans immobilized in polyacrylamide gels.

    PubMed

    Tucker, M D; Barton, L L; Thomson, B M

    1998-01-01

    Intact cells of Desulfovibrio desulfuricans, immobilized in polyacrylamide gel, removed Cr, Mo, Se and U from solution by enzymatic-mediated reduction reactions. Lactate or H2 served as the electron donor and the oxidized Cr(VI), Mo(VI), Se(VI) and U(VI) served as electron acceptors. Reduction of the oxidized metal species resulted in the precipitation of solid phases of the metals. Metal removal efficiencies of 86-96% were achieved for initial concentrations of 1 mM Mo, Se, and U and 0.5 mM Cr. Insoluble metal phases accumulated on both the surface and the interior of the polyacrylamide gel. In column tests conducted for U removal, effluent concentrations less than 20 micrograms L(-1) were achieved with initial concentrations of 5 mg L(-1) and 20 mg L(-1) U and residence times from 25-37 h. The enzymatic reduction of Cr, Mo, Se, and U by immobilized cells of D. desulfuricans may be a practical method for removing these metals from solution in a biological reactor. PMID:9565467

  16. Removal of B, Cr, Mo, and Se from wastewater by incorporation into hydrocalumite and ettringite.

    PubMed

    Zhang, Min; Reardon, Eric J

    2003-07-01

    Boron, chromium, molybdenum, and selenium often occur in high concentrations in fly ash leachates. During the leaching of fly ash in alkaline environments, hydrocalumite (Ca4Al2(OH)12(OH)2 x 6H2O) and ettringite (Ca6Al2(OH)12(SO4)3 x 26H20) form as secondary precipitates. In this study, the removal of B, Cr, Mo, and Se oxyanions from high pH waters by incorporation into hydrocalumite and ettringite was examined. Experiments were performed by precipitating these minerals in solutions containing B, Cr, Mo, and Se oxyanions at conditions relevant to lime-leaching of fly ash as well as to fly ash containing concrete. The uptake of all four anions by hydrocalumite and ettringite was high. Anion uptake by hydrocalumite was larger than that by ettringite, and hydrocalumite was able to reduce anion concentrations to below drinking water standards. Ettringite showed an anion preference in the order of B(OH)4- > SeO4(2-) > CrO4(2-) > MoO4(2-). In contrast, borate was least preferred by hydrocalumite. Coordination, size, and electronegativity are likely the factors that result in the observed differences among the oxyanions.

  17. Investigation on Mechanical Properties of 9%Cr/CrMoV Dissimilar Steels Welded Joint

    NASA Astrophysics Data System (ADS)

    Liu, Xia; Lu, Fenggui; Yang, Renjie; Wang, Peng; Xu, Xiaojin; Huo, Xin

    2015-04-01

    Advanced 9%Cr steel with good heat resistance and CrMoV with good toughness were chosen as candidate materials to fabricate combined rotor for steam turbine operating at over 620 °C. But the great difference in base metals properties presents a challenge in achieving sound defect-free joint with optimal properties in dissimilar welded rotor. In this paper, appropriate selection of filler metal, welding parameters, and post-weld heat treatment was combined to successfully weld 1100-mm-diameter 9%Cr/CrMoV dissimilar experimental rotor through ultra-narrow gap submerge arc welding. Some properties such as hardness, low-cycle fatigue (LCF), and high-cycle fatigue (HCF) combined with microstructural characterization qualify the integrity of the weld. Microstructural analysis indicated the presence of high-temperature tempered martensite as the phase responsible for the improved properties obtained in the weld. The Coffin-Manson parameters were obtained by fitting the data in LCF test, while the conditional fatigue strength was derived from the HCF test based on S-N curve. Analysis of hardness profile showed that the lowest value occurred at heat-affected zone adjacent to base metal which represents the appropriate location of fracture for the samples after LCF and HCF tests.

  18. Biomaterial Co-Cr-Mo Alloys Nano Coating Calcium Phosphate Orthopedic Treatment

    NASA Astrophysics Data System (ADS)

    Palaniappan, N.; Inwati, Gajendra Kumar; Singh, Man

    2014-08-01

    The modem study a thermal martensitic transformation of biomedical Co-Cr-Mo alloys and ultimately offers large elongation to failure while maintaining high strength. In the future study, structural evolution and dislocation slip as an elementary process in the martensitic transformation in Co-Cr-Mo alloys were investigated to reveal the origin of their enhanced phase stability due to nitrogen addition and coating of calcium phosphate specimens with and without nitrogen addition were prepared. The N-doped alloys had a single-phase matrix, whereas the N-free alloys had a duplex microstructure. Irrespective of the nitrogen content, dislocations frequently dissociated into Shockley partial dislocations with stacking faults. The Nano range coating of calcium phosphate function as obstacles to the glide of partial dislocations and consequently significantly affect the kinetics of the martensitic transformation. As a result, the formation of marten site plays a crucial role in plastic deformation and wear behavior, the developed nanostructures modification associated with nitrogen addition must be a promising strategy for highly durable orthopedic implants.

  19. Nanostructure characterisation of flow-formed Cr-Mo-V steel using transmission Kikuchi diffraction technique.

    PubMed

    Birosca, S; Ding, R; Ooi, S; Buckingham, R; Coleman, C; Dicks, K

    2015-06-01

    Nowadays flow-forming has become a desired near net shape manufacturing method as it provides excellent mechanical properties with improved surface finish and significant manufacturing cost reduction. However, the material is subjected to excessive plastic deformation during flow-forming process, generating a very fine and complex microstructure. In addition, the intense dislocation density and residual stress that is generated in the component during processing makes the microstructure characterisation using conventional micro-analytical tools challenging. Thus, the microstructure/property relationship study in such a material is rather difficult. In the present study a flow-formed Cr-Mo-V steel nanostructure and crystallographic texture were characterised by means of Transmission Kikuchi Diffraction (TKD). Here, TKD is shown to be a powerful technique in revealing very fine martensite laths within an austenite matrix. Moreover, fine precipitates in the order of 20-70 nm on the martensite lath boundaries were clearly imaged and characterised. This greatly assisted in understanding the preferable site formation of the carbides in such a complex microstructure. The results showed that the actual TKD spatial resolution was in the range of 5-10 nm using 25 kV for flow-formed Cr-Mo-V steel.

  20. Defect microstructures in neutron-irradiated copper and stainless steel

    SciTech Connect

    Zinkle, S.J.; Sindelar, R.L.

    1987-09-01

    The defect microstructures of copper and type 304L austenitic stainless steel have been examined following neutron irradiation under widely different conditions. Less than 0.2% of the defect clusters in steel irradiated at 120/sup 0/C with moderated fission neutrons were resolvable as stacking fault tetrahedra (SFT). The fraction of defect clusters identified as SFT in copper varied from approx.10% for a low-dose 14-MeV neutron irradiation at 25/sup 0/C to approx.50% for copper irradiated to 1.3 dpa in a moderated fission spectrum at 182/sup 0/C. The mean cluster size in copper was about 2.6 nm for both cases, despite the large differences in irradiation conditions. The mean defect cluster size in the irradiated steel was about 1.8 nm. The absence of SFT in stainless steel may be due to the generation of 35 appm He during the irradiation, which caused the vacancies to form helium-filled cavities instead of SFT. 20 refs.

  1. Impurities effect on the swelling of neutron irradiated beryllium

    SciTech Connect

    Donne, M.D.; Scaffidi-Argentina, F.

    1995-09-01

    An important factor controlling the swelling behaviour of fast neutron irradiated beryllium is the impurity content which can strongly affect both the surface tension and the creep strength of this material. Being the volume swelling of the old beryllium (early sixties) systematically higher than that of the more modem one (end of the seventies), a sensitivity analysis with the aid of the computer code ANFIBE (ANalysis of Fusion Irradiated BEryllium) to investigate the effect of these material properties on the swelling behaviour of neutron irradiated beryllium has been performed. Two sets of experimental data have been selected: the first one named Western refers to quite recently produced Western beryllium, whilst the second one, named Russian refers to relatively old (early sixties) Russian beryllium containing a higher impurity rate than the Western one. The results obtained with the ANFIBE Code were assessed by comparison with experimental data and the used material properties were compared with the data available in the literature. Good agreement between calculated and measured values has been found.

  2. Effect of bimodal harmonic structure design on the deformation behaviour and mechanical properties of Co-Cr-Mo alloy.

    PubMed

    Vajpai, Sanjay Kumar; Sawangrat, Choncharoen; Yamaguchi, Osamu; Ciuca, Octav Paul; Ameyama, Kei

    2016-01-01

    In the present work, Co-Cr-Mo alloy compacts with a unique bimodal microstructural design, harmonic structure design, were successfully prepared via a powder metallurgy route consisting of controlled mechanical milling of pre-alloyed powders followed by spark plasma sintering. The harmonic structured Co-Cr-Mo alloy with bimodal grain size distribution exhibited relatively higher strength together with higher ductility as compared to the coarse-grained specimens. The harmonic Co-Cr-Mo alloy exhibited a very complex deformation behavior wherein it was found that the higher strength and the high retained ductility are derived from fine-grained shell and coarse-grained core regions, respectively. Finally, it was observed that the peculiar spatial/topological arrangement of stronger fine-grained and ductile coarse-grained regions in the harmonic structure promotes uniformity of strain distribution, leading to improved mechanical properties by suppressing the localized plastic deformation during straining. PMID:26478398

  3. Optical absorption and luminescence in neutron-irradiated, silica-based fibers

    SciTech Connect

    Cooke, D.W.; Farnum, E.H.; Clinard, F.W.

    1995-04-01

    The objectives of this work are to assess the effects of thermal annealing and photobleaching on the optical absorption of neutron-irradiated, silica fibers of the type proposed for use in ITER diagnostics, and to measure x-ray induced luminescence of unirradiated (virgin) and neutron-irradiated fibers.

  4. Irradiation response of delta ferrite in as-cast and thermally aged cast stainless steel

    SciTech Connect

    Li, Zhangbo; Lo, Wei-Yang; Chen, Yiren; Pakarinen, Janne; Wu, Yaqiao; Allen, Todd; Yang, Yong

    2015-08-08

    To enable the life extension of Light Water Reactors (LWRs) beyond 60 years, it is critical to gain adequate knowledge for making conclusive predictions to assure the integrity of duplex stainless steel reactor components, e.g. primary pressure boundary and reactor vessel internal. Microstructural changes in the ferrite of thermally aged, neutron irradiated only, and neutron irradiated after being thermally aged cast austenitic stainless steels (CASS) were investigated using atom probe tomography. The thermal aging was performed at 400 °C for 10,000 h and the irradiation was conducted in the Halden reactor at ~315 °C to 0.08 dpa (5.6 × 1019 n/cm2 E > 1 MeV). Low dose neutron irradiation at a dose rate of 5 × 10-9 dpa/s was found to induce spinod,al decomposition in the ferrite of as-cast microstructure, and further to enhance the spinodal decomposition in the thermally aged cast alloys. Regarding the G-phase precipitates, the neutron irradiation dramatically increases the precipitate size, and alters the composition of the precipitates with increased, Mn, Ni, Si and Mo and reduced Fe and Cr contents. Lastly, The results have shown that low dose neutron irradiation can further accelerate the degradation of ferrite in a duplex stainless steel at the LWR relevant condition.

  5. Irradiation response of delta ferrite in as-cast and thermally aged cast stainless steel

    DOE PAGESBeta

    Li, Zhangbo; Lo, Wei-Yang; Chen, Yiren; Pakarinen, Janne; Wu, Yaqiao; Allen, Todd; Yang, Yong

    2015-08-08

    To enable the life extension of Light Water Reactors (LWRs) beyond 60 years, it is critical to gain adequate knowledge for making conclusive predictions to assure the integrity of duplex stainless steel reactor components, e.g. primary pressure boundary and reactor vessel internal. Microstructural changes in the ferrite of thermally aged, neutron irradiated only, and neutron irradiated after being thermally aged cast austenitic stainless steels (CASS) were investigated using atom probe tomography. The thermal aging was performed at 400 °C for 10,000 h and the irradiation was conducted in the Halden reactor at ~315 °C to 0.08 dpa (5.6 × 1019more » n/cm2 E > 1 MeV). Low dose neutron irradiation at a dose rate of 5 × 10-9 dpa/s was found to induce spinod,al decomposition in the ferrite of as-cast microstructure, and further to enhance the spinodal decomposition in the thermally aged cast alloys. Regarding the G-phase precipitates, the neutron irradiation dramatically increases the precipitate size, and alters the composition of the precipitates with increased, Mn, Ni, Si and Mo and reduced Fe and Cr contents. Lastly, The results have shown that low dose neutron irradiation can further accelerate the degradation of ferrite in a duplex stainless steel at the LWR relevant condition.« less

  6. Ratcheting induced cyclic softening behaviour of 42CrMo4 steel

    NASA Astrophysics Data System (ADS)

    Kreethi, R.; Mondal, A. K.; Dutta, K.

    2015-02-01

    Ratcheting is an important field of fatigue deformation which happens under stress controlled cyclic loading of materials. The aim of this investigation is to study the uniaxial ratcheting behavior of 42CrMo4 steel in annealed condition, under various applied stresses. In view of this, stress controlled fatigue tests were carried out at room temperature up to 200 cycles using a servo-hydraulic universal testing machine. The results indicate that accumulation of ratcheting strain increases monotonically with increasing maximum applied stress however; the rate of strain accumulation attains a saturation plateau after few cycles. The investigated steel shows cyclic softening behaviour under the applied stress conditions. The nature of strain accumulation and cyclic softening has been discussed in terms of dislocation distribution and plastic damage incurred in the material.

  7. Characterization of Wear Particles Generated from CoCrMo Alloy under Sliding Wear Conditions

    PubMed Central

    Pourzal, R.; Catelas, I.; Theissmann, R.; Kaddick, C.; Fischer, A.

    2011-01-01

    Biological effects of wear products (particles and metal ions) generated by metal-on-metal (MoM) hip replacements made of CoCrMo alloy remain a major cause of concern. Periprosthetic osteolysis, potential hypersensitivity response and pseudotumour formation are possible reactions that can lead to early revisions. To accurately analyse the biological response to wear particles from MoM implants, the exact nature of these particles needs to be characterized. Most previous studies used energy-dispersive X-ray spectroscopy (EDS) analysis for characterization. The present study used energy filtered transmission electron microscopy (TEM) and electron diffraction pattern analysis to allow for a more precise determination of the chemical composition and to gain knowledge of the crystalline structure of the wear particles. Particles were retrieved from two different test rigs: a reciprocating sliding wear tribometer (CoCrMo cylinder vs. bar) and a hip simulator according to ISO 14242-1 (CoCrMo head vs. CoCrMo cup). All tests were conducted in bovine serum. Particles were retrieved from the test medium using a previously published enzymatic digestion protocol. Particles isolated from tribometer samples had a size of 100 – 500 nm. Diffraction pattern analysis clearly revealed the lattice structure of strain induced hcp ε-martensite. Hip simulator samples revealed numerous particles of 15 – 30 nm and 30 – 80 nm size. Most of the larger particles appeared to be only partially oxidized and exhibited cobalt locally. The smallest particles were Cr2O3 with no trace of cobalt. It optically appeared that these Cr2O3 particles were flaking off the surface of larger particles that depicted a very high intensity of oxygen, as well as chromium, and only background noise of cobalt. The particle size difference between the two test rigs is likely related to the conditions of the two tribosystems, in particular the difference in the sample geometry and in the type of sliding

  8. Carbides in iron-rich Fe-Mn-Cr-Mo-Al-Si-C systems

    NASA Technical Reports Server (NTRS)

    Lemkey, F. D.; Gupta, H.; Nowotny, H.; Wayne, S. F.

    1984-01-01

    The optimization of high carbon iron-base superalloy properties with duplex microstructure gamma + M7C3 carbide requires analysis in the context of a seven-component system. Data are first provided here for the Fe-Mn-Cr-Mo-C quinary system, at 30 at. pct carbon. A characterization of competing carbides, according to a pseudoternary phase diagram at 35 wt pct iron, is made from isothermal sections. It is noted that while M7C3 and M3C carbides' occurrences are respectively favored at the Cr and Mn corners, the M2C carbide and molybdenum cementite are predominant with increasing amounts of Mo. Lattice parameters are reported for the various carbides.

  9. Entropy and Diffuse Scattering: Comparison of NbTiVZr and CrMoNbV

    NASA Astrophysics Data System (ADS)

    Widom, Michael

    2016-07-01

    The chemical disorder intrinsic to high-entropy alloys inevitably creates diffuse scattering in their X-ray or neutron diffraction patterns. Through first principles hybrid Monte Carlo/molecular dynamics simulations of two BCC high-entropy alloy forming compounds, CrMoNbV and NbTiVZr, we identify the contributions of chemical disorder, atomic size, and thermal fluctuations to the diffuse scattering. As a side benefit, we evaluate the reduction in entropy due to pair correlations within the framework of the cluster variation method. Finally, we note that the preference of Ti and Zr for hexagonal structures at low temperature leads to a mechanical instability reducing the local BCC character of NbTiVZr, while preserving global BCC symmetry.

  10. Technology and experiments of 42CrMo bearing ring forming based on casting ring blank

    NASA Astrophysics Data System (ADS)

    Li, Yongtang; Ju, Li; Qi, Huiping; Zhang, Feng; Chen, Guozhen; Wang, Mingli

    2014-03-01

    Bearing ring is the crucial component of bearing. With regard to such problems as material waste, low efficiency and high energy consumption in current process of producing large bearing ring, a new process named "casting-rolling compound forming technology" is researched by taking the typical 42CrMo slew bearing as object. Through theoretical analysis, the design criteria of the main casting-rolling forming parameters are put forward at first. Then the constitutive relationship model of as-cast 42CrMo steel and its mathematical model of dynamic recrystallization are obtained according to the results of the hot compression experiment. By a coupled thermal-mechanical finite element model for radial-axial rolling of bearing ring, the fraction of dynamic recrystallization is calculated and recrystallized grains size are predicated. Meanwhile, the effects of the initial rolling temperature and feed rate of idle roll on material microstructure evolution are analyzed. Finally, the industrial rolling experiment is designed and performed, based on the simulation results. In addition, mechanical and metallographic tests are conducted on rolled bearing ring to get the mechanical parameters and metallographic structure. The experimental data and results show that the mechanical properties of bearing ring produced by casting-rolling compound forming technology are up to industrial standard, and a qualified bearing ring can be successfully formed by employing this new technology. Through the study, a process of forming large bearing ring directly by using casting ring blank is obtained, which could provide an effective theoretical guidance for manufacturing large ring parts. It also has an edge in saving material, lowering energy and improving efficiency.

  11. Fatigue strength of Co-Cr-Mo alloy clasps prepared by selective laser melting.

    PubMed

    Kajima, Yuka; Takaichi, Atsushi; Nakamoto, Takayuki; Kimura, Takahiro; Yogo, Yoshiaki; Ashida, Maki; Doi, Hisashi; Nomura, Naoyuki; Takahashi, Hidekazu; Hanawa, Takao; Wakabayashi, Noriyuki

    2016-06-01

    We aimed to investigate the fatigue strength of Co-Cr-Mo clasps for removable partial dentures prepared by selective laser melting (SLM). The Co-Cr-Mo alloy specimens for tensile tests (dumbbell specimens) and fatigue tests (clasp specimens) were prepared by SLM with varying angles between the building and longitudinal directions (i.e., 0° (TL0, FL0), 45° (TL45, FL45), and 90° (TL90, FL90)). The clasp specimens were subjected to cyclic deformations of 0.25mm and 0.50mm for 10(6) cycles. The SLM specimens showed no obvious mechanical anisotropy in tensile tests and exhibited significantly higher yield strength and ultimate tensile strength than the cast specimens under all conditions. In contrast, a high degree of anisotropy in fatigue performance associated with the build orientation was found. For specimens under the 0.50mm deflection, FL90 exhibited significantly longer fatigue life (205,418 cycles) than the cast specimens (112,770 cycles). In contrast, the fatigue lives of FL0 (28,484 cycles) and FL45 (43,465 cycles) were significantly shorter. The surface roughnesses of FL0 and FL45 were considerably higher than those of the cast specimens, whereas there were no significant differences between FL90 and the cast specimens. Electron backscatter diffraction (EBSD) analysis indicated the grains of FL0 showed preferential close to <001> orientation of the γ phase along the normal direction to the fracture surface. In contrast, the FL45 and FL90 grains showed no significant preferential orientation. Fatigue strength may therefore be affected by a number of factors, including surface roughness and crystal orientation. The SLM process is a promising candidate for preparing tough removable partial denture frameworks, as long as the appropriate build direction is adopted.

  12. Texture evolution and mechanical anisotropy of biomedical hot-rolled Co-Cr-Mo alloy.

    PubMed

    Mori, Manami; Yamanaka, Kenta; Sato, Shigeo; Chiba, Akihiko

    2015-11-01

    Crystallographic textures and their effect on the mechanical anisotropy of a hot-rolled biomedical Co-Cr-Mo alloy were investigated. The hot-rolled Co-28Cr-6Mo-0.13N (mass%) alloy examined here exhibited a monotonic strength increment following hot-rolling reduction, eventually reaching a 0.2% proof stress of 1400 MPa while maintaining acceptable ductility (>10%). The dominant hot-rolling texture was a brass-type component, which is characterized by the alloy's peculiarly low stacking fault energy (SFE) even at hot rolling temperatures, although the minor peaks of the near copper component were also identified. However, because of the onset of dynamic recrystallization (DRX) during the hot rolling process, the texture intensity was relatively weak even after 90% hot rolling, although the grain refinement originating from the DRX was not significant (the "less active DRX" condition increased the strain accumulation during the process, resulting in high-strength samples). The weakened texture development resulted in negligible in-plane anisotropy for the hot-rolled specimen strength, when the specimens were tensile strained in the rolling direction (RD) and transverse direction (TD). The elongation-to-failure, however, exhibited a difference with respect to the tensile loading axis. It is suggested that the ductility anisotropy is closely related to a strain-induced γ (fcc) → ε (hcp) martensitic transformation during tensile loading, resulting in a difference in the proportion of quasi-cleavage fracture surfaces. The obtained results will be helpful in the development of high-strength Co-Cr-Mo alloy plates and sheets, and have implications regarding plastic deformation and texture evolution during the hot rolling of non-conventional metallic materials with low SFE at elevated temperatures, where planar dislocation slips of Shockley partial dislocations and thermally activated process interplay.

  13. Morphology of Co-Cr-Mo dental alloy surfaces polished by three different mechanical procedures.

    PubMed

    Ţălu, Ştefan; Stach, Sebastian; Klaić, Boris; Mišić, Tea; Malina, Jadranka; Čelebić, Asja

    2015-09-01

    The present study aims at characterizing the three-dimensional (3-D) morphology of a Co-Cr-Mo dental alloy surface as a result of three different procedures used for polishing it. The sample surface morphology of the sampled surface was examined employing atomic force microscopy (AFM), statistical surface roughness parameters, and fractal analysis. An extra-hard dental alloy of cobalt-chromium-molybdenum (Co-Cr-Mo) (Wironit(®) , from BEGO, Bremen, Germany) was prepared and moulded. Different polishing treatments were carried out on three groups of six samples each--a total of 18 samples. The first group contained six electropolished (EP) samples. The second group containing six samples went through a mechanical polishing process employing green rubber discs and a high shine polishing paste applied by a rotating black brush (BB). The third group comprising six samples as well went through a mechanical polishing process by means of green rubber discs, high shine polishing paste, and a rotating deer leather brush (DL). Fractal analysis on the basis of a computational algorithm applied to the AFM data was employed for the 3-D quantitative characterization of the morphology of the sampled surfaces. The fractal dimension D (average ± standard deviation) of 3-D surfaces for BB samples (2.19 ± 0.07) is lower than that of the DL samples (2.24 ± 0.08), which is still lower than that of the EP samples (2.27 ± 0.09). The results indicated the BB samples as presenting the lowest values of statistical surface roughness parameters, thus the best surface finish, while the EP samples yielded the highest values. PMID:26190754

  14. Fatigue strength of Co-Cr-Mo alloy clasps prepared by selective laser melting.

    PubMed

    Kajima, Yuka; Takaichi, Atsushi; Nakamoto, Takayuki; Kimura, Takahiro; Yogo, Yoshiaki; Ashida, Maki; Doi, Hisashi; Nomura, Naoyuki; Takahashi, Hidekazu; Hanawa, Takao; Wakabayashi, Noriyuki

    2016-06-01

    We aimed to investigate the fatigue strength of Co-Cr-Mo clasps for removable partial dentures prepared by selective laser melting (SLM). The Co-Cr-Mo alloy specimens for tensile tests (dumbbell specimens) and fatigue tests (clasp specimens) were prepared by SLM with varying angles between the building and longitudinal directions (i.e., 0° (TL0, FL0), 45° (TL45, FL45), and 90° (TL90, FL90)). The clasp specimens were subjected to cyclic deformations of 0.25mm and 0.50mm for 10(6) cycles. The SLM specimens showed no obvious mechanical anisotropy in tensile tests and exhibited significantly higher yield strength and ultimate tensile strength than the cast specimens under all conditions. In contrast, a high degree of anisotropy in fatigue performance associated with the build orientation was found. For specimens under the 0.50mm deflection, FL90 exhibited significantly longer fatigue life (205,418 cycles) than the cast specimens (112,770 cycles). In contrast, the fatigue lives of FL0 (28,484 cycles) and FL45 (43,465 cycles) were significantly shorter. The surface roughnesses of FL0 and FL45 were considerably higher than those of the cast specimens, whereas there were no significant differences between FL90 and the cast specimens. Electron backscatter diffraction (EBSD) analysis indicated the grains of FL0 showed preferential close to <001> orientation of the γ phase along the normal direction to the fracture surface. In contrast, the FL45 and FL90 grains showed no significant preferential orientation. Fatigue strength may therefore be affected by a number of factors, including surface roughness and crystal orientation. The SLM process is a promising candidate for preparing tough removable partial denture frameworks, as long as the appropriate build direction is adopted. PMID:26974490

  15. Plastic Deformation Behavior and Processing Maps of 35CrMo Steel

    NASA Astrophysics Data System (ADS)

    Xiao, Zheng-bing; Huang, Yuan-chun; Liu, Yu

    2016-03-01

    Hot deformation behavior of 35CrMo steel was investigated by compression tests in the temperature range of 850 to 1150 °C and strain rate range of 0.01 to 20 s-1 on a Gleeble-3810 thermal simulator. According to processing maps constructed based on the experimental data and using the principle of dynamic materials modeling (DMM), when the strain is 0.8, three safe regions with comparatively high efficiency of power dissipation were identified: (850 to 920) °C/(0.01 to 0.02) s-1, (850 to 900) °C/(10 to 20) s-1, and (1050 to 1150) °C/(0.01 to 1) s-1. And the domain of (920 to 1150) °C/(2.7 to 20) s-1 is within the instability range, whose efficiency of power dissipation is around 0.05. The deformed optical microstructure indicated that the combination of low deformation temperature (850 °C) and a relatively high strain rate (20 s-1) resulted in the smallest dynamic recrystallized grains, but coarser grains were obtained when a much higher strain rate was employed (50 s-1). A lower strain rate or a higher temperature will accelerate the growth of grains, and both high temperature and high strain rate can cause microcracks in the deformed steel. Integration of the processing map into the optical microstructure identified the region of (850 to 900) °C/(10 to 20) s-1 as the ideal condition for the hot deformation of 35CrMo steel.

  16. Microstructural characterization of as-cast biocompatible Co-Cr-Mo alloys

    SciTech Connect

    Giacchi, J.V.; Morando, C.N.; Fornaro, O.; Palacio, H.A.

    2011-01-15

    The microstructure of a cobalt-base alloy (Co-Cr-Mo) obtained by the investment casting process was studied. This alloy complies with the ASTM F75 standard and is widely used in the manufacturing of orthopedic implants because of its high strength, good corrosion resistance and excellent biocompatibility properties. This work focuses on the resulting microstructures arising from samples poured under industrial environment conditions, of three different Co-Cr-Mo alloys. For this purpose, we used: 1) an alloy built up from commercial purity constituents, 2) a remelted alloy and 3) a certified alloy for comparison. The characterization of the samples was achieved by using optical microscopy (OM) with a colorant etchant to identify the present phases and scanning electron microscopy (SE-SEM) and energy dispersion spectrometry (EDS) techniques for a better identification. In general the as-cast microstructure is a Co-fcc dendritic matrix with the presence of a secondary phase, such as the M{sub 23}C{sub 6} carbides precipitated at grain boundaries and interdendritic zones. These precipitates are the main strengthening mechanism in this type of alloys. Other minority phases were also reported and their presence could be linked to the cooling rate and the manufacturing process variables and environment. - Research Highlights: {yields}The solidification microstructure of an ASTM-F75 type alloy were studied. {yields}The alloys were poured under an industrial environment. {yields}Carbides and sigma phase identified by color metallography and scanning microscopy (SEM and EDS). {yields}Two carbide morphologies were detected 'blocky type' and 'pearlite type'. {yields}Minority phases were also detected.

  17. New Insights into Hard Phases of CoCrMo Metal-on-Metal Hip Replacements

    PubMed Central

    Liao, Y.; Pourzal, R.; Stemmer, P.; Wimmer, M.A.; Jacobs, J.J.; Fischer, A.; Marks, L. D.

    2012-01-01

    The microstructural and mechanical properties of the hard phases in CoCrMo prosthetic alloys in both cast and wrought conditions were examined using transmission electron microscopy and nanoindentation. Besides the known carbides of M23C6-type (M=Cr, Mo, Co) and M6C-type which are formed by either eutectic solidification or precipitation, a new mixed-phase hard constituent has been found in the cast alloys, which is composed of ~100 nm fine grains. The nanosized grains were identified to be mostly of M23C6 type using nano-beam precession electron diffraction, and the chemical composition varied from grain to grain being either Cr- or Co-rich. In contrast, the carbides within the wrought alloy having the same M23C6 structure were homogeneous, which can be attributed to the repeated heating and deformation steps. Nanoindentation measurements showed that the hardness of the hard phase mixture in the cast specimen was ~15.7 GPa, while the M23C6 carbides in the wrought alloy were twice as hard (~30.7 GPa). The origin of the nanostructured hard phase mixture was found to be related to slow cooling during casting. Mixed hard phases were produced at a cooling rate of 0.2 °C/s, whereas single phase carbides were formed at a cooling rate of 50 °C/s. This is consistent with sluggish kinetics and rationalizes different and partly conflicting microstructural results in the literature, and could be a source of variations in the performance of prosthetic devices in-vivo. PMID:22659365

  18. Texture evolution and mechanical anisotropy of biomedical hot-rolled Co-Cr-Mo alloy.

    PubMed

    Mori, Manami; Yamanaka, Kenta; Sato, Shigeo; Chiba, Akihiko

    2015-11-01

    Crystallographic textures and their effect on the mechanical anisotropy of a hot-rolled biomedical Co-Cr-Mo alloy were investigated. The hot-rolled Co-28Cr-6Mo-0.13N (mass%) alloy examined here exhibited a monotonic strength increment following hot-rolling reduction, eventually reaching a 0.2% proof stress of 1400 MPa while maintaining acceptable ductility (>10%). The dominant hot-rolling texture was a brass-type component, which is characterized by the alloy's peculiarly low stacking fault energy (SFE) even at hot rolling temperatures, although the minor peaks of the near copper component were also identified. However, because of the onset of dynamic recrystallization (DRX) during the hot rolling process, the texture intensity was relatively weak even after 90% hot rolling, although the grain refinement originating from the DRX was not significant (the "less active DRX" condition increased the strain accumulation during the process, resulting in high-strength samples). The weakened texture development resulted in negligible in-plane anisotropy for the hot-rolled specimen strength, when the specimens were tensile strained in the rolling direction (RD) and transverse direction (TD). The elongation-to-failure, however, exhibited a difference with respect to the tensile loading axis. It is suggested that the ductility anisotropy is closely related to a strain-induced γ (fcc) → ε (hcp) martensitic transformation during tensile loading, resulting in a difference in the proportion of quasi-cleavage fracture surfaces. The obtained results will be helpful in the development of high-strength Co-Cr-Mo alloy plates and sheets, and have implications regarding plastic deformation and texture evolution during the hot rolling of non-conventional metallic materials with low SFE at elevated temperatures, where planar dislocation slips of Shockley partial dislocations and thermally activated process interplay. PMID:26275483

  19. Tritium release properties of neutron-irradiated Be 12Ti

    NASA Astrophysics Data System (ADS)

    Uchida, M.; Ishitsuka, E.; Kawamura, H.

    2002-12-01

    Be 12Ti has a high melting point and good chemical stability and is a promising advanced material for the neutron multiplier of the DEMO reactor that requires temperatures higher than 600 °C in a blanket. To evaluate the tritium inventory in the breeding blanket, a tritium release experiment of neutron-irradiated Be 12Ti with a total fast fluence of about 4×10 20 n/cm 2 ( E>1 MeV) was carried out at 330, 400 and 500 °C. It was clear that tritium could be released easier than from beryllium, and the apparent diffusion coefficient in Be 12Ti was about two orders larger than that in beryllium at 600-100 °C. In addition to the good tritium release property, the swelling calculated from the density change of the specimens up to 1100 °C in this test was smaller than that of beryllium.

  20. Neutron irradiation and compatibility testing of Li 2O

    NASA Astrophysics Data System (ADS)

    Porter, D. L.; Krsul, J. R.; Laug, M. T.; Walters, L. C.; Tetenbaum, M.

    1984-05-01

    A study was made of the neutron irradiation behavior of 6Li-enriched Li 2O in EBR-II. In addition, a stress corrosion study was performed ex-reactor to test the compatibility of Li 2O with a variety of stainless steels. The irradiation tests showed that tritium and helium retention in the Li 2O (˜ 89% dense) lessened with neutron exposure, and the retentions appear to approach a steady-state after ˜ 1% 6Li burnup. The stress corrosion studies, using 316 stainless steel (Ti-modified) and a 35% Ni alloy, showed that stress does not enhance the corrosion, and that dry Li 2O is not significantly corrosive, the LiOH content producing the corrosive effects. Corrosion, in general, was not severe because a passivation in sealed capsules seemed to occur after a time which greatly reduced corrosion rates.

  1. Effects of neutron irradiation on high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Hammerer, John J., Jr.

    1988-06-01

    Neutron irradiation of high temperature superconductors was performed in order to determine the effects of nuclear weapons on these novel materials. This radiation could also be encountered in space radiation belts, fusion reactors and particle accelerators. Fluences used were on the order of 10 to the 18th power fast and thermal neutrons/sq cm. The result of the irradiation was a complete loss of observed superconductivity in YBa2Cu3O7 and ErBa2Cu3O7. A combination of gamma heating of 5 W/g and fast neutron flux imposed serve thermal stress on sample pellets. In two cases, the pellets were reduced to powder. Samples were prepared at the Naval Research Laboratory and the National Research Laboratory and the National Bureau of Standards. They were checked for the Meissner effect using magnetic levitation. The dc four terminal method was used to determine the transition temperature.

  2. Irradiation hardening of pure tungsten exposed to neutron irradiation

    NASA Astrophysics Data System (ADS)

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Kumar, N. A. P. Kiran; Snead, Lance L.; Wirth, Brian D.; Katoh, Yutai

    2016-11-01

    Pure tungsten samples have been neutron irradiated in HFIR at 90-850 °C to 0.03-2.2 dpa. A dispersed barrier hardening model informed by the available microstructure data has been used to predict the hardness. Comparison of the model predictions and the measured Vickers hardness reveals the dominant hardening contribution at various irradiation conditions. For tungsten samples irradiated in HFIR, the results indicate that voids and dislocation loops contributed to the hardness increase in the low dose region (<0.3 dpa), while the formation of intermetallic second phase precipitation, resulting from transmutation, dominates the radiation-induced strengthening beginning with a relatively modest dose (>0.6 dpa). The precipitate contribution is most pronounced for the HFIR irradiations, whereas the radiation-induced defect cluster microstructure can rationalize the entirety of the hardness increase observed in tungsten irradiated in the fast neutron spectrum of Joyo and the mixed neutron spectrum of JMTR.

  3. Fast neutron irradiation for advanced tumors in the pelvis

    SciTech Connect

    Battermann, J.J.; Breur, K.

    1981-08-01

    Since the end of 1975, fast neutron irradiation has been used in the Antoni van Leeuwenhoek Hospital for the treatment of advanced tumors, which had no prospect of cure by other treatment modalities. Fifty-nine patients were irradiated in the pelvic area, 22 for inoperable bladder cancer, 25 for rectal and 12 for gynecological cancer. Treatments were given 5 times per week with a 14 MeV d + T neutron generator. Persisting complete tumor regression was achieved in 11 of 22 bladded patients, 14 of 25 rectum patients and 6 of 12 gynecological patients. Because of unfavorable beam characteristics, 15 of 59 (25%) treated patients had severe radiation-induced intestinal and skin complications.

  4. LET effects following neutron irradiation of lithium formate EPR dosimeters.

    PubMed

    Malinen, Eirik; Waldeland, Einar; Hole, Eli Olaug; Sagstuen, Einar

    2006-03-13

    Lithium formate electron paramagnetic resonance (EPR) dosimeters were irradiated using 60Co gamma-rays or fast neutrons to doses ranging from 5 to 20 Gy and investigated by EPR spectroscopy. Using a polynomial fitting procedure in order to accurately analyze peak-to-peak line widths of first derivative EPR spectra, dosimeters irradiated with neutrons had on average 4.4+/-0.9% broader EPR resonance lines than gamma-irradiated dosimeters. The increase in line width was slightly asymmetrical. Computer simulated first derivative polycrystalline EPR spectra of a *CO2- radical gave very good reconstructions of experimental spectra of irradiated dosimeters. The spectrum simulations could then be used as a tool to investigate the line broadening observed following neutron irradiation. It was shown that an increase in the simulated Lorentzian line width could explain both the observed line broadening and the asymmetrical effect. The ratio of the peak-to-peak amplitude of first derivative EPR spectra obtained at two different microwave powers (20 and 0.5 mW) was 7.8+/-1.2% higher for dosimeters irradiated with neutrons. The dependence of the spectrum amplitude on the microwave power was extensively investigated by fitting observations to an analytical non-linear model incorporating, among others, the spin-lattice (T1) and spin-spin (T2) relaxation times as fitting parameters. Neutron irradiation resulted in a reduction in T(2) in comparison with gamma-irradiation, while a smaller difference in T1 was found. The effects observed indicate increased local radical density following irradiation using high linear energy transfer (LET) neutrons as compared to low LET gamma-irradiation. A fingerprint of the LET may thus be found either by an analysis of the line width or of the dependence of the spectrum amplitude on the microwave power. Lithium formate is therefore a promising material for EPR dosimetry of high LET radiation.

  5. Effect of gas nitriding on CO2 corrosion for 35CrMo steel after surface nanocrystallization.

    PubMed

    Wang, Bingying; Zhou, Shengnan; Wang, Jingjing; Zhao, Bin

    2014-10-01

    This paper studies the influence of ultrasonic surface rolling procession (USRP) and gas nitriding on CO2 corrosion for 35CrMo steel. The microstructure of the nanocrystallized surface caused by USRP and the nitrided layer were studied by means of HRTEM and optical microscope, respectively. High temperature high pressure autoclave was adopted to study the CO2 corrosion behavior of 35CrMo steel. The characteristics of CO2 corrosion scales on 35CrMo steel were investigated by the SEM, EDS and XRD techniques. The experimental results show that after USRP about 250 μm rheological layer forms on the metal surface, and the average grain size is 25 nm. USRP thicken the nitrided layer, 10 hours' gas nitriding at 550 degrees C lower the corrosion rate while the combine of gas nitriding and USRP enhances the corrosion resistance furthest; and the surface nanocrystallization increases the content of Cr and changes the corrosion product film from FeCO3 to FeCO3 and Cr2O3, and from loose crystal structure to amorphous flocculent structure. The corrosion resistance of 35CrMo has been improved significantly by USRP and gas nitriding. PMID:25942927

  6. Direct in vivo inflammatory cell-induced corrosion of CoCrMo alloy orthopedic implant surfaces.

    PubMed

    Gilbert, Jeremy L; Sivan, Shiril; Liu, Yangping; Kocagöz, Sevi B; Arnholt, Christina M; Kurtz, Steven M

    2015-01-01

    Cobalt-chromium-molybdenum (CoCrMo) alloy, used for over five decades in orthopedic implants, may corrode and release wear debris into the body during use. These degradation products may stimulate immune and inflammatory responses in vivo. We report here on evidence of direct inflammatory cell-induced corrosion of human implanted and retrieved CoCrMo implant surfaces. Corrosion morphology on CoCrMo implant surfaces, in unique and characteristic patterns, and the presence of cellular remnants and biological materials intimately entwined with the corrosion indicates direct cellular attack under the cell membrane region of adhered and/or migrating inflammatory cells. Evidence supports a Fenton-like reaction mechanism driving corrosion in which reactive oxygen species are the major driver of corrosion. Using in vitro tests, large increases in corrosion susceptibility of CoCrMo were seen (40-100 fold) when immersed in phosphate buffered saline solutions modified with hydrogen peroxide and hydrochloric acid to represent the chemistry under inflammatory cells. This discovery raises significant new questions about the clinical consequences of such corrosion interactions, the role of patient inflammatory reactions, and the detailed mechanisms at play.

  7. Effect of gas nitriding on CO2 corrosion for 35CrMo steel after surface nanocrystallization.

    PubMed

    Wang, Bingying; Zhou, Shengnan; Wang, Jingjing; Zhao, Bin

    2014-10-01

    This paper studies the influence of ultrasonic surface rolling procession (USRP) and gas nitriding on CO2 corrosion for 35CrMo steel. The microstructure of the nanocrystallized surface caused by USRP and the nitrided layer were studied by means of HRTEM and optical microscope, respectively. High temperature high pressure autoclave was adopted to study the CO2 corrosion behavior of 35CrMo steel. The characteristics of CO2 corrosion scales on 35CrMo steel were investigated by the SEM, EDS and XRD techniques. The experimental results show that after USRP about 250 μm rheological layer forms on the metal surface, and the average grain size is 25 nm. USRP thicken the nitrided layer, 10 hours' gas nitriding at 550 degrees C lower the corrosion rate while the combine of gas nitriding and USRP enhances the corrosion resistance furthest; and the surface nanocrystallization increases the content of Cr and changes the corrosion product film from FeCO3 to FeCO3 and Cr2O3, and from loose crystal structure to amorphous flocculent structure. The corrosion resistance of 35CrMo has been improved significantly by USRP and gas nitriding.

  8. Characteristics of the KUR Heavy Water Neutron Irradiation Facility as a neutron irradiation field with variable energy spectra

    NASA Astrophysics Data System (ADS)

    Sakurai, Yoshinori; Kobayashi, Tooru

    2000-10-01

    The Heavy Water Neutron Irradiation Facility (HWNIF) of the Kyoto University Research Reactor (KUR) was updated in March 1996, mainly for the improvement in neutron capture therapy (NCT). A striking feature of the updated facility is that the energy spectrum of the neutron beam can be controlled from almost pure thermal to epi-thermal, within 5 min by remote control under a continuous reactor operation. This feature is advantageous not only to medical science such as NCT, but also to the other research fields such as physics, engineering, biology, etc. The performance of the updated facility as a neutron irradiation field with variable energy spectra, was characterized. Thermal neutron flux, cadmium ratio, gamma-ray dose rate, etc., at the normal irradiation position for various irradiation modes were determined, mainly on the basis of the measurement using gold activation foils and thermo-luminescent dosimeters (TLDs). The emphasis was on the performance of the new neutron energy spectrum shifter and cadmium thermal neutron filter, that control the mixing ratio of thermal and epi-thermal neutrons, through the change in the heavy water thickness of the spectrum shifter and the aperture size of the cadmium filter. The evaluation of neutron energy spectra at the normal irradiation position was also performed for three representative irradiation modes, in which the neutron intensities are largest of all the irradiation modes. In addition, the irradiation characteristics of two irradiation devices, namely the Irradiation Rail Device and the Remote Patient Carrier, which were updated concurrently with the facility update, were evaluated.

  9. Optical absorption and luminescence studies of fast neutron-irradiated complex oxides for jewellery applications

    NASA Astrophysics Data System (ADS)

    Mironova-Ulmane, N.; Skvortsova, V.; Popov, A. I.

    2016-07-01

    We studied the optical absorption and luminescence of agate (SiO2), topaz (Al2[SiO4](F,OH)2), beryl (Be3Al2Si6O18), and prehnite (Ca2Al(AlSi3O10)(OH)2) doped with different concentrations of transition metal ions and exposed to fast neutron irradiation. The exchange interaction between the impurity ions and the defects arising under neutron irradiation causes additional absorption as well as bands' broadening in the crystals. These experimental results allow us to suggest the method for obtaining new radiation-defect induced jewellery colors of minerals due to neutron irradiation.

  10. Atom probe tomography characterization of neutron irradiated surveillance samples from the R. E. Ginna reactor pressure vessel

    DOE PAGESBeta

    Edmondson, Philip D.; Miller, Michael K.; Powers, Kathy A.; Nanstad, Randy K.

    2015-12-29

    Surveillance samples of a low copper (nominally 0.05 wt.% Cu) forging and a higher copper (0.23 wt.% Cu) submerged arc weld from the R. E. Ginna reactor pressure vessel have been characterized by atom probe tomography (APT) after exposure to three levels of neutron irradiation, i.e., fluences of 1.7, 3.6 and 5.8 × 1023 n.m–2 (E > 1 MeV), and inlet temperatures of ~289 °C (~552 °F). As no copper-enriched precipitates were observed in the low copper forging, and the measured copper content in the ferrite matrix was 0.04± <0.01 at.% Cu, after neutron irradiation to a fluence of 1.7more » × 1023 n.m–3, this copper level was below the solubility limit. A number density of 2 × 1022 m–3 of Ni–, Mn– Si-enriched precipitates with an equivalent radius of gyration of 1.7 ± 0.4 nm were detected in the sample. However, Cu-, Ni-, Mn-enriched precipitates were observed in specimens cut from different surveillance specimens from the same forging material in which the overall measured copper level was 0.08± <0.01 at.% (fluence of 3.6 × 1023 n.m–3) and 0.09± <0.01 at.% Cu (fluence of 5.8 × 1023 n.m–3). Therefore, these slightly higher copper contents were above the solubility limit of Cu under these irradiation conditions. A best fit of all the composition data indicated that the size and number density of the Cu-enriched precipitates increased slightly in both size and number density by additional exposure to neutron irradiation. High number densities of Cu-enriched precipitates were observed in the higher Cu submerged arc weld for all irradiated conditions. The size and number density of the precipitates in the welds were higher than in the same fluence forgings. Some Cu-enriched precipitates were found to have Ni-, Mn- Si-, and P-enriched regions on their surfaces suggesting a preferential nucleation site. Furthermore, atom maps revealed P, Ni, and Mn segregation to, and preferential precipitation of, Cu-enriched precipitates over the surface of a grain

  11. Atom probe tomography characterization of neutron irradiated surveillance samples from the R. E. Ginna reactor pressure vessel

    SciTech Connect

    Edmondson, Philip D.; Miller, Michael K.; Powers, Kathy A.; Nanstad, Randy K.

    2015-12-29

    Surveillance samples of a low copper (nominally 0.05 wt.% Cu) forging and a higher copper (0.23 wt.% Cu) submerged arc weld from the R. E. Ginna reactor pressure vessel have been characterized by atom probe tomography (APT) after exposure to three levels of neutron irradiation, i.e., fluences of 1.7, 3.6 and 5.8 × 1023 n.m–2 (E > 1 MeV), and inlet temperatures of ~289 °C (~552 °F). As no copper-enriched precipitates were observed in the low copper forging, and the measured copper content in the ferrite matrix was 0.04± <0.01 at.% Cu, after neutron irradiation to a fluence of 1.7 × 1023 n.m–3, this copper level was below the solubility limit. A number density of 2 × 1022 m–3 of Ni–, Mn– Si-enriched precipitates with an equivalent radius of gyration of 1.7 ± 0.4 nm were detected in the sample. However, Cu-, Ni-, Mn-enriched precipitates were observed in specimens cut from different surveillance specimens from the same forging material in which the overall measured copper level was 0.08± <0.01 at.% (fluence of 3.6 × 1023 n.m–3) and 0.09± <0.01 at.% Cu (fluence of 5.8 × 1023 n.m–3). Therefore, these slightly higher copper contents were above the solubility limit of Cu under these irradiation conditions. A best fit of all the composition data indicated that the size and number density of the Cu-enriched precipitates increased slightly in both size and number density by additional exposure to neutron irradiation. High number densities of Cu-enriched precipitates were observed in the higher Cu submerged arc weld for all irradiated conditions. The size and number density of the precipitates in the welds were higher than in the same fluence forgings. Some Cu-enriched precipitates were found to have Ni-, Mn- Si-, and P-enriched regions on their surfaces suggesting a preferential nucleation site. Furthermore, atom maps revealed P, Ni, and Mn

  12. Atom probe tomography characterization of neutron irradiated surveillance samples from the R. E. Ginna reactor pressure vessel

    NASA Astrophysics Data System (ADS)

    Edmondson, P. D.; Miller, M. K.; Powers, K. A.; Nanstad, R. K.

    2016-03-01

    Surveillance samples of a low copper (nominally 0.05 wt.% Cu) forging and a higher copper (0.23 wt.% Cu) submerged arc weld from the R. E. Ginna reactor pressure vessel have been characterized by atom probe tomography (APT) after exposure to three levels of neutron irradiation, i.e., fluences of 1.7, 3.6 and 5.8 × 1023 n.m-2 (E > 1 MeV), and inlet temperatures of ∼289 °C (∼552 °F). As no copper-enriched precipitates were observed in the low copper forging, and the measured copper content in the ferrite matrix was 0.04± <0.01 at.% Cu, after neutron irradiation to a fluence of 1.7 × 1023 n.m-3, this copper level was below the solubility limit. A number density of 2 × 1022 m-3 of Ni-, Mn- Si-enriched precipitates with an equivalent radius of gyration of 1.7 ± 0.4 nm were detected in the sample. However, Cu-, Ni-, Mn-enriched precipitates were observed in specimens cut from different surveillance specimens from the same forging material in which the overall measured copper level was 0.08± <0.01 at.% (fluence of 3.6 × 1023 n.m-3) and 0.09± <0.01 at.% Cu (fluence of 5.8 × 1023 n.m-3). Therefore, these slightly higher copper contents were above the solubility limit of Cu under these irradiation conditions. A best fit of all the composition data indicated that the size and number density of the Cu-enriched precipitates increased slightly in both size and number density by additional exposure to neutron irradiation. High number densities of Cu-enriched precipitates were observed in the higher Cu submerged arc weld for all irradiated conditions. The size and number density of the precipitates in the welds were higher than in the same fluence forgings. Some Cu-enriched precipitates were found to have Ni-, Mn- Si-, and P-enriched regions on their surfaces suggesting a preferential nucleation site. Atom maps revealed P, Ni, and Mn segregation to, and preferential precipitation of, Cu-enriched precipitates over the surface of a grain boundary in the low fluence

  13. Microstructural evolution during solution treatment of Co-Cr-Mo-C biocompatible alloys

    SciTech Connect

    Giacchi, J.V.; Fornaro, O.; Palacio, H.

    2012-06-15

    Three different Co-Cr-Mo-C alloys conforming to ASTM F75 standard were poured in an industrial environment and subjected to a conventional solution treatment at 1225 Degree-Sign C for several time intervals. The microstructural changes and transformations were studied in each case in order to evaluate the way in which treatment time influences the secondary phase fraction and clarify the microstructural changes that could occur. To assess how treatment time affects microstructure, optical microscopy and image analyzer software, scanning electron microscopy and energy dispersion spectrometry analysis were employed. The main phases detected in the as-cast state were: {sigma}-phase, M{sub 6}C, and M{sub 23}C{sub 6} carbides. The latter presented two different morphologies, blocky type and lamellar type. Despite being considered the most detrimental feature to mechanical properties, {sigma}-phase and lamellar carbides dissolution took place in the early stages of solution treatment. M{sub 23}C{sub 6} carbides featured two different behaviors. In the alloy obtained by melting an appropriate quantity of alloyed commercial materials, a decrease in size, spheroidization and transformation into M{sub 6}C carbides were simultaneously observed. In the commercial ASTM F75 alloy, in turn, despite being the same phase, only a marked decrease in precipitates size was noticed. These different behaviors could be ascribed to the initial presence of other phases in the alloy obtained from alloyed materials, such as {sigma}-phase and 'pearlitic' carbides, or to the initial precipitate size which was much larger in the first than in the commercial ASTM F75 alloy studied. M{sub 6}C carbides dissolved directly in the matrix as they could not be detected in samples solution-treated for 15 min. - Highlights: Black-Right-Pointing-Pointer Three different Co-Cr-Mo alloys were poured under an industrial environment. Black-Right-Pointing-Pointer Transformation of existing phases followed during

  14. Dynamic Strain Aging in New Generation Cr-Mo-V Steel for Reactor Pressure Vessel Applications

    NASA Astrophysics Data System (ADS)

    Gupta, C.; Chakravartty, J. K.; Banerjee, S.

    2010-12-01

    A new generation nuclear reactor pressure vessel steel (CrMoV type) having compositional similarities with thick section 3Cr-Mo class of low alloy steels and adapted for nuclear applications was investigated for various manifestations of dynamic strain aging (DSA) using uniaxial tests. The steel investigated herein has undergone quenched and tempered treatment such that a tempered bainite microstructure with Cr-rich carbides was formed. The scope of the uniaxial experiments included tensile tests over a temperature range of 298 K to 873 K (25 °C to 600 °C) at two strain rates (10-3 and 10-4 s-1), as well as suitably designed transient strain rate change tests. The flow behavior displayed serrated flow, negative strain rate sensitivity, plateau behavior of yield, negative temperature ( T), and strain rate left( {dot{\\varepsilon }} right) dependence of flow stress over the temperature range of 523 K to 673 K (250 °C to 400 °C) and strain rate range of 5 × 10-3 s-1 to 3 × 10-6 s-1, respectively. While these trends attested to the presence of DSA, a lack of work hardening and near negligible impairment of ductility point to the fact that manifestations of embrittling features of DSA were significantly enervated in the new generation pressure vessel steel. In order to provide a mechanistic understanding of these unique combinations of manifestations of DSA in the steel, a new approach for evaluation of responsible solutes from strain rate change tests was adopted. From these experiments and calculation of activation energy by application of vacancy-based models, the solutes responsible for DSA were identified as carbon/nitrogen. The lack of embrittling features of DSA in the steel was rationalized as being due to the beneficial effects arising from the presence of dynamic recovery effects, presence of alloy carbides in the tempered bainitic structure, and formation of solute clusters, all of which hinder the possibilities for strong aging of dislocations.

  15. Temperature Effects on the Mechanical Properties of Candidate SNS Target Container Materials after Proton and Neutron Irradiation

    SciTech Connect

    Byun, T.S.

    2001-11-09

    This report presents the tensile properties of EC316LN austenitic stainless steel and 9Cr-2WVTa ferritic/martensitic steel after 800 MeV proton and spallation neutron irradiation to doses in the range 0.54 to 2.53 dpa. Irradiation temperatures were in the range 30 to 100 C. Tensile testing was performed at room temperature (20 C) and 164 C to study the effects of test temperature on the tensile properties. Test materials displayed significant radiation-induced hardening and loss of ductility due to irradiation. The EC316LN stainless steel maintained notable strain-hardening capability after irradiation, while the 9Cr-2WVTa ferritic/martensitic steel posted negative strain hardening. In the EC316LN stainless steel, increasing the test temperature from 20 C to 164 C decreased the strength by 13 to 18% and the ductility by 8 to 36%. The tensile data for the EC316LN stainless steel irradiated in spallation conditions were in line with the values in a database for 316 stainless steels for doses up to 1 dpa irradiated in fission reactors at temperatures below 200 C. However, extra strengthening induced by helium and hydrogen contents is evident in some specimens irradiated to above about 1 dpa. The effect of test temperature for the 9Cr-2WVTa ferritic/martensitic steel was less significant than for the EC316LN stainless steel. In addition, strain-hardening behaviors were analyzed for EC316LN and 316L stainless steels. The strain-hardening rate of the 316 stainless steels was largely dependent on test temperature. It was estimated that the 316 stainless steels would retain more than 1% true stains to necking at 164 C after irradiation to 5 dpa. A calculation using reduction of area (RA) measurements and stress-strain data predicted positive strain hardening during plastic instability.

  16. Short-time reactor neutron irradiation of YSZ prepared using reactive calcination method

    NASA Astrophysics Data System (ADS)

    Izerrouken, M.; Boucheffa, Y.; Souami, S.; Sari, A.; Hammache, A.; Meftah, A.; Nekab, M.

    2006-05-01

    The present work is devoted to study the short-time reactor neutron irradiation of yttria stabilised zirconia (YSZ) at 315 K. The samples were prepared by the reactive calcination method and characterised by X-ray diffraction (XRD) analysis and scanning electronic microscope. The prepared samples were irradiated by reactor neutrons at different exposure times and investigated by XRD analysis. The results obtained show good radiation resistance of YSZ to reactor neutron irradiation.

  17. Effect of neutron energy and fluence on deuterium retention behaviour in neutron irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Fujita, Hiroe; Yuyama, Kenta; Li, Xiaochun; Hatano, Yuji; Toyama, Takeshi; Ohta, Masayuki; Ochiai, Kentaro; Yoshida, Naoaki; Chikada, Takumi; Oya, Yasuhisa

    2016-02-01

    Deuterium (D) retention behaviours for 14 MeV neutron irradiated tungsten (W) and fission neutron irradiated W were evaluated by thermal desorption spectroscopy (TDS) to elucidate the correlation between D retention and defect formation by different energy distributions of neutrons in W at the initial stage of fusion reactor operation. These results were compared with that for Fe2+ irradiated W with various damage concentrations. Although dense vacancies and voids within the shallow region near the surface were introduced by Fe2+ irradiation, single vacancies with low concentration were distributed throughout the sample for 14 MeV neutron irradiated W. Only the dislocation loops were introduced by fission neutron irradiation at low neutron fluence. The desorption peak of D for fission neutron irradiated W was concentrated at low temperature region less than 550 K, but that for 14 MeV neutron irradiated W was extended toward the higher temperature side due to D trapping by vacancies. It can be said that the neutron energy distribution could have a large impact on irradiation defect formation and the D retention behaviour.

  18. Precipitate stability in neutron-irradiated Zircaloy-4

    NASA Astrophysics Data System (ADS)

    Yang, W. J. S.

    1988-09-01

    Zircaloy-4, a zirconium-base alloy used extensively as cladding and core structural materials in water-cooled nuclear reactors, was examined by transmission electron microscopy, after neutron irradiation and postirradiation annealing. Phase instabilities found during irradiation at 561 K include the amorphous transformation and the dissolution of the intermetallic Zr(Fe,Cr) 2. The α-matrix is driven toward a single phase solid solution as the neutron fluence increases. This is evidenced by the continuous dissolution of the precipitate without precipitation of any new phase during irradiation. During postirradiation annealing at 833 K, solute Fe precipitates out particularly at the grain boundaries as Zr-Fe zeta-phase. Recrystallization of the amorphous precipitates occurs at a postirradiation annealing temperature of 1023 K. In general, the observed phenomena of amorphous transformation, precipitate dissolution, reprecipitation and recrystallization reflect the complex solute-point defect interactions in the α-matrix. The continuous solute dissolution during irradiation is expected to have a potential effect on irradiation growth, creep and corrosion properties of the alloy.

  19. Resistivity measurements on the neutron irradiated detector grade silicon materials

    SciTech Connect

    Li, Zheng

    1993-11-01

    Resistivity measurements under the condition of no or low electrical field (electrical neutral bulk or ENB condition) have been made on various device configurations on detector grade silicon materials after neutron irradiation. Results of the measurements have shown that the ENB resistivity increases with neutron fluence ({Phi}{sub n}) at low {phi}{sub n} (<10{sup 13} n/cm{sup 2}) and saturates at a value between 300 and 400 k{Omega}-cm at {phi}{sub n} {approximately}10{sup 13} n/cm{sup 2}. Meanwhile, the effective doping concentration N{sub eff} in the space charge region (SCR) obtained from the C-V measurements of fully depleted p{sup +}/n silicon junction detectors has been found to increase nearly linearly with {phi}{sub n} at high fluences ({phi}{sub n} > 10{sup 13} n/cm{sup 2}). The experimental results are explained by the deep levels crossing the Fermi level in the SCR and near perfect compensation in the ENB by all deep levels, resulting in N{sub eff} (SCR) {ne} n or p (free carrier concentrations in the ENB).

  20. Radioactivity of neutron-irradiated cat's-eye chrysoberyls

    NASA Astrophysics Data System (ADS)

    Tang, S. M.; Tay, T. S.

    1999-04-01

    The recent report of marketing of radioactive chrysoberyl cat's-eyes in South-East Asian markets has led us to use an indirect method to estimate the threat to health these color-enhanced gemstones may pose if worn close to skin. We determined the impurity content of several cat's-eye chrysoberyls from Indian States of Orissa and Kerala using PIXE, and calculated the radioactivity that would be generated from these impurities and the constitutional elements if a chrysoberyl was irradiated by neutrons in a nuclear reactor for color enhancement. Of all the radioactive nuclides that could be created by neutron irradiation, only four ( 46Sc, 51Cr, 54Mn and 59Fe) would not have cooled down within a month after irradiation to the internationally accepted level of specific residual radioactivity of 2 nCi/g. The radioactivity of 46Sc, 51Cr and 59Fe would only fall to this safe limit after 15 months and that of 54Mn could remain above this limit for several years.

  1. Mechanical strength of neutron-irradiated window materials

    NASA Astrophysics Data System (ADS)

    Heidinger, R.

    2002-12-01

    Highly specialised window materials considered for transmission lines in plasma heating and diagnostic systems in nuclear fusion reactors were studied in terms of mechanical strength properties and potential radiation effects introduced by neutron irradiation up to 10 21 n/m 2 ( E>0.1 MeV). Small disks of CVD diamond cut from model windows for high power transmission and from rods of a special fused silica grade (KU1) with radiation-hard optical properties were tested together with disks of commercially available high quality silica grades. Based on a biaxial mechanical test method, the influence of specimen machining could be kept under special control. The results obtained for CVD diamond clearly indicate that median strength values of 400 MPa and high Weibull moduli of 20 can be maintained with structural damage introduced at 10 -4 dpa. For high quality silica grades, median strength levels of 300 MPa were reached in the test geometries applied. However, they tend to be very sensitive to changes in the surface quality. Median values of about 120 MPa and Weibull moduli of 10 can be taken for conservative strength evaluations for spontaneous failure.

  2. The effect of neutron irradiation on silicon carbide fibers

    SciTech Connect

    Newsome, G.A.

    1997-01-01

    Nine types of SiC fiber have been exposed to neutron radiation in the Advanced Test Reactor at 250 C for various lengths of time ranging from 83 to 128 days. The effects of these exposures have been initially determined using scanning electron microscopy. The fibers tested were Nicalon{trademark} CG, Tyranno, Hi-Nicalon{trademark}, Dow Corning SiC, Carborundum SiC, Textron SCS-6, polymethysilane (PMS) derived SiC from the University of Michigan, and two types of MER SiC fiber. This covers a range of fibers from widely used commercial fibers to developmental fibers. Consistent with previous radiation experiments, Nicalon fiber was severely degraded by the neutron irradiation. Similarly, Tyranno suffered severe degradation. The more advanced fibers which approach the composition and properties of SiC performed well under irradiation. Of these, the Carborundum SiC fiber appeared to perform the best. The Hi-Nicalon and Dow Corning Fibers exhibited good general stability, but also appear to have some surface roughening. The MER fibers and the Textron SCS-6 fibers both had carbon cores which adversely influenced the overall stability of the fibers.

  3. Neutron-Irradiated Samples as Test Materials for MPEX

    SciTech Connect

    Ellis, Ronald James; Rapp, Juergen

    2015-10-09

    Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by fast neutron irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. This paper presents assessments of the calculated induced radioactivity and resulting radiation dose rates of a variety of potential fusion reactor plasma-facing materials (such as tungsten). The scientific code packages MCNP and SCALE were used to simulate irradiation of the samples in HFIR including the generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. A challenge of the MPEX project is to minimize the radioactive inventory in the preparation of the samples and the sample dose rates for inclusion in the MPEX facility.

  4. Neutron-Irradiated Samples as Test Materials for MPEX

    DOE PAGESBeta

    Ellis, Ronald James; Rapp, Juergen

    2015-10-09

    Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by fast neutron irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. This paper presents assessments of the calculated induced radioactivity and resulting radiation dose rates of a variety of potential fusion reactor plasma-facing materials (such as tungsten). The scientific code packages MCNP and SCALE were used to simulate irradiation of themore » samples in HFIR including the generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. A challenge of the MPEX project is to minimize the radioactive inventory in the preparation of the samples and the sample dose rates for inclusion in the MPEX facility.« less

  5. Retention of Hydrogen Isotopes in Neutron Irradiated Tungsten

    SciTech Connect

    Yuji Hatano; Masashi Shimada; Yasuhisa Oya; Guoping Cao; Makoto Kobayashi; Masanori Hara; Brad J. Merrill; Kenji Okuno; Mikhail A. Sokolov; Yutai Katoh

    2013-03-01

    To investigate the effects of neutron irradiation on hydrogen isotope retention in tungsten, disk-type specimens of pure tungsten were irradiated in the High Flux Isotope Reactor in Oak Ridge National Laboratory followed by exposure to high flux deuterium (D) plasma in Idaho National Laboratory. The results obtained for low dose n-irradiated specimens (0.025 dpa for tungsten) are reviewed in this paper. Irradiation at coolant temperature of the reactor (around 50 degrees C) resulted in the formation of strong trapping sites for D atoms. The concentrations of D in n-irradiated specimens were ranging from 0.1 to 0.4 mol% after exposure to D plasma at 200 and 500 degrees C and significantly higher than those in non-irradiated specimens because of D-trapping by radiation defects. Deep penetration of D up to a depth of 50-100 µm was observed at 500 degrees C. Release of D in subsequent thermal desorption measurements continued up to 900 degrees C. These results were compared with the behaviour of D in ion-irradiated tungsten, and distinctive features of n-irradiation were discussed.

  6. Morphological changes in neutron irradiated red blood cells.

    PubMed

    Nelson, A C; Wyle, H R

    1985-01-01

    Living human red blood cells (erythrocytes) were irradiated with a beam of thermal neutrons having a thermal neutron flux of 9.4 X 10(9) neutrons/cm2 per sec corresponding to a dose rate of 5 Gray per hour. The neutron beam was obtained from the thermal neutron facility at the MIT Nuclear Reactor and contained some gamma-ray contamination which contributes approximately 8% of the dose effect. Approximately 92% of the dose effect is due to the neutron radiation. Populations of neutron irradiated red blood cells were examined under scanning electron microscopy to observe morphological changes due to the radiation dose. The thermal neutron doses ranged from zero for controls to 75 Gray, and cell populations were examined at various post-irradiation time periods of 10, 48, and 96 h. A four-stage discoid to spheroid shape transformation of the damaged red blood cells was characterized, and the time dependence of each transformation stage was determined for both unirradiated and irradiated cells. The radiation dose caused an initial dose-dependent shift from Stage 1 to Stage 2 with an associated increase in the transformation rate constants. The thermal neutron doses delivered are considered to be in the low dose range for radiation effects on red blood cells, yet the pronounced effects indicate a high relative biological effectiveness (RBE) for thermal neutrons.

  7. PROCESSES FOR SEPARATING AND RECOVERING CONSTITUENTS OF NEUTRON IRRADIATED URANIUM

    DOEpatents

    Connick, R.E.; Gofman, J.W.; Pimentel, G.C.

    1959-11-10

    Processes are described for preparing plutonium, particularly processes of separating plutonium from uranium and fission products in neutron-irradiated uraniumcontaining matter. Specifically, plutonium solutions containing uranium, fission products and other impurities are contacted with reducing agents such as sulfur dioxide, uranous ion, hydroxyl ammonium chloride, hydrogen peroxide, and ferrous ion whereby the plutoninm is reduced to its fluoride-insoluble state. The reduced plutonium is then carried out of solution by precipitating niobic oxide therein. Uranium and certain fission products remain behind in the solution. Certain other fission products precipitate along with the plutonium. Subsequently, the plutonium and fission product precipitates are redissolved, and the solution is oxidized with oxidizing agents such as chlorine, peroxydisulfate ion in the presence of silver ion, permanganate ion, dichromate ion, ceric ion, and a bromate ion, whereby plutonium is oxidized to the fluoride-soluble state. The oxidized solution is once again treated with niobic oxide, thus precipitating the contamirant fission products along with the niobic oxide while the oxidized plutonium remains in solution. Plutonium is then recovered from the decontaminated solution.

  8. Irradiation hardening of pure tungsten exposed to neutron irradiation

    DOE PAGESBeta

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Kumar, N. A. P. Kiran; Snead, Lance L.; Wirth, Brian D.; Katoh, Yutai

    2016-08-26

    In this paper, pure tungsten samples have been neutron irradiated in HFIR at 90–850 °C to 0.03–2.2 dpa. A dispersed barrier hardening model informed by the available microstructure data has been used to predict the hardness. Comparison of the model predictions and the measured Vickers hardness reveals the dominant hardening contribution at various irradiation conditions. For tungsten samples irradiated in HFIR, the results indicate that voids and dislocation loops contributed to the hardness increase in the low dose region (<0.3 dpa), while the formation of intermetallic second phase precipitation, resulting from transmutation, dominates the radiation-induced strengthening beginning with a relativelymore » modest dose (>0.6 dpa). Finally, the precipitate contribution is most pronounced for the HFIR irradiations, whereas the radiation-induced defect cluster microstructure can rationalize the entirety of the hardness increase observed in tungsten irradiated in the fast neutron spectrum of Joyo and the mixed neutron spectrum of JMTR.« less

  9. In vitro biocorrosion of Co-Cr-Mo implant alloy by macrophage cells.

    PubMed

    Lin, Hsin-Yi; Bumgardner, Joel D

    2004-11-01

    We hypothesized that macrophage cells and their released reactive chemical species (RCS) affect Co-Cr-Mo alloy's corrosion properties and that alloy corrosion products change macrophage cell behavior. A custom cell culture corrosion cell was used to evaluate how culture medium, cells, and RCS altered alloy corrosion in 3-day tests. Corrosion was evaluated by measuring total charge transfer at a constant potential using a potentiostat and metal ion release by atomic emission spectroscopy. Viability, proliferation, and NO (nitric oxide) and IL-1beta (interlukin-1beta) release were used to assess cellular response to alloy corrosion products. In the presence of activated cells, total charge transfers and Co ion release were the lowest (p < 0.05). This was attributed to an enhancement of the surface oxide by RCS. Cr and Mo release were not different between cells and activated cells. Low levels of metal ions did not affect cell viability, proliferation, or NO release, though IL-1beta released from the activated cells was higher on the alloy compared to the controls. These data support the hypothesis that macrophage cells and their RCS affect alloy corrosion. Changes in alloy corrosion by cells may be important to the development of host responses to the alloy and its corrosion products.

  10. The Kinetics of Metadynamic Recrystallization in a Ni-Cr-Mo-Based Superalloy Hastelloy C-276

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Zhang, Liwen; Shen, Wenfei; Liu, Cuiru; Xia, Yingnan

    2016-02-01

    The metadynamic recrystallization (MDRX) behavior of a typical Ni-Cr-Mo-based superalloy Hastelloy C-276 was investigated using two-stage isothermal compression tests on a Gleeble thermal-mechanical simulator in the temperature range of 1050-1200 °C, the strain rate range of 0.1-5.0 s-1, the strains of 0.32, 0.45, and 0.6 at the first stage of compression, and the interval times of 0.5-30 s. The results show that the microstructure and the stress-strain relation of the studied superalloy vary during the interruption period due to the occurrence of MDRX. The MDRX softening fraction and recrystallized grain size increase rapidly with the increasing of interval time, deformation temperature, and strain rate. The effect of strain at the first stage of compression on MDRX is less pronounced. The kinetics of MDRX softening was established based on the flow stress curves, and the apparent activation energy of MDRX of Hastelloy C-276 is evaluated as 241 kJ/mol.

  11. KINETICS OF CATHODIC REDUCTION OF OXYGEN ON NI-CR-MO-W ALLOY

    SciTech Connect

    NA

    2006-04-06

    Ni-Cr-Mo-W alloys (C-group alloys) are well known as materials with very high Corrosion resistance in very aggressive environments, an asset that has motivated the selection of Alloy 22 as a waste package material in the Yucca Mountain Project for the long-term geologic disposal of spent nuclear fuel and other high-level radioactive wastes. The aim of this project is to elucidate the corrosion performance of Alloy 22 under aggressive conditions and to provide a conceptual understanding and parameter data base that could act as a basis for modeling the corrosion performance of waste packages under Yucca Mountain conditions. A key issue in any corrosion process is whether or not the kinetics of the cathodic reactions involved can support a damaging rate of anodic metal (alloy) dissolution. Under Yucca Mountain conditions the primary oxidant available to drive corrosion (most likely in the form of crevice, or under-deposit, corrosion) will be oxygen. Here, we present results on the kinetics of oxygen reduction at the Alloy 22/solution interface.

  12. Structural and electronic properties of XSi{sub 2} (X = Cr, Mo, and W)

    SciTech Connect

    Shugani, Mani; Aynyas, Mahendra; Sanyal, S. P.

    2015-07-15

    The structural and electronic properties of metal silicides XSi{sub 2} (X = Cr, Mo, and W), which crystallize in tetragonal structure, are investigated systematically using the first-principle density functional theory. The total energies are computed as a function of volume and fitted to the Birch equation of state. The ground-state properties such as equilibrium lattice constants a{sub 0} and c{sub 0}, bulk modulus B, its pressure derivative B, B′, and the density of states at the Fermi level, N(E{sub F}), are calculated and compared with other experimental and theoretical results, showing good agreement. The calculated band structure indicates that XSi{sub 2} compounds are semimetallic in nature. From the present study, we predict the structural and electronic properties of CrSi{sub 2} in the tetragonal phase and indicate that CrSi{sub 2} is energetically more stable than MoSi{sub 2} and WSi{sub 2}. Analyzing the bonding properties of the three metal silicides, we observe that WSi{sub 2} has a strong covalent bonding due to W 5d electrons.

  13. Rotational Conformers of Group VI Metal (Cr, Mo, and w) Bis(mesitylene) Sandwich Complexes

    NASA Astrophysics Data System (ADS)

    Kumari, Sudesh; Yang, Dong-Sheng

    2010-06-01

    Group VI metal bis(mesitylene) sandwich complexes were produced by interactions between laser-vaporized metal atoms and mesitylene vapor in pulsed molecular beams, identified by photoionization time-of-flight mass spectrometry, and studied by pulsed-field-ionization zero-electron-kinetic-energy spectroscopy and density functional theory calculations. Although transition metal bis(arene) sandwiches may adopt eclipsed and staggered conformations, the group VI metal bis(mesitylene) complexes were determined to be in the eclipsed form. In this configuration, two rotational conformers, with methyl group dihedral angles of 0° and 60°, were identified for each complex. The adiabatic ionization energies of the 0° and 60° rotamers were measured to be 40557/40359, 42138/41697, and 41452/41000 cm-1 for the Cr, Mo, and W complexes, with the uncertainty of ˜{5 cm-1}. The ground electronic states of the 0°(D3h)/60° (D3d) rotamers are 1A'1/ 1A1g in the neutral form and ^2A'1/2A1g in the ionized form.

  14. Structural characterization of biomedical Co-Cr-Mo components produced by direct metal laser sintering.

    PubMed

    Barucca, G; Santecchia, E; Majni, G; Girardin, E; Bassoli, E; Denti, L; Gatto, A; Iuliano, L; Moskalewicz, T; Mengucci, P

    2015-03-01

    Direct metal laser sintering (DMLS) is a technique to manufacture complex functional mechanical parts from a computer-aided design (CAD) model. Usually, the mechanical components produced by this procedure show higher residual porosity and poorer mechanical properties than those obtained by conventional manufacturing techniques. In this work, a Co-Cr-Mo alloy produced by DMLS with a composition suitable for biomedical applications was submitted to hardness measurements and structural characterization. The alloy showed a hardness value remarkably higher than those commonly obtained for the same cast or wrought alloys. In order to clarify the origin of this unexpected result, the sample microstructure was investigated by X-ray diffraction (XRD), electron microscopy (SEM and TEM) and energy dispersive microanalysis (EDX). For the first time, a homogeneous microstructure comprised of an intricate network of thin ε (hcp)-lamellae distributed inside a γ (fcc) phase was observed. The ε-lamellae grown on the {111}γ planes limit the dislocation slip inside the γ (fcc) phase, causing the measured hardness increase. The results suggest possible innovative applications of the DMLS technique to the production of mechanical parts in the medical and dental fields.

  15. Fatigue features study on the crankshaft material of 42CrMo steel using acoustic emission

    NASA Astrophysics Data System (ADS)

    Shi, Yue; Dong, Lihong; Wang, Haidou; Li, Guolu; Liu, Shenshui

    2016-09-01

    Crankshaft is regarded as an important component of engines, and it is an important application of remanufacturing because of its high added value. However, the fatigue failure research of remanufactured crankshaft is still in its primary stage. Thus, monitoring and investigating the fatigue failure of the remanufacturing crankshaft is crucial. In this paper, acoustic emission (AE) technology and machine vision are used to monitor the four-point bending fatigue of 42CrMo, which is the material of crankshaft. The specimens are divided into two categories, namely, pre-existing crack and non-preexisting crack, which simulate the crankshaft and crankshaft blank, respectively. The analysis methods of parameter-based AE techniques, wavelet transform (WT) and SEM analysis are combined to identify the stage of fatigue failure. The stage of fatigue failure is the basis of using AE technology in the field of remanufacturing crankshafts. The experiment results show that the fatigue crack propagation style is a transgranular fracture and the fracture is a brittle fracture. The difference mainly depends on the form of crack initiation. Various AE signals are detected by parameter analysis method. Wavelet threshold denoising and WT are combined to extract the spectral features of AE signals at different fatigue failure stages.

  16. Microstructure and phase evolution in laser clad chromium carbide-NiCrMoNb

    NASA Astrophysics Data System (ADS)

    Venkatesh, L.; Samajdar, I.; Tak, Manish; Doherty, Roger D.; Gundakaram, Ravi C.; Prasad, K. Satya; Joshi, S. V.

    2015-12-01

    Microstructural development in laser clad layers of Chromium carbide (CrxCy)-NiCrMoNb on SA 516 steel has been investigated. Although the starting powder contained both Cr3C2 and Cr7C3, the clad layers showed only the presence of Cr7C3. Microtexture measurements by electron back scattered diffraction (EBSD) revealed primary dendritic Cr7C3 with Ni rich FCC metallic phase being present in the interdendritic spaces. Further annealing of the laser clad layers and furnace melting of the starting powder confirmed that Cr7C3 is the primary as well as stable carbide phase in this multi component system. Increase in laser power and scanning speed progressively reduced carbide content in the laser clad layers. Increased scanning speed, which enhances the cooling rate, also led to reduction in the secondary arm spacing (λ2) of the Cr7C3 dendrites. The clad layer hardness increased with carbide content and with decreased dendrite arm spacing.

  17. Investigation of mechanical properties for open cellular structure CoCrMo alloy fabricated by selective laser melting process

    NASA Astrophysics Data System (ADS)

    Azidin, A.; Taib, Z. A. M.; Harun, W. S. W.; Che Ghani, S. A.; Faisae, M. F.; Omar, M. A.; Ramli, H.

    2015-12-01

    Orthodontic implants have been a major focus through mechanical and biological performance in advance to fabricate shape of complex anatomical. Designing the part with a complex mechanism is one of the challenging process and addition to achieve the balance and desired mechanical performance brought to the right manufacture technique to fabricate. Metal additive manufacturing (MAM) is brought forward to the newest fabrication technology in this field. In this study, selective laser melting (SLM) process was utilized on a medical grade cobalt-chrome molybdenum (CoCrMo) alloy. The work has focused on mechanical properties of the CoCrMo open cellular structures samples with 60%, 70%, and 80% designed volume porosity that could potentially emulate the properties of human bone. It was observed that hardness values decreased as the soaking time increases except for bottom face. For compression test, 60% designed volume porosity demonstrated highest ultimate compressive strength compared to 70% and 80%.

  18. Towards near-permanent CoCrMo prosthesis surface by combining micro-texturing and low temperature plasma carburising.

    PubMed

    Dong, Yangchun; Svoboda, Petr; Vrbka, Martin; Kostal, David; Urban, Filip; Cizek, Jan; Roupcova, Pavla; Dong, Hanshan; Krupka, Ivan; Hartl, Martin

    2015-03-01

    An advanced surface engineering process combining micro-texture with a plasma carburising process was produced on CoCrMo femoral head, and their tribological properties were evaluated by the cutting-edge pendulum hip joint simulator coupled with thin film colorimetric interferometry. FESEM and GDOES showed that precipitation-free C S-phase with a uniform case depth of 10μm was formed across the micro-textures after duplex treatment. Hip simulator tests showed that the friction coefficient was reduced by 20% for micro-metre sized texture, and the long-term tribological property of microtexture was enhanced by the C-supersaturated crystalline microstructure formed on the surface of duplex treated CoCrMo, thereby enhancing biotribological durability significantly. In-situ colorimetric interferometry confirmed that the maximum film thickness around texture area was 530nm, indicating that the additional lubricant during sliding motion might provide exceptional bearing life. PMID:26594781

  19. In vivo electrochemical corrosion study of a CoCrMo biomedical alloy in human synovial fluids.

    PubMed

    Igual Munoz, A; Schwiesau, J; Jolles, B M; Mischler, S

    2015-07-01

    The present study was initiated with the aim to assess the in vivo electrochemical corrosion behaviour of CoCrMo biomedical alloys in human synovial fluids in an attempt to identify possible patient or pathology specific effects. For this, electrochemical measurements (open circuit potential OCP, polarization resistance Rp, potentiodynamic polarization curves, electrochemical impedance spectroscopy EIS) were carried out on fluids extracted from patients with different articular pathologies and prosthesis revisions. Those electrochemical measurements could be carried out with outstanding precision and signal stability. The results show that the corrosion behaviour of CoCrMo alloy in synovial fluids not only depends on material reactivity but also on the specific reactions of synovial fluid components, most likely involving reactive oxygen species. In some patients the latter were found to determine the whole cathodic and anodic electrochemical response. Depending on patients, corrosion rates varied significantly between 50 and 750 mg dm(-2)year(-1).

  20. Properties, processing of and experience with the steel X20 CrMo(W)V 12 1

    SciTech Connect

    Leich, K.E. ); Jesper, H. , Dortmund ); Kautz, H.R. )

    1990-01-01

    Considering the hot yield point and the creep rupture strength of X20 CrMo(W)V 12 1 (short: X20) the wall thickness in the temperature range 520-560{degrees}C is lower in comparison with low alloy heat-resistant steels and high-temperature steels. This is especially important with respect to headers, forgings, and piping. As a result, X20 CrMo(W)V 12 1 has become indispensable for large power plant units. Processing of the material, including welding, can be satisfactorily performed by competent manufactures. The excellent ductility of X20 in the creep range and the capability to absorb additional stresses prevented creep damage in forgings and welds. With the use of X20 for headers, forgings, and turbine piping the wall thickness can be reduced to such an extent that power plant units can be operated in the intermediate load range and in cycling mode.

  1. Direct In Vivo Inflammatory Cell-Induced Corrosion of CoCrMo Alloy Orthopedic Implant Surfaces

    PubMed Central

    Gilbert, Jeremy L.; Sivan, Shiril; Liu, Yangping; Kocagöz, Sevi; Arnholt, Christina; Kurtz, Steven M.

    2014-01-01

    Cobalt-chromium-molybdenum alloy, used for over four decades in orthopedic implants, may corrode and release wear debris into the body during use. These degradation products may stimulate immune and inflammatory responses in vivo. We report here on evidence of direct inflammatory cell-induced corrosion of human implanted and retrieved CoCrMo implant surfaces. Corrosion morphology on CoCrMo implant surfaces, in unique and characteristic patterns, and the presence of cellular remnants and biological materials intimately entwined with the corrosion indicates direct cellular attack under the cell membrane region of adhered and/or migrating inflammatory cells. Evidence supports a Fenton-like reaction mechanism driving corrosion in which reactive oxygen species are the major driver of corrosion. Using in vitro tests, large increases in corrosion susceptibility of CoCrMo were seen (40 to 100 fold) when immersed in phosphate buffered saline solutions modified with hydrogen peroxide and HCl to represent the chemistry under inflammatory cells. This discovery raises significant new questions about the clinical consequences of such corrosion interactions, the role of patient inflammatory reactions, and the detailed mechanisms at play. PMID:24619511

  2. Manufacturing of 9CrMoCoB Steel of Large Ingot with Homogeneity by ESR Process

    NASA Astrophysics Data System (ADS)

    Kim, D. S.; Lee, G. J.; Lee, M. B.; Hur, J. I.; Lee, J. W.

    2016-07-01

    In case of 9CrMoCoB (COST FB2) steel, equilibrium relation between [B]/[Si] ratio and (B2O3)/(SiO2) ratio is very important to control [Si] and [B] in optimum range. Therefore, in this work, to investigate the thermodynamic equilibrium relation between [B]/[Si] ratio and (B2O3)/(SiO2) ratio, pilot ESR experiments of 9CrMoCoB steel were carried out using the CaF2-CaO-Al2O3-SiO2-B2O3 slag system according to change of Si content in electrode and B2O3 content in the slag. Furthermore, through the test melting of the 20ton-class ESR ingot, the merits and demerits of soft arcing were investigated. From these results, it is concluded that oxygen content in the ESR ingot decrease with decreasing SiO2 content in the slag, relation function between [B]/[Si] ratio and (B2O3)/(SiO2) ratio derived by Pilot ESR test shows a good agreement as compared to the calculated line with a same slope and soft arcing makes interior and surface quality of ingot worse. With the optimized ESR conditions obtained from the present study, a 1000mm diameter (20 tons) and 2200mm diameter (120ton) 9CrMoCoB steel of the ESR ingot were successfully manufactured with good homogeneity by the ESR process.

  3. A nondestructive method for estimation of the fracture toughness of CrMoV rotor steels based on ultrasonic nonlinearity.

    PubMed

    Jeong, Hyunjo; Nahm, Seung-Hoon; Jhang, Kyung-Young; Nam, Young-Hyun

    2003-09-01

    The objective of this paper is to develop a nondestructive method for estimating the fracture toughness (K(IC)) of CrMoV steels used as the rotor material of steam turbines in power plants. To achieve this objective, a number of CrMoV steel samples were heat-treated, and the fracture appearance transition temperature (FATT) was determined as a function of aging time. Nonlinear ultrasonics was employed as the theoretical basis to explain the harmonic generation in a damaged material, and the nonlinearity parameter of the second harmonic wave was the experimental measure used to be correlated to the fracture toughness of the rotor steel. The nondestructive procedure for estimating the K(IC) consists of two steps. First, the correlations between the nonlinearity parameter and the FATT are sought. The FATT values are then used to estimate K(IC) using the K(IC) versus excess temperature (i.e., T-FATT) correlation that is available in the literature for CrMoV rotor steel. PMID:12919690

  4. Effect of Withdrawal Rate and Gd on the Microstructures of Directionally Solidified NiAl-Cr(Mo) Hypereutectic Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Shen, Jun; Zhang, Yun-Peng; Guo, Lan-Lan

    2016-03-01

    The microstructures of Ni-31Al-32Cr-6Mo- xGd hypereutectic alloy were investigated at the withdrawal rates of 10 μm/s, 30 μm/s, and 90 μm/s. For the Gd-free hypereutectic alloy, the Cr(Mo) primary dendrites appear at the beginning of solidification when the withdrawal rate is 10 μm/s. As the solidification proceeds, the Cr(Mo) primary dendrite is eliminated, and the fully eutectic structure can be obtained in the steady-state zone. With increasing the withdrawal rate, the Cr(Mo) primary dendrites decrease gradually, and vanish at 90 μm/s. In addition, at a moderate withdrawal rate (30 μm/s), an optimum addition of Gd content (0.1 wt.%) results in the refinement of the microstructure, including the refinement of the eutectic cells and the intercellular region. Meanwhile, the new white phase ((Al x Gd1- x )2O3) appears in the boundary of the eutectic cells when the Gd content is not less than 0.1 wt.%.

  5. Microstructural evolution in fast-neutron-irradiated austenitic stainless steels

    SciTech Connect

    Stoller, R.E.

    1987-12-01

    The present work has focused on the specific problem of fast-neutron-induced radiation damage to austenitic stainless steels. These steels are used as structural materials in current fast fission reactors and are proposed for use in future fusion reactors. Two primary components of the radiation damage are atomic displacements (in units of displacements per atom, or dpa) and the generation of helium by nuclear transmutation reactions. The radiation environment can be characterized by the ratio of helium to displacement production, the so-called He/dpa ratio. Radiation damage is evidenced microscopically by a complex microstructural evolution and macroscopically by density changes and altered mechanical properties. The purpose of this work was to provide additional understanding about mechanisms that determine microstructural evolution in current fast reactor environments and to identify the sensitivity of this evolution to changes in the He/dpa ratio. This latter sensitivity is of interest because the He/dpa ratio in a fusion reactor first wall will be about 30 times that in fast reactor fuel cladding. The approach followed in the present work was to use a combination of theoretical and experimental analysis. The experimental component of the work primarily involved the examination by transmission electron microscopy of specimens of a model austenitic alloy that had been irradiated in the Oak Ridge Research Reactor. A major aspect of the theoretical work was the development of a comprehensive model of microstructural evolution. This included explicit models for the evolution of the major extended defects observed in neutron irradiated steels: cavities, Frank faulted loops and the dislocation network. 340 refs., 95 figs., 18 tabs.

  6. Swelling of several commercial alloys following high fluence neutron irradiation

    SciTech Connect

    Powell, R.W.; Peterson, D.T.; Zimmerschied, M.K.; Bates, J.F.

    1981-01-01

    Swelling values have been determined for a set of commercial alloys irradiated to a peak fluence of 17.8 x 10/sup 22/ n/cm/sup 2/ (E > 0.1 MeV) over the temperature range of 400 to 650/sup 0/C. The alloys studied fall into three classes: the ferritic alloys AISI 430F, AISI 416, EM-12, H-11 and 2 1/4 Cr-1 Mo; the superalloys Inconel 718 and Inconel X-750; and the refractory alloys TZM and Nb-1 Zr. After irradiation to a peak fluence approaching goal exposures envisioned for advanced fusion reactor first walls, all of the alloys display swelling resistance far superior to cold worked AISI 316. Of the three alloy classes examined the swelling resistance of the ferritics is the least sensitive to composition.

  7. The tribological difference between biomedical steels and CoCrMo-alloys.

    PubMed

    Fischer, Alfons; Weiss, Sabine; Wimmer, Markus A

    2012-05-01

    In orthopedic surgery, different self-mating metal couples are used for sliding wear applications. Despite the fact that in mechanical engineering, self-mating austenitic alloys often lead to adhesion and seizure in biomedical engineering, the different grades of Co-base alloys show good clinical results, e.g., as hip joints. The reason stems from the fact that they generate a so-called tribomaterial during articulation, which consists of a mixture of nanometer small metallic grains and organic substances from the interfacial medium, which act as a boundary lubricant. Even though stainless steel also generate such a tribomaterial, they were ruled out from the beginning already in the 1950s as "inappropriate". On the basis of materials with a clinical track record, this contribution shows that the cyclic creep characteristics within the shear zone underneath the tribomaterial are another important criterion for a sufficient wear behavior. By means of sliding wear and torsional fatigue tests followed by electron microscopy, it is shown that austenitic materials generate wear particles of either nano- or of microsize. The latter are produced by crack initiation and propagation within the shear fatigue zone which is related to the formation of subsurface dislocation cells and, therefore, by the fact that an Ni-containing CrNiMo solid solution allows for wavy-slip. In contrast to this, an Ni-free CrMnMo solid solution with further additions of C and N only shows planar slip. This leads to the formation of nanosize wear particles and distinctly improves the wear behavior. Still, the latter does not fully achieve that of CoCrMo, which also shows a solely planar-slip behavior. This explains why for metallurgical reasons the Ni-containing 316L-type of steels had to fail in such boundary lubricated sliding wear tribosystems. PMID:22498283

  8. The Tribological Difference between Biomedical Steels and CoCrMo-Alloys

    PubMed Central

    Fischer, Alfons; Weiß, Sabine; Wimmer, Markus A.

    2012-01-01

    In orthopedic surgery different self-mating metal couples are used for sliding wear applications. Despite the fact that in mechanical engineering self-mating austenitic alloys often lead to adhesion and seizure in biomedical engineering the different grades of Co-base alloys show good clinical results e.g. as hip joints. The reason stems from the fact that they generate a so-called tribomaterial during articulation, which consists of a mixture of nanometer small metallic grains and organic substances from the interfacial medium, which act as boundary lubricant. Even though stainless steels also generate such a tribomaterial they were ruled out from the beginning already in the 1950 as “inappropriate”. On the basis of materials with a clinical track record this contribution shows that the cyclic creep characteristics within the shear zone underneath the tribomaterial are another important criterion for a sufficient wear behavior. By means of sliding wear and torsional fatigue tests followed by electron microscopy it is shown, that austenitic materials generate wear particles of either nano- or of microsize. The latter are produced by crack initiation and propagation within the shear fatigue zone which is related to the formation of subsurface dislocation cells and, therefore, by the fact that a Ni-containing CrNiMo solid solution allows for wavy-slip. In contrast to this a Ni-free CrMnMo solid solution with further additions of C and N only shows planar slip. This leads to the formation of nanosize wear particles and distinctly improves the wear behavior. Still the latter does not fully achieve that of CoCrMo, which also shows solely planar-slip behavior. This explains why for metallurgical reasons the Ni-containing 316L-type of steels had to fail in such boundary lubricated sliding wear tribosystems. PMID:22498283

  9. The effects of sulfate reducing bacteria on stainless steel and Ni-Cr-Mo alloy weldments

    SciTech Connect

    Petersen, T.A.; Taylor, S.R.

    1995-10-01

    Previous research in this laboratory demonstrated a direct correlation between alloy composition and corrosion susceptibility of stainless steel and Ni-Cr-Mo alloy weldments exposed to lake water augmented with sulfate reducing bacteria (SRB). It was shown that lake water containing an active SRB population reduced the polarization resistance (R{sub p}) on all alloys studied including those with 9% Mo. In addition, preliminary evidence indicated that edge preparation and weld heat input were also important parameters in determining corrosion performance. This prior research, however, looked at ``doctored`` weldments in which the thermal oxide in the heat affected zone was removed. The objectives of the research presented here are to further confirm these observations using as-received welds. The materials examined (listed in increasing alloy content) are 1/4 inch thick plates of 316L, 317L, AL6XN (6% Mo), alloy 625 clad steel, alloy 625, and alloy 686. Materials were welded using the tungsten inert gas (TIG) process in an argon purged environment. In addition, 317L was welded in air to test oxide effects. All samples were prepared for welding by grinding to a V-edge, except the 625 clad steel samples which were prepared using a J-edge. Electrochemical performance of welded samples was monitored in four glass cells which could each allow exposure of 8 samples to the same environment. Two cells contained lake water inoculated with SRS, and two cells contained sterilized lake water. The open circuit potential (E{sub oc}) and R{sub p} was used to correlate corrosion susceptibility and bacterial activity with alloy composition and welding parameters.

  10. Characterization of 14C in Neutron-Irradiated Graphite

    NASA Astrophysics Data System (ADS)

    LaBrier, Daniel Patrick

    A long-term radiological concern regarding irradiated graphite waste is the presence of the radionuclide 14C. Recent studies suggest that a significant portion of 14C contamination present in reactor-irradiated graphite is concentrated on the surface and within near-surface layers. Methods for treating irradiated graphite waste (e.g. pyrolysis, oxidation) in order to remove 14C-bearing species from the bulk graphite are being investigated to lend guidance in optimizing long-term disposal strategies. Characterization studies were performed in order to determine the chemical nature of 14C on irradiated graphite surfaces. Samples of the nuclear-grade graphite NBG-25 were irradiated in a neutron flux of 10 14 n/cm2-s for 360 days at the Advanced Test Reactor (at the Idaho National Laboratory). Surface-sensitive analysis techniques (XPS, ToF-SIMS, SEM/EDS and Raman) were employed to determine the type, location and quantity of specific chemical species and bonds that were present on the surfaces of irradiated graphite samples. Several 14C precursor species were identified on the surfaces of irradiated NBG-25; the quantities of these species decrease at sub-surface depths, which, is consistent with the observation of high concentrations of 14C on the surfaces of graphite reactor components. The elevated presence of surface oxide complexes on irradiated NBG-25 surfaces was attributed directly to neutron irradiation. Pathways for the release of 14C were identified for irradiated NBG-25: carboxyls and lactones (14CO 2), and carbonyls, ethers and quinones (14CO). Increased amounts of C-O and C=O bonding were observed on irradiated NBG-25 surfaces (when compared to unirradiated samples) in the form of interlattice (e.g. ether) and dangling (e.g. carboxyl or quinone) bonds; the quantities of these bond types also decrease at sub-surface depths. The results of this study are consistent with thermal treatment studies that indicate that the primary candidates for the release of

  11. Dosimetry in Thermal Neutron Irradiation Facility at BMRR

    NASA Astrophysics Data System (ADS)

    Hu, J.-P.; Holden, N. E.; Reciniello, R. N.

    2016-02-01

    Radiation dosimetry for Neutron Capture Therapy (NCT) has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF) of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR). In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation facility, a series of innovative designs and major modifications made to enhance the beam intensity and to ease the experimental sampling at BMRR were performed; including (1) in-core fuel addition to increase source strength and balance flux of neutrons towards two ports, (2) out of core moderator remodeling, done by replacing thicker D2O tanks at graphite-shutter interfacial areas, to expedite neutron thermalization, (3) beam shutter upgrade to reduce strayed neutrons and gamma dose, (4) beam collimator redesign to optimize the beam flux versus dose for animal treatment, (5) beam port shielding installation around the shutter opening area (lithium-6 enriched polyester-resin in boxes, attached with polyethylene plates) to reduce prompt gamma and fast neutron doses, (6) sample holder repositioning to optimize angle versus distance for a single organ or whole body irradiation, and (7) holder wall buildup with neutron reflector materials to increase dose and dose rate from scattered thermal neutrons. During the facility upgrade, reactor dosimetry was conducted using thermoluminescent dosimeters TLD for gamma dose estimate, using ion chambers to confirm fast neutron and gamma dose rate, and by the activation of gold-foils with and without cadmium-covers, for fast and thermal neutron flux determination. Based on the combined effect from the size and depth of tumor cells and the location and geometry of dosimeters, the measured flux from cadmium-difference method was 4-7% lower than

  12. Dosimetry in Thermal Neutron Irradiation Facility at BMRR

    SciTech Connect

    Hu, J. P.; Holden, N. E.; Reciniello, R. N.

    2014-05-23

    Radiation dosimetry for Neutron Capture Therapy (NCT) has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF) of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR). In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation facility, a series of innovative designs and major modifications made to enhance the beam intensity and to ease the experimental sampling at BMRR were performed; including (1) in-core fuel addition to increase source strength and balance flux of neutrons towards two ports, (2) out of core moderator remodeling, done by replacing thicker D2O tanks at graphite-shutter interfacial areas, to expedite neutron thermalization, (3) beam shutter upgrade to reduce strayed neutrons and gamma dose, (4) beam collimator redesign to optimize the beam flux versus dose for animal treatment, (5) beam port shielding installation around the shutter opening area (lithium-6 enriched polyester-resin in boxes, attached with polyethylene plates) to reduce prompt gamma and fast neutron doses, (6) sample holder repositioning to optimize angle versus distance for a single organ or whole body irradiation, and (7) holder wall buildup with neutron reflector materials to increase dose and dose rate from scattered thermal neutrons. During the facility upgrade, reactor dosimetry was conducted using thermoluminescent dosimeters TLD for gamma dose estimate, using ion chambers to confirm fast neutron and gamma dose rate, and by the activation of gold-foils with and without cadmium-covers, for fast and thermal neutron flux determination. Based on the combined effect from the size and depth of tumor cells and the location and geometry of dosimeters, the measured flux from cadmium-difference method was 4 - 7

  13. Behaviour of neutron irradiated beryllium during temperature excursions up to and beyond its melting temperature

    NASA Astrophysics Data System (ADS)

    Pajuste, Elina; Kizane, Gunta; Avotiņa, Līga; Zariņš, Artūrs

    2015-10-01

    Beryllium pebble behaviour has been studied regarding the accidental operation conditions of tritium breeding blanket of fusion reactors. Structure evolution, oxidation and thermal properties have been compared for nonirradiated and neutron irradiated beryllium pebbles during thermal treatment in a temperature range from ambient temperature to 1600 K. For neutron irradiated pebbles tritium release process was studied. Methods of temperature programmed tritium desorption (TPD) in combination with thermogravimetry (TG) and temperature differential analysis (TDA), scanning electron microscopy (SEM) in combination with Energy Dispersive X-ray analysis (EDX) have been used. It was found that there are strong relation between tritium desorption spectra and structural evolution of neutron irradiated beryllium. The oxidation rate is also accelerated by the structure damages caused by neutrons.

  14. Ag transport in high temperature neutron irradiated 3C-SiC

    NASA Astrophysics Data System (ADS)

    O'Connell, J. H.; Neethling, J. H.

    2014-02-01

    The effect of high temperature neutron irradiation on the ability of a Pd-Ag mixture to penetrate 3C-SiC has been investigated. Previous work has revealed enhanced Ag transport in SiC in the presence of the fission product Pd. In this work it has been shown that high temperature neutron irradiation leads to enhanced transport of this Pd-Ag mixture as compared to unirradiated material and that both high irradiation temperature and high neutron fluence is required for significant transport enhancement. The results suggest that grain boundary type and misorientation is not significantly altered by high temperature neutron irradiation, suggesting that these characteristics play only a secondary role in Pd-Ag transport.

  15. Progress on performance assessment of ITER enhanced heat flux first wall technology after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Hirai, T.; Bao, L.; Barabash, V.; Chappuis, Ph; Eaton, R.; Escourbiac, F.; Giqcuel, S.; Merola, M.; Mitteau, R.; Raffray, R.; Linke, J.; Loewenhoff, Th; Pintsuk, G.; Wirtz, M.; Boomstra, D.; Magielsen, A.; Chen, J.; Wang, P.; Gervash, A.; Safronov, V.

    2016-02-01

    ITER first wall (FW) panels are irradiated by energetic neutrons during the nuclear phase. Thus, an irradiation and high heat flux testing programme is undertaken by the ITER organization in order to evaluate the effects of neutron irradiation on the performance of enhanced heat flux (EHF) FW components. The test campaign includes neutron irradiation (up to 0.6-0.8 dpa at 200 °C-250 °C) of mock-ups that are representative of the final EHF FW panel design, followed by thermal fatigue tests (up to 4.7 MW m-2). Mock-ups were manufactured by the same manufacturing process as proposed for the series production. After a pre-irradiation thermal screening, eight mock-ups will be selected for the irradiation campaigns. This paper reports the preparatory work of HHF tests and neutron irradiation, assessment results as well as a brief description of mock-up manufacturing and inspection routes.

  16. In vitro Wear Rate and Co Ion Release of Compositionally and Structurally Graded CoCrMo-Ti6Al4V Structures

    PubMed Central

    Dittrick, Stanley; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit

    2010-01-01

    Novel, unitized structures with porous Ti6Al4V alloy on one side and compositionally graded, hard CoCrMo alloy surface on the other side have been fabricated using laser engineered net shaping (LENS™) process. Gradient structures with 50%, 70% and 86% CoCrMo alloy on the top surface showed high hardness in the range of 615 and 957 HV. The gradient structures were evaluated for their in vitro wear rate and Co release up to 3000 m of sliding distance. The wear rate of ultrahigh molecular weight polyethylene and 100% CoCrMo alloy substrates found to depend on the hardness and microstructural features of the counter surface rubbing against them. In general, the wear rate of both the substrates increased with a decrease in the CoCrMo alloy concentration on the top surface of gradient pins. However, the wear rate of gradient pins was lower than 100% CoCrMo alloy pins due to their high hardness. Lowest wear rate in the range of 5.07 to 7.99 × 10−8 mm3/Nm was observed for gradient pins having 86% CoCrMo alloy on the top surface. The amount of Co released, in the range of 0.38 and 0.91 ppm, during in vitro wear testing of gradient structures was comparable to that of 100% CoCrMo alloy (0.25 and 0.77 ppm). Present unitized structures with open porosity on one side and hard, wear resistant surface on the other side can minimize the wear-induced osteolysis and aseptic loosening, and eliminate the need for multiple parts with different compositions for load-bearing implants such as total hip prostheses. PMID:21516206

  17. Carbide Formation and Dissolution in Biomedical Co-Cr-Mo Alloys with Different Carbon Contents during Solution Treatment

    NASA Astrophysics Data System (ADS)

    Mineta, Shingo; Namba, Shigenobu; Yoneda, Takashi; Ueda, Kyosuke; Narushima, Takayuki

    2010-08-01

    The microstructures of as-cast and heat-treated biomedical Co-Cr-Mo (ASTM F75) alloys with four different carbon contents were investigated. The as-cast alloys were solution treated at 1473 to 1548 K for 0 to 43.2 ks. The precipitates in the matrix were electrolytically extracted from the as-cast and heat-treated alloys. An M23C6 type carbide and an intermetallic σ phase (Co(Cr,Mo)) were detected as precipitates in the as-cast Co-28Cr-6Mo-0.12C alloy; an M23C6 type carbide, a σ phase, an η phase (M6C-M12C type carbide), and a π phase (M2T3X type carbide with a β-manganese structure) were detected in the as-cast Co-28Cr-6Mo-0.15C alloy; and an M23C6 type carbide and an η phase were detected in the as-cast Co-28Cr-6Mo-0.25C and Co-28Cr-6Mo-0.35C alloys. After solution treatment, complete precipitate dissolution occurred in all four alloys. Under incomplete precipitate dissolution conditions, the phase and shape of precipitates depended on the heat-treatment conditions and the carbon content in the alloys. The π phase was detected in the alloys with carbon contents of 0.15, 0.25, and 0.35 mass pct after heat treatment at high temperature such as 1548 K for a short holding time of less than 1.8 ks. The presence of the π phase in the Co-Cr-Mo alloys has been revealed in this study for the first time.

  18. Migration and accumulation at dislocations of transmutation helium in austenitic steels upon neutron irradiation

    NASA Astrophysics Data System (ADS)

    Kozlov, A. V.; Portnykh, I. A.

    2016-04-01

    The model of the migration and accumulation at dislocations of transmutation helium and the formation of helium-vacancy pore nuclei in austenitic steels upon neutron irradiation has been proposed. As illustrations of its application, the dependences of the characteristics of pore nuclei on the temperature of neutron irradiation have been calculated. The results of the calculations have been compared with the experimental data in the literature on measuring the characteristics of radiation-induced porosity that arises upon the irradiation of shells of fuel elements of a 16Cr-19Ni-2Mo-2Mn-Si-Ti-Nb-V-B steel in a fast BN600 neutron reactor at different temperatures.

  19. Properties of simulated cosmic matters after gamma-ray and neutron irradiation

    NASA Astrophysics Data System (ADS)

    Koike, K.; Nakagawa, M.; Koike, C.; Chihara, H.; Okada, M.; Matsumura, M.; Awata, T.; Atobe, K.; Takada, J.

    2006-04-01

    Interstellar and circumstellar matter is known to be strongly irradiated by cosmic radiation and several types of cosmic ray particles. The effects of irradiation on simulated interstellar and circumstellar matter such as CaCO3, MgCO3, SiO2 and Al2O3 are investigated. Especially, thermoluminescence (TL) spectra after γ-ray and neutron irradiation are compared carefully. It is shown that the thermoluminescence after neutron irradiation appears significantly in the wavelength of blue region. On the reflectance in infrared region, the irradiation effect appears scarcely.

  20. The optimization study of Bonner sphere in the epi-thermal neutron irradiation field for BNCT.

    PubMed

    Ueda, H; Tanaka, H; Maruhashi, A; Ono, K; Sakurai, Y

    2011-12-01

    The optimization study on the Bonner sphere in the epi-thermal neutron irradiation field for BNCT was done for the moderator material, moderator size, and activation foils as a neutron detector in the sphere. The saturated activity for the activation foil was obtained from the calculated response, and the effective energy range for each Bonner sphere was determined from the saturated activity. We can see that boric acid solution moderator is suitable for the spectrum measurement of a epi-thermal neutron irradiation field.

  1. Irradiation effects in ferritic steels

    NASA Astrophysics Data System (ADS)

    Lechtenberg, Thomas

    1985-08-01

    Since 1979 the Alloy Development for Irradiation Performance (ADIP) task funded by the US Department of Energy has been studying the 2-12Cr class of ferritic steels to establish the feasibility of using them in fusion reactor first wall/breeding blanket (FW/B) applications. The advantages of ferritic steels include superior swelling resistance, low thermal stresses compared to austenitic stainless steels, attractive mechanical properties up to 600°C. and service histories exceeding 100 000 h. These steels are commonly used in a range of microstructural conditions which include ferritic, martensitic. tempered martensitic, bainitic etc. Throughout this paper where the term "ferritic" is used it should be taken to mean any of these microstructures. The ADIP task is studying several candidate alloy systems including 12Cr-1MoWV (HT-9), modified 9Cr-1MoVNb, and dual-phased steels such as EM-12 and 2 {1}/{4}Cr-Mo. These materials are ferromagnetic (FM), body centered cubic (bcc), and contain chromium additions between 2 and 12 wt% and molybdenum additions usually below 2%. The perceived issues associated with the application of this class of steel to fusion reactors are the increase in the ductile-brittle transition temperature (DBTT) with neutron damage, the compatibility of these steels with liquid metals and solid breeding materials, and their weldability. The ferromagnetic character of these steels can also be important in reactor design. It is the purpose of this paper to review the current understanding of these bcc steels and the effects of irradiation. The major points of discussion will be irradiation-induced or -enhanced dimensional changes such as swelling and creep, mechanical properties such as tensile strength and various measurements of toughness, and activation by neutron interactions with structural materials.

  2. Laser deposited coatings of Co-Cr-Mo onto Ti-6Al-4V and SS316L substrates for biomedical applications.

    PubMed

    Wilson, J Michael; Jones, Nolan; Jin, Li; Shin, Yung C

    2013-10-01

    Functionally gradient bio-coating material was built by laser deposition. Co-Cr-Mo material was deposited on a Ti-6Al-4V substrate transitioning from 0% to 100%. Control over the cooling rate is shown to be a key to reduce the effects of thermal expansion differences of the materials. The microstructures and composition of the functionally gradient material (FGM) were characterized using an optical microscope, SEM, EDS, and XRD. EDS results showed a gradual transition to 50% Co-Cr-Mo and ∼100% Co-Cr-Mo on the top layer. XRD analysis showed the absence of a brittle intermetallic phase that forms between Titanium and Cobalt. As the amount of Co-Cr-Mo increased, the microhardness of the FGM samples significantly increased. A comparison was made between Co-Cr-Mo deposited on SS316L substrates as well as Ti-6Al-4V. The bonding strength of the coatings on both substrates was tested and found to meet the ASTM standard requirement.

  3. Effect of proteins on the surface microstructure evolution of a CoCrMo alloy in bio-tribocorrosion processes.

    PubMed

    Wang, Zhongwei; Yan, Yu; Su, Yanjing; Qiao, Lijie

    2016-09-01

    Under tribological contact, the subsurface microstructure of CoCrMo alloys for artificial joint implants can be changed and affect the life and safety of such devices. As one of the most important and abundant components in the synovial fluid, proteins play a key role in affecting the bio-tribocorrosion behaviors of metal implants. The effect of proteins on the subsurface microstructure evolution of a CoCrMo alloy was investigated using a transmission electron microscope (TEM) in this study. The result shows that proteins have two main effects on the subsurface's evolution: forming a multilayered structure and causing severer subsurface deformation. The tribo-film can protect the passive film from scrapping, and then the passive film can reduce or even suppress the stacking fault annihilation by blocking the access to the metal surface. It leads to the stacking fault being diffused towards the deeper area and a strain accumulation in the subsurface, before inducing a severer deformation. On the other hand, the effect of proteins results in the location changing from the top surface to be underneath the top surface, where the maximum frictional shear stress occurs. This can cause a deeper deformation. PMID:27182652

  4. Evolution of Morphology and Composition of the Carbides in Cr-Mo-V Steel after Service Exposure

    NASA Astrophysics Data System (ADS)

    Dong, Jiling; Shin, Keesam; He, Yinsheng; Song, Geewook; Jung, Jinesung

    2011-06-01

    Low alloy Cr-Mo-V steels are usually used in steam power generation units. The evolution of the carbides often leads to embrittlement of the components during elongated service. Therefore, the determination of carbide evolution mechanism during long-time service is important to understand and prevent premature failures such as temper embrittlement. In this study, low alloy Cr-Mo-V steels used as main steam pipes in a thermal power plant were studied after various service times as well as in the as-fabricated condition. Electron microscopic analyses were carried out on extraction replicas to observe and analyze the morphology and composition of the carbides. Predominant plate-like vanadium-rich carbides were observed in the as-fabricated condition. When exposed to on-site service, the V-rich carbides transformed to Mo-rich carbides which have a typical H morphology. The change of morphology and composition of the carbide is mainly due to the gradual depletion of Mo from the solid solution. In addition, a non-destructive carbide extraction method was established for examination of the precipitates in the working turbine rotor.

  5. Evaluation of Varying Ductile Fracture Criteria for 42CrMo Steel by Compressions at Different Temperatures and Strain Rates

    PubMed Central

    Quan, Guo-zheng; Luo, Gui-chang; Mao, An; Liang, Jian-ting; Wu, Dong-sen

    2014-01-01

    Fracturing by ductile damage occurs quite naturally in metal forming processes, and ductile fracture of strain-softening alloy, here 42CrMo steel, cannot be evaluated through simple procedures such as tension testing. Under these circumstances, it is very significant and economical to find a way to evaluate the ductile fracture criteria (DFC) and identify the relationships between damage evolution and deformation conditions. Under the guidance of the Cockcroft-Latham fracture criteria, an innovative approach involving hot compression tests, numerical simulations, and mathematic computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions, which has not been expounded by Cockcroft and Latham. The results show that the maximum damage value appears in the region of upsetting drum, while the minimal value appears in the middle region. Furthermore, DFC of 42CrMo steel at temperature range of 1123~1348 K and strain rate of 0.01~10 s−1 are not constant but change in a range of 0.160~0.226; thus, they have been defined as varying ductile fracture criteria (VDFC) and characterized by a function of temperature and strain rate. In bulk forming operations, VDFC help technicians to choose suitable process parameters and avoid the occurrence of fracture. PMID:24592175

  6. Manufacturing of high-strength Ni-free Co-Cr-Mo alloy rods via cold swaging.

    PubMed

    Yamanaka, Kenta; Mori, Manami; Yoshida, Kazuo; Kuramoto, Koji; Chiba, Akihiko

    2016-07-01

    The strengthening of biomedical metallic materials is crucial to increasing component durability in biomedical applications. In this study, we employ cold swaging as a strengthening method for Ni-free Co-Cr-Mo alloy rods and examine its effect on the resultant microstructures and mechanical properties. N is added to the alloy to improve the cold deformability, and a maximum reduction in area (r) of 42.6% is successfully obtained via cold swaging. The rod strength and ductility increase and decrease, respectively, with increasing cold-swaging reduction r. Further, the 0.2% proof stress at r=42.6% eventually reaches 1900MPa, which is superior to that obtained for the other strengthening methods proposed to date. Such significant strengthening resulting from the cold-swaging process may be derived from extremely large work hardening due to a strain-induced γ (fcc)→ε (hcp) martensitic transformation, with the resultant intersecting ε-martensite plates causing local strain accumulation at the interfaces. The lattice defects (dislocations/stacking faults) inside the ε phase also likely contribute to the overall strength. However, excessive application of strain during the cold-swaging process results in a severe loss in ductility. The feasibility of cold swaging for the manufacture of high-strength Co-Cr-Mo alloy rods is discussed.

  7. Nanoarchitectured Co-Cr-Mo orthopedic implant alloys: nitrogen-enhanced nanostructural evolution and its effect on phase stability.

    PubMed

    Yamanaka, Kenta; Mori, Manami; Chiba, Akihiko

    2013-04-01

    Our previous studies indicate that nitrogen addition suppresses the athermal γ (face-centered cubic, fcc)→ε (hexagonal close-packed, hcp) martensitic transformation of biomedical Co-Cr-Mo alloys and ultimately offers large elongation to failure while maintaining high strength. In the present study, structural evolution and dislocation slip as an elementary process in the martensitic transformation in Co-Cr-Mo alloys were investigated to reveal the origin of their enhanced γ phase stability due to nitrogen addition. Alloy specimens with and without nitrogen addition were prepared. The N-doped alloys had a single-phase γ matrix, whereas the N-free alloys had a γ/ε duplex microstructure. Irrespective of the nitrogen content, dislocations frequently dissociated into Shockley partial dislocations with stacking faults. This indicates that nitrogen has little effect on the stability of the γ phase, which is also predicted by thermodynamic calculations. We discovered short-range ordering (SRO) or nanoscale Cr2N precipitates in the γ matrix of the N-containing alloy specimens, and it was revealed that both SRO and nanoprecipitates function as obstacles to the glide of partial dislocations and consequently significantly affect the kinetics of the γ→ε martensitic transformation. Since the formation of ε martensite plays a crucial role in plastic deformation and wear behavior, the developed nanostructural modification associated with nitrogen addition must be a promising strategy for highly durable orthopedic implants.

  8. Evaluation of varying ductile fracture criteria for 42CrMo steel by compressions at different temperatures and strain rates.

    PubMed

    Quan, Guo-zheng; Luo, Gui-chang; Mao, An; Liang, Jian-ting; Wu, Dong-sen

    2014-01-01

    Fracturing by ductile damage occurs quite naturally in metal forming processes, and ductile fracture of strain-softening alloy, here 42CrMo steel, cannot be evaluated through simple procedures such as tension testing. Under these circumstances, it is very significant and economical to find a way to evaluate the ductile fracture criteria (DFC) and identify the relationships between damage evolution and deformation conditions. Under the guidance of the Cockcroft-Latham fracture criteria, an innovative approach involving hot compression tests, numerical simulations, and mathematic computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions, which has not been expounded by Cockcroft and Latham. The results show that the maximum damage value appears in the region of upsetting drum, while the minimal value appears in the middle region. Furthermore, DFC of 42CrMo steel at temperature range of 1123~1348 K and strain rate of 0.01~10 s(-1) are not constant but change in a range of 0.160~0.226; thus, they have been defined as varying ductile fracture criteria (VDFC) and characterized by a function of temperature and strain rate. In bulk forming operations, VDFC help technicians to choose suitable process parameters and avoid the occurrence of fracture. PMID:24592175

  9. Evaluation of varying ductile fracture criteria for 42CrMo steel by compressions at different temperatures and strain rates.

    PubMed

    Quan, Guo-zheng; Luo, Gui-chang; Mao, An; Liang, Jian-ting; Wu, Dong-sen

    2014-01-01

    Fracturing by ductile damage occurs quite naturally in metal forming processes, and ductile fracture of strain-softening alloy, here 42CrMo steel, cannot be evaluated through simple procedures such as tension testing. Under these circumstances, it is very significant and economical to find a way to evaluate the ductile fracture criteria (DFC) and identify the relationships between damage evolution and deformation conditions. Under the guidance of the Cockcroft-Latham fracture criteria, an innovative approach involving hot compression tests, numerical simulations, and mathematic computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions, which has not been expounded by Cockcroft and Latham. The results show that the maximum damage value appears in the region of upsetting drum, while the minimal value appears in the middle region. Furthermore, DFC of 42CrMo steel at temperature range of 1123~1348 K and strain rate of 0.01~10 s(-1) are not constant but change in a range of 0.160~0.226; thus, they have been defined as varying ductile fracture criteria (VDFC) and characterized by a function of temperature and strain rate. In bulk forming operations, VDFC help technicians to choose suitable process parameters and avoid the occurrence of fracture.

  10. Resistivity measurements of neutron-irradiated pure metals and Al-Zn alloys

    NASA Technical Reports Server (NTRS)

    Horak, J. A.

    1968-01-01

    Report presents resistivity measurements and their interpretation for neutron-irradiated pure metals and Al-Zn alloys. The influence of temperature, the role of point defects, and the aging behavior on resistivity are considered. The experimental procedures and results are discussed in detail.

  11. Characterization of the fast neutron irradiation facility of the Portuguese Research Reactor after core conversion.

    PubMed

    Marques, J G; Sousa, M; Santos, J P; Fernandes, A C

    2011-08-01

    The fast neutron irradiation facility of the Portuguese Research Reactor was characterized after the reduction in uranium enrichment and rearrangement of the core configuration. In this work we report on the determination of the hardness parameter and the 1MeV equivalent neutron flux along the facility, in the new irradiation conditions, following ASTM E722 standard.

  12. Electron microscopic studies of damage evolution in fission neutron-irradiated metals

    NASA Astrophysics Data System (ADS)

    Shimomura, Y.; Yoshida, H.; Kiritani, M.; Kitagawa, K.; Yamakawa, K.

    1985-08-01

    The same kinds of specimens of both foil and bulk of metals, as those irradiated previously with D-T neutrons at RTNS-II, were irradiated with fission neutrons at KUR. The irradiations were performed at 20 and 350 K to fluences of 5 × 10 16 and 1 × 10 19 n/cm 2(E > 0.1 MeV), respectively. The results on pure gold are described to exemplify the typical value of cascade defects. A cascade in fission neutron irradiated gold consists of 2.2 small defects on average. This is compared with 6.7 small defects for the fusion neutron irradiation. The cross section for the formation of observed cascade defects is 0.15 barn, which is a twelveth of that in fusion neutron irradiation. The cryotransfer of the thin foil to the electron microscope was carried out to observe the cascade defects at low temperatures. The average size of cascade defects in fission neutron-irradiated gold was much smaller than that in fusion irradiation. The damage evolution in the bulk specimen was also examined.

  13. Comparison of Deuterium Retention for Ion-irradiated and Neutron-irradiated Tungsten

    SciTech Connect

    Yasuhisa Oya; Masashi Shimada; Makoto Kobayashi; Takuji Oda; Masanori Hara; Hideo Watanabe; Yuji Hatano; Pattrick Calderoni; Kenji Okuno

    2011-12-01

    The behavior of D retention for Fe{sup 2+}-irradiated tungsten with a damage of 0.025-3 dpa was compared with that for neutron-irradiated tungsten with 0.025 dpa. The D{sub 2} thermal desorption spectroscopy (TDS) spectra for Fe{sup 2+}-irradiated tungsten consisted of two desorption stages at 450 and 550 K, while that for neutron-irradiated tungsten was composed of three stages and an addition desorption stage was found at 750 K. The desorption rate of the major desorption stage at 550K increased as the displacement damage increased due to Fe{sup 2+} irradiation increasing. In addition, the first desorption stage at 450K was found only for damaged samples. Therefore, the second stage would be based on intrinsic defects or vacancy produced by Fe{sup 2+} irradiation, and the first stage should be the accumulation of D in mono-vacancy and the activation energy would be relatively reduced, where the dislocation loop and vacancy is produced. The third one was found only for neutron irradiation, showing the D trapping by a void or vacancy cluster, and the diffusion effect is also contributed to by the high full-width at half-maximum of the TDS spectrum. Therefore, it can be said that the D{sub 2} TDS spectra for Fe{sup 2+}-irradiated tungsten cannot represent that for the neutron-irradiated one, indicating that the deuterium trapping and desorption mechanism for neutron-irradiated tungsten is different from that for the ion-irradiated one.

  14. Multiscale Modeling of the Deformation of Advanced Ferritic Steels for Generation IV Nuclear Energy

    SciTech Connect

    Nasr M. Ghoniem; Nick Kioussis

    2009-04-18

    The objective of this project is to use the multi-scale modeling of materials (MMM) approach to develop an improved understanding of the effects of neutron irradiation on the mechanical properties of high-temperature structural materials that are being developed or proposed for Gen IV applications. In particular, the research focuses on advanced ferritic/ martensitic steels to enable operation up to 650-700°C, compared to the current 550°C limit on high-temperature steels.

  15. Preselection of Ni-Cr(-Mo) alloys as potential canister materials for vitrified high active nuclear waste by electrochemical testing

    NASA Astrophysics Data System (ADS)

    Bort, H.; Wolf, I.; Leistikow, S.

    1987-07-01

    Several Ni-Cr(-Mo) alloys (Hastelloy C4, Inconel 625, Sanicro 28, Incoloy 825, Inconel 690) were tested by electrochemical methods to characterize their corrosion behavior in chloride containing solutions at various temperatures and pH-values in respect to their application as canister materials for final radioactive waste storage. Especially, Hastelloy C4 was tested by potentiodynamic, potentiostatic and galvanostic measurements. As electrolytes H 2SO 4 solutions were used, as parameters temperature, chloride content and pH-value were varied. All tested alloys showed a clearly limited resistance against pitting corrosion phenomena; under severe conditions even crevice corrosion phenomena were observed. The best corrosion behavior, however, is shown by Hastelloy C4, which has the lowest passivation current density of all tested alloys and the largest potential region with protection against local corrosion phenomena.

  16. Prediction of solidification path and carbide precipitation in Fe-C-V-Cr-Mo-W high speed steels

    NASA Astrophysics Data System (ADS)

    Zhang, Hongwei; Gandin, Charles-André; He, Jicheng; Nakajima, Keiji

    2012-07-01

    The solidification path and precipitation of carbides in the Fe-C-V-Cr-Mo-W high speed steel system are predicted with the help of thermodynamic equilibrium calculations. The Partial Equilibrium (PE) approximation is favoured. According to experimental data for high speed steel samples, the precipitating solidification sequence of carbides, including nature, composition and amount are discussed as a function of the nominal composition of C and V. The results show that the solidification path can be reasonably predicted by the Partial Equilibrium approximation for cooling rate lower than 10 K min-1. The experimental results suffer from the sensitivity limitation of the characterization methods used when the phase fraction becomes too small.

  17. Room Temperature Microstructure and Property Evaluation of a Heat Treated Fully Bainitic 20CrMoVTiB410 Steel

    NASA Astrophysics Data System (ADS)

    Srivatsa, Kulkarni; Srinivas, Perla; Balachandran, G.; Balasubramanian, V.

    2016-10-01

    The room temperature mechanical behavior of the fully bainitic steel grade 20CrMoVTiB410 was studied in the as-quenched and tempered conditions. The hardenability response of the steel during heat treatment was assessed. In the as-quenched condition itself, the steel exhibited a good combination of strength, ductility and toughness. Tempering the quenched steel till to 550°C, showed uniform mechanical properties. Tempering at 650°C showed secondary hardening behaviour, where the highest strength and least impact toughness was observed. Tempering at 700°C showed a sharp decrease in strength but with significant enhancement of toughness. The properties obtained were correlated with the microstructure and phase analysis was established using optical, scanning electron microscope, transmission electron microscope and x-ray diffraction techniques.

  18. Microstructural characterization of low and high carbon CoCrMo alloy nanoparticles produced by mechanical milling

    NASA Astrophysics Data System (ADS)

    Simoes, T. A.; Goode, A. E.; Porter, A. E.; Ryan, M. P.; Milne, S. J.; Brown, A. P.; Brydson, R. M. D.

    2014-06-01

    CoCrMo alloys are utilised as the main material in hip prostheses. The link between this type of hip prosthesis and chronic pain remains unclear. Studies suggest that wear debris generated in-vivo may be related to post-operative complications such as inflammation. These alloys can contain different amounts of carbon, which improves the mechanical properties of the alloy. However, the formation of carbides could become sites that initiate corrosion, releasing ions and/or particles into the human body. This study analysed the mechanical milling of alloys containing both high and low carbon levels in relevant biological media, as an alternative route to generate wear debris. The results show that low carbon alloys produce significantly more nanoparticles than high carbon alloys. During the milling process, strain induces an fcc to hcp phase transformation. Evidence for cobalt and molybdenum dissolution in the presence of serum was confirmed by ICP-MS and TEM EDX techniques.

  19. Room Temperature Microstructure and Property Evaluation of a Heat Treated Fully Bainitic 20CrMoVTiB410 Steel

    NASA Astrophysics Data System (ADS)

    Srivatsa, Kulkarni; Srinivas, Perla; Balachandran, G.; Balasubramanian, V.

    2016-08-01

    The room temperature mechanical behavior of the fully bainitic steel grade 20CrMoVTiB410 was studied in the as-quenched and tempered conditions. The hardenability response of the steel during heat treatment was assessed. In the as-quenched condition itself, the steel exhibited a good combination of strength, ductility and toughness. Tempering the quenched steel till to 550°C, showed uniform mechanical properties. Tempering at 650°C showed secondary hardening behaviour, where the highest strength and least impact toughness was observed. Tempering at 700°C showed a sharp decrease in strength but with significant enhancement of toughness. The properties obtained were correlated with the microstructure and phase analysis was established using optical, scanning electron microscope, transmission electron microscope and x-ray diffraction techniques.

  20. Prediction of Mechanical Properties of 25CrMo48V Seamless Tube Using Neural Network Model

    NASA Astrophysics Data System (ADS)

    Sun, Laibo; Zhang, Chuanyou; Wang, Qingfeng; Wang, Mingzhi; Yan, Zesheng

    In this investigation, a neural network model was established to predict mechanical properties of 25CrMo48V seamless tubes. The sensitivity analysis was also performed to estimate the relative significance of each chemical composition in mechanical behavior of steel tubes. The results of this investigation show that there is a good agreement between experimental and predicted values indicating desirable validity of the model. Among those alloying elements, the elements of carbon, silicon and chromium tended to play a more important role in controlling both the yielding strength and the Charpy-V-Notch transverse impact toughness. In comparison, the impurities such as O, N, S and P have a relatively weak impact. More detailed dependences of mechanical properties on each chemical composition in isolation can be revealed using the established model. The well-trained neural network has a great potential in designing tough and ultrahigh-strength seamless tubes and modeling the on-line production parameters.

  1. Effect of Surface Roughness on the Adhesive and Tribological Characteristics of DLC Coating Prepared on Co-Cr-Mo Alloy

    NASA Astrophysics Data System (ADS)

    Sheeja, D.; Tay, B. K.; Lam, H. M.; Ng, S. K.

    The Co-Cr-Mo alloy is extensively used for tribological applications, including orthopaedic components in total joint replacements. High quality diamond-like carbon (DLC) coatings on metal/alloy substrates are of great interest as they are able to protect them from severe wear and thus prolong the life span of the component. Since the roughness of the metal/alloy varies depending on the applications, a study has been carried out to investigate the effect of substrate surface roughness on the microstructure, sliding life, wear-resistance, coefficient of friction, adhension and hardness of DLC coatings prepared on Co-Cr-Mo alloy substrates under the same deposition condition. The microstructure of the films studied using Raman spectroscopy suggests that the film prepared on a smoother surface contains slightly higher fraction of sp3 bonded carbon atoms. The characterization using a pin-on-disk tribometer reveals that, the film prepared on the roughest sample (Ra ~ 0.06 μm) exhibits a very short life span of about 20 cycles compared to the film that is prepared on a relatively smoother surface (Ra ~ 0.02 μm), which exhibits a life span of about 340,000 cycles. In order to investigate the origin of this improved property of the DLC film on the smoother surface, adhesive strength and hardness of the films were studied by using a micro-scratch tester and a Nano-indenter, respectively. The results suggest that the film prepared on the smoother surface exhibits better adhesion (higher critical load) and relatively higher hardness.

  2. Investigations on Freon-assisted atomization of refractory analytes (Cr, Mo, Ti, V) in multielement electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Heinrich, Hans-Joachim; Matschat, Ralf

    2007-08-01

    Premixed 1% Freon in argon inner gas of various composition (CCl 2F 2, CHClF 2, CHF 3) was applied to graphite furnace atomizer to minimize unfavorable effects of carbide formation, such as signal tailing and memory effects in the simultaneous determination of Cr, Mo, Ti and V refractory analytes by electrothermal atomic absorption spectrometry using a multielement atomic absorption spectrometer. The effect of these gaseous additives was investigated when applied separately in atomization, pyrolysis and clean-out steps. The halogenation effects were analytically useful only under the precondition of using Ar-H 2 outer gas to the furnace to all heating steps, and also using this gas in the pre-atomization (drying, pyrolysis) steps. Optimum analytical performance was obtained when mixtures of 1% Freon in argon were applied just before and during the atomization step at a flow rate of 50 mL min - 1 and 2% hydrogen was used as purge gas. Using optimum conditions, signal tailings and carry-over contamination were reduced effectively and good precision (relative standard deviation below 1%) could be attained. Applying 1% CHClF 2 and an atomization temperature of 2550 °C, the characteristic masses obtained for simple aqueous solutions were 8.8 pg for Cr, 17 pg for Mo, 160 pg for Ti, and 74 pg for V. The limits of detection were 0.05, 0.2, 2.3 and 0.5 μg L - 1 for Cr, Mo, Ti and V, respectively. The developed method was applied to the analysis of digests of advanced ceramics. The accuracy of the procedure was confirmed by analyzing the certified reference material ERM-ED 102 (Boron Carbide Powder) and a silicon nitride powder distributed in the inter-laboratory comparison CCQM-P74.

  3. Study of the defects in oxygen implanted silicon subjected to neutron irradiation and high pressure annealing

    NASA Astrophysics Data System (ADS)

    Jung, W.; Kaniewska, M.; Misiuk, A.; Londos, C. A.

    2004-07-01

    This paper reports on capacitance measurements on Czochralski-grown and float-zone silicon subjected to oxygen implantation, subsequent neutron irradiation and finally high pressure thermal anneals. The purpose of this work was the study of the effect of irradiation on the formation of thermal donors in silicon. The observed changes in the C-V characteristic curves and profiles are discussed. We found that oxygen-ion implantation followed by neutron irradiation results in shallow and deep level acceptor-like defects formation. Prolonged heat treatment leads to thermal donor generation as usual in Cz-Si annealed at 450°C. The most striking result of the study is finding that high pressure thermal anneals result in extra donor formation. The effects mentioned above may lead to changes in the type of conductivity depending on oxygen content in the material, hydrostatic pressure and an extent of damage caused by the irradiation.

  4. Model of defect reactions and the influence of clustering in pulse-neutron-irradiated Si

    SciTech Connect

    Myers, S. M.; Cooper, P. J.; Wampler, W. R.

    2008-08-15

    Transient reactions among irradiation defects, dopants, impurities, and carriers in pulse-neutron-irradiated Si were modeled taking into account the clustering of the primal defects in recoil cascades. Continuum equations describing the diffusion, field drift, and reactions of relevant species were numerically solved for a submicrometer spherical volume, within which the starting radial distributions of defects could be varied in accord with the degree of clustering. The radial profiles corresponding to neutron irradiation were chosen through pair-correlation-function analysis of vacancy and interstitial distributions obtained from the binary-collision code MARLOWE, using a spectrum of primary recoil energies computed for a fast-burst fission reactor. Model predictions of transient behavior were compared with a variety of experimental results from irradiated bulk Si, solar cells, and bipolar-junction transistors. The influence of defect clustering during neutron bombardment was further distinguished through contrast with electron irradiation, where the primal point defects are more uniformly dispersed.

  5. Detection of previous neutron irradiation and reprocessing of uranium materials for nuclear forensic purposes.

    PubMed

    Varga, Zsolt; Surányi, Gergely

    2009-04-01

    The paper describes novel analytical methods developed for the detection of previous neutron irradiation and reprocessing of illicit nuclear materials, which is an important characteristic of nuclear materials of unknown origin in nuclear forensics. Alpha spectrometry and inductively coupled plasma sector-field mass spectrometry (ICP-SFMS) using solution nebulization and direct, quasi-non-destructive laser ablation as sample introduction were applied for the measurement of trace-level (232)U, (236)U and plutonium isotopes deriving from previous neutron irradiation of uranium-containing nuclear materials. The measured radionuclides and isotope ratios give important information on the raw material used for fuel production and enable confirm the supposed provenance of illicit nuclear material. PMID:19179085

  6. Microstructure of V-4Cr-4Ti following low temperature neutron irradiation

    SciTech Connect

    Rice, P.M.; Snead, L.L.; Alexander, D.J.; Zinkle, S.J.

    1996-12-31

    The V-4Cr-4Ti alloys displays excellent mechanical properties, including a ductile-to-brittle transition temperature (DBTT) below - 200 C in the unirradiated conditions. Samples were fission neutron- irradiated in HFBR to a 0.4 dpa dose at 100-275 C. Mechanical tests showed significant irradiation hardening which increased with irradiation temperature. Charpy impact testing also showed a dramatic increase in DBTT on the order of 100 to 350 C. The mechanical property changes are correlated with preliminary results from TEM analysis of the defect microstructure resulting from the low-dose neutron irradiations. TEM of the irradiated material showed a nearly constant defect density of {approximately}1.6x10{sup 23}m{sup -3}, with an average defect diameter of slightly greater than 3 nm.

  7. Correlation between shear punch and tensile data for neutron-irradiated aluminum alloys

    SciTech Connect

    Hamilton, M.L.; Edwards, D.J.; Toloczko, M.B.

    1995-04-01

    This work was performed to determine whether shear punch and tensile data obtained on neutron irradiated aluminum alloys exhibited the same type of relationship as had been seen in other work and to assess the validity of extrapolating the results to proton-irradiated alloys. This work was also meant to be the first of a series of similar test matrices designed to determine whether the shear punch/tensile relationship varied or was the same for different alloy classes.

  8. The Influence of Composition upon Surface Degradation and Stress Corrosion Cracking of the Ni-Cr-Mo Alloys in Wet Hydrofluoric Acid

    SciTech Connect

    Crook, P; Meck, N S; Rebak, R B

    2006-12-04

    At concentrations below 60%, wet hydrofluoric acid (HF) is extremely corrosive to steels, stainless steels and reactive metals, such as titanium, zirconium, and tantalum. In fact, only a few metallic materials will withstand wet HF at temperatures above ambient. Among these are the nickel-copper (Ni-Cu) and nickel-chromium-molybdenum (Ni-Cr-Mo) alloys. Previous work has shown that, even with these materials, there are complicating factors. For example, under certain conditions, internal attack and stress corrosion cracking (SCC) are possible with the Ni-Cr-Mo alloys, and the Ni-Cu materials can suffer intergranular attack when exposed to wet HF vapors. The purpose of this work was to study further the response of the Ni-Cr-Mo alloys to HF, in particular their external corrosion rates, susceptibility to internal attack and susceptibility to HF-induced SCC, as a function of alloy composition. As a side experiment, one of the alloys was tested in two microstructural conditions, i.e. solution annealed (the usual condition for materials of this type) and long-range ordered (this being a means of strengthening the alloy in question). The study of external corrosion rates over wide ranges of concentration and temperature revealed a strong beneficial influence of molybdenum content. However, tungsten, which is used as a partial replacement for molybdenum in some Ni-Cr-Mo alloys, appears to render the alloys more prone to internal attack. With regard to HF-induced SCC of the Ni-Cr-Mo alloys, this study suggests that only certain alloys (i.e., those containing tungsten) exhibit classical SCC. It was also discovered that high external corrosion rates inhibit HF-induced SCC, presumably due to rapid progression of the external attack front. With regard to the effects of long-range ordering, these were only evident at the highest test temperatures, where the ordered structure exhibited much higher external corrosion rates than the annealed structure.

  9. Large lattice relaxation deep levels in neutron-irradiated GaN

    SciTech Connect

    Li, S.; Zhang, J.D.; Beling, C.D.; Wang, K.; Wang, R.X.; Gong, M.; Sarkar, C.K.

    2005-11-01

    Deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) measurements have been carried out in neutron-irradiated n-type hydride-vapor-phase-epitaxy-grown GaN. A defect center characterized by a DLTS line, labeled as N1, is observed at E{sub C}-E{sub T}=0.17 eV. Another line, labeled as N2, at E{sub C}-E{sub T}=0.23 eV, seems to be induced at the same rate as N1 under irradiation and may be identified with E1. Other defects native to wurtzite GaN such as the C and E2 lines appear to enhance under neutron irradiation. The DLOS results show that the defects N1 and N2 have large Frank-Condon shifts of 0.64 and 0.67 eV, respectively, and hence large lattice relaxations. The as-grown and neutron-irradiated samples all exhibit the persistent photoconductivity effect commonly seen in GaN that may be attributed to DX centers. The concentration of the DX centers increases significantly with neutron dosage and is helpful in sustaining sample conductivity at low temperatures, thus making possible DLTS measurements on N1 an N2 in the radiation-induced deep-donor defect compensated material which otherwise are prevented by carrier freeze-out.

  10. Design of sample carrier for neutron irradiation facility at TRIGA MARK II nuclear reactor

    NASA Astrophysics Data System (ADS)

    Abdullah, Y.; Hamid, N. A.; Mansor, M. A.; Ahmad, M. H. A. R. M.; Yusof, M. R.; Yazid, H.; Mohamed, A. A.

    2013-06-01

    The objective of this work is to design a sample carrier for neutron irradiation experiment at beam ports of research nuclear reactor, the Reaktor TRIGA PUSPATI (RTP). The sample carrier was designed so that irradiation experiment can be performed safely by researchers. This development will resolve the transferring of sample issues faced by the researchers at the facility when performing neutron irradiation studies. The function of sample carrier is to ensure the sample for the irradiation process can be transferred into and out from the beam port of the reactor safely and effectively. The design model used was House of Quality Method (HOQ) which is usually used for developing specifications for product and develop numerical target to work towards and determining how well we can meet up to the needs. The chosen sample carrier (product) consists of cylindrical casing shape with hydraulic cylinders transportation method. The sample placing can be done manually, locomotion was by wheel while shielding used was made of boron materials. The sample carrier design can shield thermal neutron during irradiation of sample so that only low fluencies fast neutron irradiates the sample.

  11. Mechanical and thermal properties of hot pressed CoCrMo-porcelain composites developed for prosthetic dentistry.

    PubMed

    Henriques, B; Gasik, M; Souza, J C M; Nascimento, R M; Soares, D; Silva, F S

    2014-02-01

    In this study, mechanical and thermal properties of CoCrMo-porcelain composites for dental restorations have been evaluated. These metal-ceramic composites were produced by powder metallurgy and hot pressing techniques from the mixtures of metal and ceramic powders with different volume fractions. Young's moduli and the coefficient of thermal expansion of materials were evaluated by dynamic mechanical analysis (DMA) and dilatometry (DIL) tests, respectively. The strength in flexion and shear was measured with a universal test machine and hardness with a respective tester. The microstructures and fracture surfaces were inspected by the means of optical microscopy and Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS). Shear strength, Flexural strength and Young' moduli of ceramic and metal-matrix composites were found to increase with higher metal particles content. The DMA tests performed at different frequencies showed no frequency-dependent features of the materials studied, indicating no viscoelastic behavior. The fracture surfaces analysis suggests the load-transfer mechanism be possibly responsible for this behavior, as the differences in CTE are low enough to cause significant thermal stresses in these materials. The results might be included in a materials properties database for further use for design and optimization of dental restorations.

  12. Temperature-dependent phase-specific deformation mechanisms in a directionally solidified NiAl-Cr(Mo) lamellar composite

    SciTech Connect

    Yu, Dunji; An, Ke; Chen, Xu; Bei, Hongbin

    2015-10-09

    Phase-specific thermal expansion and mechanical deformation behaviors of a directionally solidified NiAl–Cr(Mo) lamellar in situ composite were investigated by using real-time in situ neutron diffraction during compression at elevated temperatures up to 800 °C. Tensile and compressive thermal residual stresses were found to exist in the NiAl phase and Crss (solid solution) phase, respectively. Then, based on the evolution of lattice spacings and phase stresses, the phase-specific deformation behavior was analyzed qualitatively and quantitatively. Moreover, estimates of phase stresses were derived by Hooke's law on the basis of a simple method for the determination of stress-free lattice spacing in in situ composites. During compressive loading, the NiAl phase yields earlier than the Crss phase. The Crss phase carries much higher stress than the NiAl phase, and displays consistent strain hardening at all temperatures. The NiAl phase exhibits strain hardening at relatively low temperatures and softening at high temperatures. During unloading, the NiAl phase yields in tension whereas the Crss phase unloads elastically. Additionally, post-test microstructural observations show phase-through cracks at room temperature, micro cracks along phase interfaces at 600 °C and intact lamellae kinks at 800 °C, which is due to the increasing deformability of both phases as temperature rises.

  13. Temperature-dependent phase-specific deformation mechanisms in a directionally solidified NiAl-Cr(Mo) lamellar composite

    DOE PAGESBeta

    Yu, Dunji; An, Ke; Chen, Xu; Bei, Hongbin

    2015-10-09

    Phase-specific thermal expansion and mechanical deformation behaviors of a directionally solidified NiAl–Cr(Mo) lamellar in situ composite were investigated by using real-time in situ neutron diffraction during compression at elevated temperatures up to 800 °C. Tensile and compressive thermal residual stresses were found to exist in the NiAl phase and Crss (solid solution) phase, respectively. Then, based on the evolution of lattice spacings and phase stresses, the phase-specific deformation behavior was analyzed qualitatively and quantitatively. Moreover, estimates of phase stresses were derived by Hooke's law on the basis of a simple method for the determination of stress-free lattice spacing in inmore » situ composites. During compressive loading, the NiAl phase yields earlier than the Crss phase. The Crss phase carries much higher stress than the NiAl phase, and displays consistent strain hardening at all temperatures. The NiAl phase exhibits strain hardening at relatively low temperatures and softening at high temperatures. During unloading, the NiAl phase yields in tension whereas the Crss phase unloads elastically. Additionally, post-test microstructural observations show phase-through cracks at room temperature, micro cracks along phase interfaces at 600 °C and intact lamellae kinks at 800 °C, which is due to the increasing deformability of both phases as temperature rises.« less

  14. Elevated temperature creep-fatigue crack propagation in nickel-base alloys and 1 Cr-Mo-V steel

    NASA Astrophysics Data System (ADS)

    Nazmy, M.; Hoffelner, W.; Wüthrich, C.

    1988-04-01

    The crack growth behavior of several high temperature nickel-base alloys, under cyclic and static loading, is studied and reviewed. In the oxide dispersion strengthened (ODS) MA 6000 and MA 754 alloys, the high temperature crack propagation exhibited orientation dependence under cyclic as well as under static loading. The creep crack growth (CCG) behavior of cast nickel-base IN-738 and IN-939* superalloys at 850 °C could be characterized by the stress intensity factor, K 1. In the case of the alloy IN-901 at 500 °C and 600 °C, K 1 was found to be the relevant parameter to characterize the creep crack growth behavior. The energy rate line integral, C*, may be the appropriate loading parameter to describe the creep crack growth behavior of the nickel-iron base IN-800H alloy at 800 °C. The creep crack growth data of 1 Cr-Mo-V steel, with bainitic microstructure, at 550 °C could be correlated better by C * than by K 1.

  15. The effect of porous coating processing on the corrosion behavior of cast Co-Cr-Mo surgical implant alloys.

    PubMed

    Jacobs, J J; Latanision, R M; Rose, R M; Veeck, S J

    1990-11-01

    The manufacture of porous coated cobalt-based surgical implant alloys requires sintering--a high temperature process above the incipient melting temperature of this alloy system. The metallurgical changes produced by the high temperature sinter cycle consist of dissolution of interdendritic carbides, massive precipitation of lamellar carbide eutectic phases at grain boundaries, localized porosity from incipient melting that is not completely eliminated by subsequent hot isostatic pressing, and grain growth in fine-grained materials. These microstructural changes, which are known to affect the mechanical properties, do not affect the static in vitro localized and generalized corrosion behavior of the bulk material as determined by anodic polarization measurements in a buffered saline environment and direct examination by scanning electron and optical microscopy. Additionally, cast Co-Cr-Mo surgical implant alloys are found to be immune to crevice corrosion (in the absence of mechanical fretting) in the saline environment studied. The hysteretic component of the anodic polarization curve is not due to crevice corrosion; rather, as suggested by the electrochemical tests and Auger spectroscopy, the hysteresis is due to redox reactions in the chromium-rich surface layer. PMID:2213344

  16. Thermal stability and microstructural changes of some Ni-Cr-Mo alloys as detected by corrosion testing

    SciTech Connect

    Koehler, M.; Agarwal, D.C.

    1998-12-31

    Wrought Ni-Cr-Mo alloys of the C-family show a sensitivity to intercrystalline attack especially after exposure in the temperature range of 650 C to 950 C. Nevertheless, microstructural changes due to precipitation of intermetallic phases can occur up to a temperature level of 1050 C and this can affect the localized corrosion resistance. Thermal stability of wrought Alloy C-276 is a lot lower in comparison to Alloy 59. Sensitized at 870 C for only 1 hour, Alloy C-276 fails in the ASTM-G 28 B test due to rapid intercrystalline penetration and pitting whereas Alloy 59 can be aged up to 3 hours without any increase of the corrosion rate or any pitting attack. The same ranking applies during polythermal cooling cycles. Alloy C-276 requires a cooling rate of 150 C/min. between the solution annealing temperature and 600 C to avoid any sensitization whereas for Alloy 59 a relative slow cooling rate of 25 C/min. is acceptable. The critical pitting temperature of Alloy 59 when tested in the Green Death solution had been determined to be > 125 C. The temperature was not lowered during aging up to 3 hours at 1050 C or if a cooling speed of 25 C/min. was applied. However, cooling rates of 50 C/min. or less reduced the critical pitting temperature of Alloy C-276 from 115 C in the solution annealed and water quenched condition to only 105 C.

  17. Does surface wettability influence the friction and wear of large-diameter CoCrMo alloy hip resurfacings?

    PubMed

    Curran, Sarah; Hoskin, Tom; Williams, Sarah; Scholes, Susan C; Kinbrum, Amy; Unsworth, Anthony

    2013-08-01

    The role of surface tension in the lubrication of metal-on-metal (CoCrMo alloy) hip resurfacings has been investigated to try to explain why all metal joints fail to be lubricated with simple water-based lubricants (sodium carboxymethyl cellulose), which have similar rheology to synovial fluid, but are lubricated with the same fluid with the addition of a proportion of bovine serum. As part of this study, surfactants, in the form of detergents, when added to carboxymethyl cellulose, have been shown to produce a predominantly fluid-film lubrication mechanism with friction even lower than the biological lubricant containing serum. Friction factors were reduced by 80% when a detergent was added to the lubricant. It is considered that the failure of the water-based fluids to generate fluid-film lubrication is due to the fact that 'boundary slip' takes place where the fluid does not fully attach to the bounding solid surfaces as assumed in Reynolds' equation, thereby drawing in less lubricant than predicted from hydrodynamic theory. The addition of surfactants either in the form of natural materials such as serum or in the form of detergent reduces surface tension and helps the water-based lubricant to attach more fully to the bounding surfaces resulting in more fluid entrainment and thicker fluid-film formation. This was confirmed by up to 70% lower wear being found when these joints were lubricated in a detergent solution rather than 25% bovine serum.

  18. Does surface wettability influence the friction and wear of large-diameter CoCrMo alloy hip resurfacings?

    PubMed

    Curran, Sarah; Hoskin, Tom; Williams, Sarah; Scholes, Susan C; Kinbrum, Amy; Unsworth, Anthony

    2013-08-01

    The role of surface tension in the lubrication of metal-on-metal (CoCrMo alloy) hip resurfacings has been investigated to try to explain why all metal joints fail to be lubricated with simple water-based lubricants (sodium carboxymethyl cellulose), which have similar rheology to synovial fluid, but are lubricated with the same fluid with the addition of a proportion of bovine serum. As part of this study, surfactants, in the form of detergents, when added to carboxymethyl cellulose, have been shown to produce a predominantly fluid-film lubrication mechanism with friction even lower than the biological lubricant containing serum. Friction factors were reduced by 80% when a detergent was added to the lubricant. It is considered that the failure of the water-based fluids to generate fluid-film lubrication is due to the fact that 'boundary slip' takes place where the fluid does not fully attach to the bounding solid surfaces as assumed in Reynolds' equation, thereby drawing in less lubricant than predicted from hydrodynamic theory. The addition of surfactants either in the form of natural materials such as serum or in the form of detergent reduces surface tension and helps the water-based lubricant to attach more fully to the bounding surfaces resulting in more fluid entrainment and thicker fluid-film formation. This was confirmed by up to 70% lower wear being found when these joints were lubricated in a detergent solution rather than 25% bovine serum. PMID:23852389

  19. Autophagy mediated CoCrMo particle-induced peri-implant osteolysis by promoting osteoblast apoptosis.

    PubMed

    Wang, Zhenheng; Liu, Naicheng; Liu, Kang; Zhou, Gang; Gan, Jingjing; Wang, Zhenzhen; Shi, Tongguo; He, Wei; Wang, Lintao; Guo, Ting; Bao, Nirong; Wang, Rui; Huang, Zhen; Chen, Jiangning; Dong, Lei; Zhao, Jianning; Zhang, Junfeng

    2015-01-01

    Wear particle-induced osteolysis is the leading cause of aseptic loosening, which is the most common reason for THA (total hip arthroplasty) failure and revision surgery. Although existing studies suggest that osteoblast apoptosis induced by wear debris is involved in aseptic loosening, the underlying mechanism linking wear particles to osteoblast apoptosis remains almost totally unknown. In the present study, we investigated the effect of autophagy on osteoblast apoptosis induced by CoCrMo metal particles (CoPs) in vitro and in a calvarial resorption animal model. Our study demonstrated that CoPs stimulated autophagy in osteoblasts and PIO (particle-induced osteolysis) animal models. Both autophagy inhibitor 3-MA (3-methyladenine) and siRNA of Atg5 could dramatically reduce CoPs-induced apoptosis in osteoblasts. Further, inhibition of autophagy with 3-MA ameliorated the severity of osteolysis in PIO animal models. Moreover, 3-MA also prevented osteoblast apoptosis in an antiautophagic way when tested in PIO model. Collectively, these results suggest that autophagy plays a key role in CoPs-induced osteolysis and that targeting autophagy-related pathways may represent a potential therapeutic approach for treating particle-induced peri-implant osteolysis.

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

    SciTech Connect

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

    2008-07-24

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

  1. Life Assessment for Cr-Mo Steel Dissimilar Joints by Various Filler Metals Using Accelerated Creep Testing

    NASA Astrophysics Data System (ADS)

    Pan, Lei; Liu, Kun; Breton, Francis; -Grant Chen, X.

    2016-10-01

    Accelerated creep rupture tests were performed on T22/T91 dissimilar metal joints to determine the fracture location and rupture time of different weldments. Four configurations of deposited filler metal were tested using gas tungsten arc welding to estimate the service life for Cr-Mo steel dissimilar joints at elevated temperatures in power plants. Results indicated that failure in all configurations occurred in the tempered original microstructure and tempered austenite transformation products (martensite or bainite structure) as type IV cracking at the intercritical area of the heat-affected zone (ICHAZ) for both T22 and T91 sides rather than as a consequence of the different filler metals. Creep damage occurred with the formation of precipitations and microvoids. The correlation between applied stress and the Larson-Miller parameter (PLM) was determined to predict the service life of each material configuration. Calculated time-to-failure based on the PLM and test results for both temperature and applied stress parameters gave a reasonable fit. The dissimilar joints exhibited lower creep rupture compared to the base material indicating creep degradation of the weldment.

  2. Tearing Resistance Properties of Cr-Mo Steels with Internal Hydrogen Determined by the Potential Drop Method

    NASA Astrophysics Data System (ADS)

    Konosu, Shinji; Shimazu, Hidenori; Fukuda, Ryohei

    2015-12-01

    The tearing resistance, dJ/da, of conventional 2.25Cr-1Mo steels and a V-bearing steel (2.25Cr-1Mo-0.3V steel) with internal hydrogen was measured using the effective offset potential drop method. Internal hydrogen refers to test specimens that are precharged (thermally charged) prior to testing. In general, Cr-Mo steels, used widely in the refining and petrochemical industries, are susceptible to temper embrittlement. However, very few studies have dealt with the effects of hydrogen and temper embrittlement on the tearing resistance. Test specimens were prepared by subjecting them to normalizing, tempering, and post-weld heat treatments that simulated actual conditions. Some specimens were embrittled by step cooling. Hydrogen substantially reduced dJ/da for all samples except for that for the V-bearing steel, and temper embrittlement caused additional adverse effects on dJ/da for samples with internal hydrogen for which the temper embrittlement parameter, i.e., the J-factor, was large.

  3. Nd:YAG laser cladding of Co-Cr-Mo alloy on γ-TiAl substrate

    NASA Astrophysics Data System (ADS)

    Barekat, Masoud; Shoja Razavi, Reza; Ghasemi, Ali

    2016-06-01

    In this work, Co-Cr-Mo powder is used to form laser clads on a γ-TiAl substrate. The single-track geometrical characteristics such as width, height, penetration depth, dilution and wetting angle play the important role to control the characteristics of laser clad coatings formed by overlap of individual tracks. This paper is investigated the relations between the main coaxial laser cladding parameters (laser power P, laser beam scanning speed S and powder feeding rate F) and geometrical characteristics of single tracks by linear regression analysis. The results show that the clad height, H, depends linearly on the FS-5/4 parameter with the laser power having a minimal effect. Similarly, the cladding width W is controlled by the PS-2/3 parameter. The penetration depth b and dilution, D are proportional to P2S-1/4F-1/4 and P2/3S1/2F-1/2 respectively and wetting angle is controlled by the P1/4S1/2F-1/2 parameter. These empirical dependencies are observed with high values of the correlation coefficient (R>0.9). Finally, based on these relations, a laser cladd processing map was designed to use as a guideline for the selection of proper processing parameters for a required coating.

  4. High temperature passive film on the surface of Co-Cr-Mo alloy and its tribological properties

    NASA Astrophysics Data System (ADS)

    Guo, Feifei; Dong, Guangneng; Dong, Lishe

    2014-09-01

    For the artificial hip joints, passive film formed on the Co-Cr-Mo alloy acted as a highly protective barrier in the body fluid. But its stability, composition and structure always influenced the protection. In this work, passive film was obtained by high temperature treatment. The effect of passivation environment on the properties of the passive film was investigated. The film's surface roughness, micro-hardness and structure were analyzed. In order to study the tribological behavior of the passive film, pin-on-disk tribotest was carried out under bovine serum albumin (BSA) and saline solution. Results indicated the sample passivated in vacuum had friction coefficient of 0.18 under BSA solution and 0.53 under saline solution; the sample passivated in air had friction coefficient of 0.14 under BSA solution and 0.56 under saline solution. In addition, the reference sample without passivation was tested under the same condition. It showed friction of 0.22 under BSA solution and 0.45 under solution. The lubricating mechanism was attributed to BSA tribo-film absorption on the surface and high hardness passive film.

  5. Autophagy mediated CoCrMo particle-induced peri-implant osteolysis by promoting osteoblast apoptosis

    PubMed Central

    Wang, Zhenheng; Liu, Naicheng; Liu, Kang; Zhou, Gang; Gan, Jingjing; Wang, Zhenzhen; Shi, Tongguo; He, Wei; Wang, Lintao; Guo, Ting; Bao, Nirong; Wang, Rui; Huang, Zhen; Chen, Jiangning; Dong, Lei; Zhao, Jianning; Zhang, Junfeng

    2015-01-01

    Wear particle-induced osteolysis is the leading cause of aseptic loosening, which is the most common reason for THA (total hip arthroplasty) failure and revision surgery. Although existing studies suggest that osteoblast apoptosis induced by wear debris is involved in aseptic loosening, the underlying mechanism linking wear particles to osteoblast apoptosis remains almost totally unknown. In the present study, we investigated the effect of autophagy on osteoblast apoptosis induced by CoCrMo metal particles (CoPs) in vitro and in a calvarial resorption animal model. Our study demonstrated that CoPs stimulated autophagy in osteoblasts and PIO (particle-induced osteolysis) animal models. Both autophagy inhibitor 3-MA (3-methyladenine) and siRNA of Atg5 could dramatically reduce CoPs-induced apoptosis in osteoblasts. Further, inhibition of autophagy with 3-MA ameliorated the severity of osteolysis in PIO animal models. Moreover, 3-MA also prevented osteoblast apoptosis in an antiautophagic way when tested in PIO model. Collectively, these results suggest that autophagy plays a key role in CoPs-induced osteolysis and that targeting autophagy-related pathways may represent a potential therapeutic approach for treating particle-induced peri-implant osteolysis. PMID:26566231

  6. Characterization of precipitates in X12CrMoWVNbN10-1-1 steel during heat treatment

    NASA Astrophysics Data System (ADS)

    Tao, Xingang; Gu, Jianfeng; Han, Lizhan

    2014-09-01

    The characterization of precipitates in X12CrMoWVNbN10-1-1 steel during the heat treatment was carried out for revealing the evolution of the precipitates. In addition to other microstructural parameters (such as dislocation and subgrains), the precipitate also plays an important role for microstructural stability which is a prerequisite for long term creep strength. In this paper, the precipitates during the heat treatment for this steel were characterized using physicochemical phase analyses and transmission electron microscopy. It was found that the Fe-rich M3C carbides and Nb-rich MX particles were detected in the samples cooled in furnace from austenitization at 1080 °C for 16 h. However, after water cooling, only Nb-rich MX particles existed. During tempering at 570 °C for 18 h, the formation of Cr-rich M7C3 was detected but was replaced partially by Cr-rich M23C6. Additional Cr-rich M2N nitride was also found. After two successive tempering (570 °C + 690 °C) for 24 h, Cr-rich M7C3 was completely replaced. The microchemical analyses of the extracted residues during heat treatment were also discussed. The results gave rise to an indication that the precipitation of precipitates nearly completed in first tempering and the transformation from Cr-rich M7C3 to Cr-rich M23C6 mainly occurred in the second tempering.

  7. Reduced Pressure Electron Beam Welding Evaluation Activities on a Ni-Cr-Mo Alloy for Nuclear Waste Packages

    SciTech Connect

    Wong, F; Punshon, C; Dorsch, T; Fielding, P; Richard, D; Yang, N; Hill, M; DeWald, A; Rebak, R; Day, S; Wong, L; Torres, S; McGregor, M; Hackel, L; Chen, H-L; Rankin, J

    2003-09-11

    The current waste package design for the proposed repository at Yucca Mountain Nevada, USA, employs gas tungsten arc welding (GTAW) in fabricating the waste packages. While GTAW is widely used in industry for many applications, it requires multiple weld passes. By comparison, single-pass welding methods inherently use lower heat input than multi-pass welding methods which results in lower levels of weld distortion and also narrower regions of residual stresses at the weld TWI Ltd. has developed a Reduced Pressure Electron Beam (RPEB) welding process which allows EB welding in a reduced pressure environment ({le} 1 mbar). As it is a single-pass welding technique, use of RPEB welding could (1) achieve a comparable or better materials performance and (2) lead to potential cost savings in the waste package manufacturing as compared to GTAW. Results will be presented on the initial evaluation of the RPEB welding on a Ni-Cr-Mo alloy (a candidate alloy for the Yucca Mountain waste packages) in the areas of (a) design and manufacturing simplifications, (b) material performance and (c) weld reliability.

  8. Designing components for water treatment units for radioactive waste liquids in a modern NiCrMo-alloy

    SciTech Connect

    Kirchheiner, R.; Solomon, R.; Jahudka, M.; Ettere, J.

    1998-12-31

    Since the late 60`s, a uranium mine in eastern Europe (DIAMO) has used the In-Situ Leaching (ISL) method along with traditional underground mining. Over the years the acid solutions and leaching products have spread into a large volume of underground water and it is necessary to clean up this contaminated water. The make-up-process for the water purification requires highly alloyed materials for the equipment. In 1994 the operator awarded a US company a contract to clean up the acidic solutions and to produce a pure salt product using a system of evaporators, crystallizers and recrystallizers. In an attempt to simulate real plant conditions, test procedures were set up with the original mother liquor and its concentrate solution to qualify the optimum alloy for the given components. A NiCrMo-alloy (Alloy 31) was specified as part of the evaporator body on the Basis of corrosion and cost aspects. It has been reported that there is no visible appearance of corrosion on any part of equipment which has been fabricated from Alloy 31.

  9. Synthèse et étude structurale de Na9Cr(MoO4)6

    PubMed Central

    Dridi, Wassim; Ennajeh, Ines; Zid, Mohamed Faouzi

    2015-01-01

    The title compound, nona­sodium chromium(III) hexa­kis[molybdate(VI)], Na9Cr(MoO4)6 was prepared by solid-state reactions. The basic structure units are isolated polyhedral clusters composed of a central CrO6 octa­hedron sharing vertices with six MoO4 tetrahedra to form an open framework in which the Na+ cations are bound to the free vertices of the MoO4 tetra­hedra. The Cr3+ cation has site symmetry of 32 (6a), one Na atom sits on a twofold axis (18e), and all other atoms are at general positions. The bond-valance-sum model confirms the expected values of ion charges. The title compound is isotypic with Na9Sc(MoO4)6 and Na9Fe(MoO4)6. It is compared and discussed with similar structures. PMID:25995849

  10. Iron-base superalloys - A phase analysis of the multicomponent system (Fe-Mn-Cr-Mo-Nb-Al-Si-C)

    NASA Technical Reports Server (NTRS)

    Gupta, H.; Nowotny, H.; Lemkey, F. D.

    1988-01-01

    In the course of studies on the iron-rich multicomponent system Fe-Mn-Cr-Mo-Nb-Al-Si-C, work was concentrated on pertinent quinary and six-component combinations namely Fe-Mn-Al-Si-C, Fe-Cr-Al-Si-C and Fe-Mn-Cr-Al-Si-C which had been elaborated at 65, 72, and 80 wt pct Fe. Manganese acts as a strong stabilizer for the cementite carbide. Chromium seems to stabilize the iron aluminide Fe2Al5 which forms in a considerable amount within an alloy of nominal composition Fe(65)Mn(15)Cr(12)Al(5)Si(2)C(1) (percent by weight). Although the Mn3AlC carbide is, like Fe3AlC, a perovskite carbide, manganese does not appear to favor the formation of the perovskite carbide. Because of the relatively low sintering temperature (700 C), for al large portion of the samples equilibria conditions are not always reached.

  11. Restoration of Obliterated Numbers on 40NiCrMo4 Steel by Etching Method: Metallurgical and Statistical Approaches.

    PubMed

    Fortini, Annalisa; Merlin, Mattia; Soffritti, Chiara; Garagnani, Gian L

    2016-01-01

    The restoration of obliterated serial numbers is a problem of common occurrence in the forensic field. Among several restoration techniques, chemical etching is the most frequently used. The present research is aimed at studying the restoration of serial numbers, stamped on 40NiCrMo4 steel plates, by means of chemical etching. Microstructural characterization was firstly carried out to study the plastically deformed regions surrounding the marks. The obliteration was performed by controlled removals of material at increasing depths of erasure, and five etching reagents were considered to analyze their sensitivity and effectiveness. Experimental results revealed that Fry's reagent was the most sensitive, able to restore erased marks up to 60 μm under the depth of the imprint. The reagent comprising 25 mL HNO3 and 75 mL H2O provided good results, recovering the major numbers of characters. A descriptive statistical analysis was conducted to study the operator's influence on the recovered marks' identification.

  12. Increased osteoblast adhesion on nanophase metals: Ti, Ti6Al4V, and CoCrMo.

    PubMed

    Webster, Thomas J; Ejiofor, Jeremiah U

    2004-08-01

    Previous studies have demonstrated increased functions of osteoblasts (bone-forming cells) on nanophase compared to conventional ceramics (specifically, alumina, titania, and hydroxyapatite), polymers (such as poly lactic-glycolic acid and polyurethane), carbon nanofibers/nanotubes, and composites thereof. Nanophase materials are unique materials that simulate dimensions of constituent components of bone since they possess particle or grain sizes less than 100 nm. However, to date, interactions of osteoblasts on nanophase compared to conventional metals remain to be elucidated. For this reason, the objective of the present in vitro study was to synthesize, characterize, and evaluate osteoblast adhesion on nanophase metals (specifically, Ti, Ti6Al4V, and CoCrMo alloys). Such metals in conventional form are widely used in orthopedic applications. Results of this study provided the first evidence of increased osteoblast adhesion on nanophase compared to conventional metals. Interestingly, osteoblast adhesion occurred preferentially at surface particle boundaries for both nanophase and conventional metals. Since more particle boundaries are present on the surface of nanophase compared to conventional metals, this may be an explanation for the measured increased osteoblast adhesion. Lastly, material characterization studies revealed that nanometal surfaces possessed similar chemistry and only altered in degree of nanometer surface roughness when compared to their respective conventional counterparts. Because osteoblast adhesion is a necessary prerequisite for subsequent functions (such as deposition of calcium-containing mineral), the present study suggests that nanophase metals should be further considered for orthopedic implant applications.

  13. IBA analysis and corrosion resistance of TiAlPtN/TiAlN/TiAl multilayer films deposited over a CoCrMo using magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Canto, C. E.; Andrade, E.; de Lucio, O.; Cruz, J.; Solís, C.; Rocha, M. F.; Alemón, B.; Flores, M.; Huegel, J. C.

    2016-03-01

    The corrosion resistance and the elemental profile of multilayer coatings of TiAlPtN/TiAlN/TiAl synthesized by Physical Vapor Deposition (PVD) reactive magnetron sputtering over a CoCrMo alloy substrate in 10 periods of 30 min each were analyzed and compared to those of the substrate alone and to that of a TiAlPtN single layer coating of the same thickness. The objective of the present work was to create multilayers with different amounts of Pt to enhance the corrosion resistance of a biomedical alloy of CoCrMo. Corrosion tests were performed using Simulated Body Fluid (SBF) using potentiodynamic polarization tests at typical body temperature. The elemental composition and thickness of the coatings were evaluated with the combination of two ion beam analysis (IBA) techniques: a Rutherford Backscattering Spectroscopy (RBS) with alpha beam and a Nuclear Reaction Analysis with a deuteron beam.

  14. Comparative Study on the Corrosion Resistance of Fe-Based Amorphous Metal, Borated Stainless Steel and Ni-Cr-Mo-Gd Alloy

    SciTech Connect

    Lian, Tiangan; Day, Daniel; Hailey, Phillip; Choi, Jor-Shan; Farmer, Joseph

    2007-07-01

    Iron-based amorphous alloy Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} was compared to borated stainless steel and Ni-Cr-Mo-Gd alloy on their corrosion resistance in various high-concentration chloride solutions. The melt-spun ribbon of this iron-based amorphous alloy have demonstrated a better corrosion resistance than the bulk borated stainless steel and the bulk Ni-Cr-Mo-Gd alloy, in high-concentration chloride brines at temperatures 90 deg. C or higher. (authors)

  15. Generation of the periodic surface structures on the dental Co-Cr-Mo alloy by Nd:YAG laser in an inert atmosphere

    NASA Astrophysics Data System (ADS)

    Vasylyev, M. A.; Tinkov, V. A.; Filatova, V. S.; Voloshko, S. M.; Gurin, P. A.

    2012-03-01

    The influence of the impulse laser irradiation (Nd:YAG laser λ = 1.06 μm) in an inert atmosphere (Ar) with different power density on the surface morphology of the dental Co-Cr-Mo alloy surface was studied. It is set that periodic ring relief appears at the modes of the treatment with melting and evaporation of the material. The analysis of the periodic structure main characteristics was performed.

  16. Effects of helium content of microstructural development in Type 316 stainless steel under neutron irradiation

    SciTech Connect

    Maziasz, P.J.

    1985-11-01

    This work investigated the sensitivity of microstructural evolution, particularly precipitate development, to increased helium content during thermal aging and during neutron irradiation. Helium (110 at. ppM) was cold preinjected into solution annealed (SA) DO-heat type 316 stainess steel (316) via cyclotron irradiation. These specimens were then exposed side by side with uninjected samples. Continuous helium generation was increased considerably relative to EBR-II irradiation by irradiation in HFIR. Data were obtained from quantitative analytical electron microscopy (AEM) in thin foils and on extraction replicas. 480 refs., 86 figs., 19 tabs.

  17. Effects of neutron irradiation of ultra-thin HfO{sub 2} films

    SciTech Connect

    Hsu, K.-W.; Bian, S.; Shohet, J. L.; Ren, H.; Agasie, R. J.; Nishi, Y.

    2014-01-20

    Neutron irradiation at low fluence decreases the Pb-type and E′ defect levels in ultra-thin hafnium dioxide films because electrons can fill existing states. These electrons come from electron-hole pairs generated by neutron interactions with silicon and oxygen. Thus, a low fluence of neutrons “anneals” the sample. However, when neutron fluence increases, more neutrons collide with oxygen atoms and cause them to leave the lattice or to transmute into different atoms. This causes the E′ states to increase. As defect-state concentrations increase, leakage currents increase, but since the E′ is much lower than the Pb concentration, this is not a dominant factor.

  18. Extraction of protactinium-233 and separation from thermal neutron-irradiated thorium-232 using crown ethers

    SciTech Connect

    Jalhoom, Moayyed G.; Mohammed, Dawood A.; Khalaf, Jumah S.

    2008-07-01

    A new method was developed for the extraction and separation of {sup 233}Pa from thermal neutron-irradiated {sup 232}Th. Solutions of Pa{sup 233} were prepared in LiCI-HCl solutions from which appreciable extraction was obtained using dibenzo-18-crown-6 in 1,2-dichloroethane. The effects of cavity size, substitutions on the crown ring, type of the organic solvent, and temperature on extraction are discussed. Very high separation factors were obtained for the pairs {sup 233}Pa/{sup 232}Th (>105), {sup 233}Pa/{sup 233}U (> 1000), and {sup 232}U/{sup 232}Th (>60). (authors)

  19. Uses of AES and RGA to study neutron-irradiation-enhanced segregation to internal surfaces

    SciTech Connect

    Gessel, G.R.; White, C.L.

    1980-01-01

    The high flux of point defects to sinks during neutron irradiation can result in segregation of impurity or alloy additions to metals. Such segregants can be preexisting or produced by neutron-induced transmutations. This segregation is known to strongly influence swelling and mechanical properties. Over a period of years, facilities have been developed at ORNL incorporating AES and RGA to examine irradiated materials. Capabilities of this system include in situ tensile fracture at elevated temperatures under ultrahigh vacuum 10/sup -10/ torr and helium release monitoring. AES and normal incidence inert ion sputtering are exploited to examine segregation at the fracture surface and chemical gradients near the surface.

  20. Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

    SciTech Connect

    Masashi Shimada; M. Hara; T. Otsuka; Y. Oya; Y. Hatano

    2014-05-01

    Accurately estimating tritium retention in plasma facing components (PFCs) and minimizing its uncertainty are key safety issues for licensing future fusion power reactors. D-T fusion reactions produce 14.1 MeV neutrons that activate PFCs and create radiation defects throughout the bulk of the material of these components. Recent studies show that tritium migrates and is trapped in bulk (>> 10 µm) tungsten beyond the detection range of nuclear reaction analysis technique [1-2], and thermal desorption spectroscopy (TDS) technique becomes the only established diagnostic that can reveal hydrogen isotope behavior in in bulk (>> 10 µm) tungsten. Radiation damage and its recovery mechanisms in neutron-irradiated tungsten are still poorly understood, and neutron-irradiation data of tungsten is very limited. In this paper, systematic investigations with repeated plasma exposures and thermal desorption are performed to study defect annealing and thermal desorption of deuterium in low dose neutron-irradiated tungsten. Three tungsten samples (99.99 at. % purity from A.L.M.T. Co., Japan) irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to high flux (ion flux of (0.5-1.0)x1022 m-2s-1 and ion fluence of 1x1026 m-2) deuterium plasma at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy (TDS) was performed with a ramp rate of 10 °C/min up to 900 °C, and the samples were annealed at 900 °C for 0.5 hour. These procedures were repeated three (for 100 and 200 °C samples) and four (for 500 °C sample) times to uncover damage recovery mechanisms and its effects on deuterium behavior. The results show that deuterium retention decreases approximately 90, 75, and 66 % for 100, 200, and 500 °C, respectively after each annealing. When subjected to the same TDS recipe, the desorption temperature shifts from 800 °C to 600 °C after 1st annealing

  1. Low-temperature properties of neutron irradiated CuGeO3 single crystals

    NASA Astrophysics Data System (ADS)

    Gladczuk, L.; Mosiniewicz-Szablewska, E.; Dabkowska, H.; Baran, M.; Pytel, B.; Szymczak, R.; Szymczak, H.

    2000-07-01

    The effect of neutron irradiation on the magnetic properties of CuGeO3 single crystal which shows the spin-Peierls transition below T sp=14 K was investigated by means of electron paramagnetic resonance (EPR) and susceptibility measurements. It was found that the irradiation led to a decrease of the spin-Peierls transition temperature and induced appreciable changes in the EPR signal intensity, resonance linewidth, g-factor and magnetic susceptibility of this material. These changes may be associated with a partial suppression of both the energy gap and the dimerization within the Cu chains.

  2. Effect of neutron irradiation on fracture toughness behaviour of copper alloys

    NASA Astrophysics Data System (ADS)

    Tähtinen, S.; Pyykkönen, M.; Karjalainen-Roikonen, P.; Singh, B. N.; Toft, P.

    1998-10-01

    One of the most important factors in deciding about the applicability of materials in the structural components of ITER, is the effect of neutron irradiation on the fracture toughness behaviour of these materials. In the present work, the fracture toughness properties of two candidate materials for the first wall and divertor components of ITER, namely precipitation hardened CuCrZr and dispersion hardened CuAl25 alloys, have been studied in the unirradiated and irradiated conditions. In parallel, tensile properties of these alloys have been also investigated in the unirradiated and irradiated conditions.

  3. Defect-induced magnetism in neutron irradiated 6H-SiC single crystals.

    PubMed

    Liu, Yu; Wang, Gang; Wang, Shunchong; Yang, Jianhui; Chen, Liang; Qin, Xiubo; Song, Bo; Wang, Baoyi; Chen, Xiaolong

    2011-02-25

    Defect-induced magnetism is firstly observed in neutron irradiated SiC single crystals. We demonstrated that the intentionally created defects dominated by divacancies (V(Si)V(C)) are responsible for the observed magnetism. First-principles calculations revealed that defect states favor the formation of local moments and the extended tails of defect wave functions make long-range spin couplings possible. Our results confirm the existence of defect-induced magnetism, implying the possibility of tuning the magnetism of wide band-gap semiconductors by defect engineering.

  4. The observation of structural defects in neutron-irradiated lithium-doped silicon solar cells

    NASA Technical Reports Server (NTRS)

    Sargent, G. A.

    1971-01-01

    Electron microscopy has been used to observe the distribution and morphology of lattice defects introduced into lithium-doped silicon solar cells by neutron irradiation. Upon etching the surface of the solar cells after irradiation, crater-like defects are observed that are thought to be associated with the space charge region around vacancy clusters. Thermal annealing experiments showed that the crater defects were stable in the temperature range 300 to 1200 K in all of the lithium-doped samples. Some annealing of the crater defects was observed to occur in the undoped cells which were irradiated at the lowest doses.

  5. Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source

    SciTech Connect

    Andreani, C.; Pietropaolo, A.; Salsano, A.; Gorini, G.; Tardocchi, M.; Paccagnella, A.; Gerardin, S.; Frost, C. D.; Ansell, S.; Platt, S. P.

    2008-03-17

    The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10 MeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 10{sup 7}. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays.

  6. Development of ferritic steels for fusion reactor applications

    SciTech Connect

    Klueh, R.L.; Maziasz, P.J.; Corwin, W.R.

    1988-08-01

    Chromium-molybdenum ferritic (martensitic) steels are leading candidates for the structural components for future fusion reactors. However, irradiation of such steels in a fusion environment will produce long-lived radioactive isotopes that will lead to difficult waste-disposal problems. Such problems could be reduced by replacing the elements in the steels (i.e., Mo, Nb, Ni, N, and Cu) that lead to long-lived radioactive isotopes. We have proposed the development of ferritic steels analogous to conventional Cr-Mo steels, which contain molybdenum and niobium. It is proposed that molybdenum be replaced by tungsten and niobium be replaced by tantalum. Eight experimental steels were produced. Chromium concentrations of 2.25, 5, 9, and 12% were used (all concentrations are in wt %). Steels with these chromium compositions, each containing 2% W and 0.25% V, were produced. To determine the effect of tungsten and vanadium, 2.25 Cr steels were produced with 2% W and no vanadium and with 0.25% V and O and 1% W. A 9Cr steel containing 2% W, 0.25 V, and 0.07% Ta was also studied. For all alloys, carbon was maintained at 0.1%. Tempering studies on the normalized steels indicated that the tempering behavior of the new Cr-W steels was similar to that of the analogous Cr-Mo steels. Microscopy studies indicated that 2% tungsten was required in the 2.25 Cr steels to produce 100% bainite in 15.9-mm-thick plate during normalization. The 5Cr and 9Cr steels were 100% martensite, but the 12 Cr steel contained about 75% martensite with the balance delta-ferrite. 33 refs., 35 figs., 5 tabs.

  7. Effect of aqueous solution and load on the formation of DLC transfer layer against Co-Cr-Mo for joint prosthesis.

    PubMed

    Guo, Feifei; Zhou, Zhifeng; Hua, Meng; Dong, Guangneng

    2015-09-01

    Diamond-like carbon (DLC) coating exhibits excellent mechanical properties such as high hardness, low friction and wear, which offer a promising solution for the metal-on-metal hip joint implants. In the study, the hydrogen-free DLC coating with the element Cr as the interlay addition was deposited on the surface of the Co-Cr-Mo alloy by a unbalanced magnetron sputtering method. The coating thickness was controlled as 2 µm. Nano-indentation test indicated the hardness was about 13 GPa. DLC coated Co-Cr-Mo alloy disc against un-coated Co-Cr-Mo alloy pin (spherical end SR9.5) comprised the friction pairs in the pin-on-disc tribotest under bovine serum albumin solution (BSA) and physiological saline(PS).The tribological behavior under different BSA concetrations(2-20 mg/ml), and applied load (2-15N) was investigated.DLC transfer layer did not form under BSA solution, even though different BSA concetration and applied load changed. The coefficient of friction(COF) under 6 mg/ml BSA at 10 N was the lowest as 0.10. A higher COF of 0.13 was obtained under 20 mg/ml BSA. The boundary absorption layer of protein is the main factor for the counterparts. However, the continous DLC transfer layer was observed under PS solution, which make a lower COF of 0.08.

  8. Evaluation of thermal neutron irradiation field using a cyclotron-based neutron source for alpha autoradiography.

    PubMed

    Tanaka, H; Sakurai, Y; Suzuki, M; Masunaga, S; Mitsumoto, T; Kinashi, Y; Kondo, N; Narabayashi, M; Nakagawa, Y; Watanabe, T; Fujimoto, N; Maruhashi, A; Ono, K

    2014-06-01

    It is important to measure the microdistribution of (10)B in a cell to predict the cell-killing effect of new boron compounds in the field of boron neutron capture therapy. Alpha autoradiography has generally been used to detect the microdistribution of (10)B in a cell. Although it has been performed using a reactor-based neutron source, the realization of an accelerator-based thermal neutron irradiation field is anticipated because of its easy installation at any location and stable operation. Therefore, we propose a method using a cyclotron-based epithermal neutron source in combination with a water phantom to produce a thermal neutron irradiation field for alpha autoradiography. This system can supply a uniform thermal neutron field with an intensity of 1.7×10(9) (cm(-2)s(-1)) and an area of 40mm in diameter. In this paper, we give an overview of our proposed system and describe a demonstration test using a mouse liver sample injected with 500mg/kg of boronophenyl-alanine.

  9. Subtask 12F3: Effects of neutron irradiation on tensile properties of vanadium-base alloys

    SciTech Connect

    Loomis, B.A.; Chung, H.M.; Smith, D.L.

    1995-03-01

    The objective of this work is to determine the effects of neutron irradiation on the tensile properties of candidate vanadium-base alloys. Vanadium-base alloys of the V-Cr-Ti system are attractive candidates for use as structural materials in fusion reactors. The current focus of the U.S. program of research on these alloys is on the V-(4-6)Cr-(3-6)Ti-(0.05-0.1)Si (in wt.%) alloys. In this paper, we present experimental results on the effects of neutron irradiation on tensile properties of selected candidate alloys after irradiation at 400{degrees}C-600{degrees}C in lithium in fast fission reactors to displacement damages of up to {approx}120 displacement per atom (dpa). Effects of irradiation temperature and dose on yield and ultimate tensile strengths and uniform and total elongations are given for tensile test temperatures of 25{degrees}C, 420{degrees}C, 500{degrees}, and 600{degrees}C. Effects of neutron damage on tensile properties of the U.S. reference alloy V-4Cr-4Ti are examined in detail. 7 refs., 10 figs., 1 tab.

  10. The effect of neutron irradiation dose on vacancy defect accumulation and annealing in pure nickel

    NASA Astrophysics Data System (ADS)

    Druzhkov, A. P.; Arbuzov, V. L.; Perminov, D. A.

    2012-02-01

    In order to investigate the dose dependence of vacancy defect evolution in nickel, specimens of high-purity Ni were neutron-irradiated at ˜330 K in the IVV-2M reactor (Russia) to fluencies in the range of 1 × 10 21-1 × 10 23 n/m 2 ( E > 0.1 MeV) corresponding to displacement dose levels in the range of about 0.0001-0.01 dpa and subsequently stepwise annealed to about 900 K. Ni was characterized both in as-irradiated state as well as after post-irradiation annealing by positron annihilation spectroscopy. The formation of three-dimensional vacancy clusters (3D-VCs) in cascades was observed under neutron irradiation, the concentration of 3D-VCs increases with increasing dose level. 3D-VCs collapse into secondary-type clusters (stacking fault tetrahedra (SFTs), and vacancy loops) during stepwise annealing at 350-450 K. It is shown that the thermal stability of SFTs grow with increasing dose level, probably, it is due to growth of the average SFT size during annealing. The results of annealing experiments on electron-irradiated Ni at 300 K are indicated in the paper, for comparison. We also have briefly discussed the positron response to the SFT-like structures.

  11. The response of ataxia-telangiectasia lymphoblastoid cells to neutron irradiation

    SciTech Connect

    Houldsworth, J.; Cohen, D.; Singh, S.; Lavin, M.F. )

    1991-03-01

    The response of control and ataxia-telangiectasia (A-T) cells to increasing doses of high-linear-energy-transfer (LET) ionizing radiation (neutrons) was compared. Ataxia-telangiectasia cells were markedly more sensitive to neutron irradiation than were control cells. The D0 value for the two A-T cell lines was 0.4 Gy while the value for controls was approximately 1.4 Gy. Fast neutrons were considerably more effective than gamma rays in inducing cell death in both cell types, but the sensitivity factor remained approximately the same as with gamma rays. A minimal depression of DNA synthesis was observed in ataxia-telangiectasia cells after neutron irradiation, similar to that reported previously after gamma irradiation. The extent of inhibition was not significantly greater in control cells, contrary to that seen with gamma rays. In time-course experiments a significant difference in degree of inhibition of DNA synthesis was observed between the cell types. Low doses of fast neutrons induced a G2-phase delay in both cell types, but the degree and extent of this delay was greater in ataxia-telangiectasia cells as observed previously with low-LET radiation.

  12. Energy spectra of primary knock-on atoms under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Gilbert, M. R.; Marian, J.; Sublet, J.-Ch.

    2015-12-01

    Materials subjected to neutron irradiation will suffer from a build-up of damage caused by the displacement cascades initiated by nuclear reactions. Previously, the main "measure" of this damage accumulation has been through the displacements per atom (dpa) index, which has known limitations. This paper describes a rigorous methodology to calculate the primary atomic recoil events (often called the primary knock-on atoms or PKAs) that lead to cascade damage events as a function of energy and recoiling species. A new processing code SPECTRA-PKA combines a neutron irradiation spectrum with nuclear recoil data obtained from the latest nuclear data libraries to produce PKA spectra for any material composition. Via examples of fusion relevant materials, it is shown that these PKA spectra can be complex, involving many different recoiling species, potentially differing in both proton and neutron number from the original target nuclei, including high energy recoils of light emitted particles such as α-particles and protons. The variations in PKA spectra as a function of time, neutron field, and material are explored. The application of PKA spectra to the quantification of radiation damage is exemplified using two approaches: the binary collision approximation and stochastic cluster dynamics, and the results from these different models are discussed and compared.

  13. The effect of alloying elements on the defect structural evolution in neutron irradiated Ni alloys

    NASA Astrophysics Data System (ADS)

    Yoshiie, T.; Xu, Q.; Satoh, Y.; Ohkubo, H.; Kiritani, M.

    2000-12-01

    The effect of alloying elements, Si (-5.8%: the volume size factor in Ni), Ge (+14.76%) and Sn (+74.08%), on void swelling in neutron irradiated Ni at 573 K was studied by transmission electron microscope (TEM) observation and positron annihilation lifetime measurement. Neutron irradiation dose was changed widely from 0.001 to 0.4 dpa using two reactors, the Kyoto University reactor (KUR) and the Japan materials testing reactor (JMTR). Voids were observed in pure Ni by TEM even after very small irradiation dose of 0.001 dpa. With increasing dose, the density of voids did not change much while their size increased. The same tendency was observed in Ni-2at.%Ge. In Ni-2at.%Sn and Ni-2at.%Si, however, no voids were observed by TEM at a damage dose of 0.4 dpa. But positron lifetime measurement revealed the existence of microvoids at a medium dose of irradiation. When irradiation dose increased to 0.4 dpa in Ni-2at.%Si and 0.13 dpa in Ni-2at.%Sn, their existence was not detected. Suppression of microvoids in these alloys is discussed from the standpoint of solute point defect interactions.

  14. Results of d+T fast neutron irradiation on advanced tumors of bladder and rectum

    SciTech Connect

    Battermann, J.J.

    1982-12-01

    From November, 1975 to November, 1981, around 400 patients were irradiated with 14 MeV d+T fast neutrons at the Antoni van Leeuwenhoek Hospital in Amsterdam. Special interest was focused on inoperable tumors of bladder and rectum. During the pilot phase of the study 47 patients were treated, mostly via two parallel opposed ports with dosages that ranged from 18 to more than 22 Gy. Although persistent local control was achieved in 23 patients (48%), 14 patients (29%) died of severe complications. By the introduction of a six field technique, the fatal complication rate could be reduced significantly. Since May 1978 patients were randomized in a three arm trial, using two dose levels on the neutron site. The preliminary results of a group of 91 patients show a similar survival in the three treatment arms with a somewhat better local control rate for high dose neutrons. An attempt was made to estimate RBE values for tumor control and normal tissue reactions by comparing the data for neutron irradiation with the data obtained with photons on a similar group of patients. From the values derived it must be concluded that the gain for neutron irradiation on these tumors in the pelvis will be negligible.

  15. Results of d+T fast neutron irradiation on advanced tumors of bladder and rectum

    SciTech Connect

    Battermann, J.J.

    1982-12-01

    From November, 1975 to November, 1981, around 400 patients were irradiated with 14 MeV d+T fast neutrons at the Antoni van Leeuwenhoek Hospital in Amsterdam. Special interest was focused on inoperable tumors of bladder and rectum. During the pilot phase of the study 47 patients were treated, mostly via two parallel opposed ports with dosages that ranged from 18 to more than 22 Gy. Although persistent local control was achieved in 23 patients (48%), 14 patients (29%) died of severe complications. By the introduction of a six field technique, the fatal complication rate could be reduced significantly. Since May 1978 patients were randomized in a three arm trial, using two dose levels on the neutron site. The preliminary results of a group of 91 patients show a similar survival in the three treatment arms with a somewhat better local control rate for high dose neutrons. An attempt was made to estimate RBE values for tumor control and normal tissue reaction by comparing the data for neutron irradiation with the data obtained with photons on a similar group of patients. From the values derived it must be concluded that the gain for neutron irradiation on these tumors in the pelvis will be negligible.

  16. Degradation of mechanical properties of stainless steel cladding due to neutron irradiation and thermal aging

    SciTech Connect

    Haggag, F.M.

    1994-09-01

    Thermal aging of three-wire series-arc stainless steel weld overlay cladding at 288{degrees}C for 1605 h resulted in an appreciable decrease (16%) in the Charpy V-notch (CVN) upper-shelf energy (USE), but the effect on the 41-J transition temperature shift was very small (3{degrees}C). The combined effect following neutron irradiation at 288{degrees}C to a fluence of 5 X 10{sup 19} neutrons/cm{sup 2} (>1 MeV) was a 22% reduction in the USE and a 29{degrees}C shift in the 41-J transition temperature. The effect of thermal aging on tensile properties was very small. However, the combined effect of irradiation and aging was an increase in the yield strength (6 to 34% at test temperatures from 288 to -125{degrees}C) and no apparent change in ultimate tensile strength or total elongation. Neutron irradiation reduced the initiation fracture toughness (J{sub {kappa}}) much more than did thermal aging alone. However, irradiation slightly decreased the tearing modulus but no reduction was caused by thermal aging alone. The effects of long-term thermal exposure times (20,000 and 50,000 h) will be investigated when the specimens become available. Also, long-term thermal exposure of the three-wire cladding as well as type 308 stainless steel weld materials at 343{degrees}C is in progress.

  17. The Effect of Neutron Irradiation on the Fracture Toughness of Graphite

    SciTech Connect

    Burchell, Timothy D; Strizak, Joe P

    2012-01-01

    As part of our irradiated graphite recycle program a small quantity of PCEA grade graphite was irradiated in the High Flux Isotope Reactor (HFIR) at ORNL. The graphite will provide the raw material for future recycle experiments. The geometry of the irradiated graphite allowed us to study the effects of neutron irradiation on the Critical Stress Intensity Factor, KIc, of graphite. The specimens where irradiated in two groups of 6 at an irradiation temperature of 900 C in rabbit capsules to doses of 6.6 and 10.2 DPA, respectively. Following a full suite of pre-and post-irradiation examination, which included dimensions, mass, electrical resistivity, elastic constants, and thermal expansion (to 800 C) the samples were notched and tested to determine their KIc using the newly approved ATSM test method for SENB fracture toughness of graphite. Here we report the irradiation induced changes in the dimensions, elastic constants, resistivity, and coefficient of thermal expansion of PCEA graphite. Moreover, irradiation induced changes in the Critical Stress Intensity Factor, KIc, or fracture toughness, are reported and discussed. Very little work on the effect of neutron irradiation on the fracture toughness of graphite has previously be performed or reported.

  18. Investigation of the combined effect of neutron irradiation and electron beam exposure on pure tungsten

    NASA Astrophysics Data System (ADS)

    Van Renterghem, W.; Uytdenhouwen, I.

    2016-08-01

    Pure tungsten samples were neutron irradiated in the BR2 reactor of SCK·CEN to fluences of 1.47 × 1020 n/cm2 and 4.74 × 1020 n/cm2 at 300 °C under Helium atmosphere and exposed to the electron beam of the Judith 1 installation The effect of these treatments on the defect structure was studied with transmission electron microscopy. In the irradiated samples the defect structure in the bulk is compared to the structure at the surface. The neutron irradiation created a large amount of a/2‹111› type dislocation loops forming dislocation rafts. The loop density increased from 8.5 × 1021/m³ to 9 × 1022/m³ with increasing dose, while the loop size decreased from 5.2 nm to 3.5 nm. The electron beam exposure induced significant annealing of the defects and almost all of the dislocation loops were removed. The number of line dislocations in that area increased as a result of the thermal stresses from the thermal shock.

  19. Neutron irradiation induced microstructural changes in NBG-18 and IG-110 nuclear graphites

    SciTech Connect

    Karthik, Chinnathambi; Kane, Joshua; Butt, Darryl P.; Windes, William E.; Ubic, Rick

    2015-05-01

    This paper reports the neutron-irradiation-induced effects on the microstructure of NBG-18 and IG-110 nuclear graphites. The high-temperature neutron irradiation at two different irradiation conditions was carried out at the Advanced Test Reactor National User Facility at the Idaho National Laboratory. NBG-18 samples were irradiated to 1.54 dpa and 6.78 dpa at 430 °C and 678 °C respectively. IG-110 samples were irradiated to 1.91 dpa and 6.70 dpa at 451 °C and 674 °C respectively. Bright-field transmission electron microscopy imaging was used to study the changes in different microstructural components such as filler particles, microcracks, binder and quinoline-insoluble (QI) particles. Significant changes have been observed in samples irradiated to about 6.7 dpa. The closing of pre-existing microcracks was observed in both the filler and the binder phases. The binder phase exhibited substantial densification with near complete elimination of the microcracks. The QI particles embedded in the binder phase exhibited a complete microstructural transformation from rosettes to highly crystalline solid spheres. The lattice images indicate the formation of edge dislocations as well as extended line defects bridging the adjacent basal planes. The positive climb of these dislocations has been identified as the main contributor to the irradiation-induced swelling of the graphite lattice.

  20. Neutron irradiation study of Nd-Fe-B permanent magnets made from melt-spun ribbons

    SciTech Connect

    Brown, R.D.; Cost, J.R.; Meisner, G.P.; Brewer, E.G.

    1988-01-01

    Radiation-induced changes in the magnetization of sintered Nd-Fe-B permanent magnets are known to vary widely among specimens produced by different manufacturers. Samples of Nd-Fe-B MAGNEQUENCH magnets, which are made from melt-spun ribbons, have now been studied and show a much reduced sensitivity to neutron irradiation than do sintered Nd-Fe-B magnets. All melt-spun ribbon-based MAGNEQUENCH magnets, i.e., epoxy-bonded, hot-pressed, and die-upset magnets, show essentially the same slow decrease in magnetic remanence with neutron dose. Measurements of the open-circuit remanence B/sub r//B/sub ro/ at various times during the irradiation show a decay of only 1.5% of the preirradiated value for the MAGNEQUENCH magnets after 1 hour of irradiation, or a dose of 1.4 /times/ 10/sup 16/ neutrons/cm/sup 2/, compared to a 4.6% drop in remanence for the best sintered Nd-Fe-B magnet (Sumitomo 3OH) with the same irradiation dose. Moreover, after 5.3 hours of irradiation, the remanence drops by only 3% for the MAGNEQUENCH magnets. Magnets made from melt-spun ribbons are thus the least sensitive to neutron irradiation so far measured for Nd-Fe-B permanent magnets, but are somewhat more sensitive than samarium-cobalt magnets. 12 refs., 1 fig.

  1. Development of microstructure and mechanical properties during annealing of a cold-swaged Co-Cr-Mo alloy rod.

    PubMed

    Mori, Manami; Sato, Nanae; Yamanaka, Kenta; Yoshida, Kazuo; Kuramoto, Koji; Chiba, Akihiko

    2016-12-01

    In this study, we investigated the evolution of the microstructure and mechanical properties during annealing of a cold-swaged Ni-free Co-Cr-Mo alloy for biomedical applications. A Co-28Cr-6Mo-0.14N-0.05C (mass%) alloy rod was processed by cold swaging, with a reduction in area of 27.7%, and then annealed at 1173-1423K for various periods up to 6h. The duplex microstructure of the cold-swaged rod consisted of a face-centered cubic γ-matrix and hexagonal closed-packed ε-martensite developed during cold swaging. This structure transformed nearly completely to the γ-phase after annealing and many annealing twin boundaries were observed as a result of the heat treatment. A small amount of the ε-phase was identified in specimens annealed at 1173K. Growth of the γ-grains occurred with increasing annealing time at temperatures ≥1273K. Interestingly, the grain sizes remained almost unchanged at 1173K and a very fine grain size of approximately 8μm was obtained. The precipitation that occurred during annealing was attributed to the limited grain coarsening during heat treatment. Consequently, the specimens treated at this temperature showed the highest tensile strength and lowest ductility among the specimens prepared. An elongation-to-failure value larger than 30% is sufficient for the proposed applications. The other specimens treated at higher temperatures possessed similar tensile properties and did not show any significant variations with different annealing times. Optimization of the present rod manufacturing process, including cold swaging and interval annealing heat treatment, is discussed. PMID:27500542

  2. The effect of contact load on CoCrMo wear and the formation and retention of tribofilms

    PubMed Central

    Wimmer, M.A.; Laurent, M.P.; Mathew, M.T.; Nagelli, C.; Liao, Y.; Marks, L.D.; Jacobs, J.J.; Fischer, A.

    2015-01-01

    Tribochemical reactions in a protein lubricated metal-on-metal (MoM) sliding contact may play a significant role for its wear performance. Such reactions lead to the formation of a carbonaceous ‘tribofilm’, which can act as a protective layer against corrosion and wear. The purpose of this study was to determine the effect of contact load on wear and the formation and retention of tribofilms. Wear tests were performed in a custom-made ball-on-flat testing apparatus that incorporated an electrochemical cell. A ceramic ball was used to articulate against low-carbon wrought CoCrMo alloy pins in bovine serum. Using a range of contact loads at a single potentiostatic condition (close to free potential), weight loss and changes in surface properties were evaluated. We determined that wear was influenced by the loading condition. As expected, wear increased with load, but the association between applied load and measured weight loss was not linear. In the intermediate load region, in the range of 32–48 N (~58–80 MPa), there was more than an order of magnitude drop in the wear per unit load, and the wear versus load data suggested an inflexion point at 49 N. Regression analyses yielded a cubic model (R2=0.991; p=0.0002), where the cubic term, which represents the inflexion, was highly significant (p=0.0021). This model is supported by the observations that the minimum in the friction versus load curve is at 52 N and the highest relative increase in polarization resistance occurred at 49 N. Scanning electron microscopy and Raman spectroscopy indicated the absence of a tribofilm for the low and within the contact area of the high load cases. Synergistic interactions of wear and corrosion seem to play an important role. PMID:26085697

  3. Evaluation of ferritic alloy Fe-2-1/4Cr-1Mo after neutron irradiation - microstructure development

    SciTech Connect

    Gelles, D.S.

    1984-05-01

    Microstructural examinations are reported for nine specimen conditions of 2-1/4Cr-1Mo steel which had been irradiated by fast neutrons over the temperature range 390 to 510/sup 0/C. Two heats of material were involved, each with a different preirradiation heat treatment, one irradiated to a peak fluence of 5.1 x 10/sup 22/ n/cm/sup 2/ (E > 0.1 MeV) or 24 dpa and the other to 2.4 x 10/sup 23/ n/cm/sup 2/ (E > 0.1 MeV) or 116 dpa. Void swelling is found following irradiation at 400/sup 0/C in both conditions and to 480/sup 0/C in the higher fluence conditions. Concurrently dislocation structure and precipitation formed. Peak void swelling, void density, dislocation density and precipitate number density developed at the lowest temperature, approx. 400/sup 0/C, whereas mean void size, and mean precipitate size increased with increasing irradiation temperature. The examination results are used to provide interpretation of in-reactor creep, density change and post irradiation tensile behavior.

  4. Evaluation of ferritic alloy Fe-2-1/4Cr-1Mo after neutron irradiation - irradiation creep and swelling

    SciTech Connect

    Gelles, D.S.; Puigh, R.J.

    1983-10-01

    Irradiation creep and swelling measurements are reported for Fe-2-1/4Cr-1Mo after irradiation by fast neutrons over the temperature range 390 to 560/sup 0/C. Diameter change measurements on thin walled pressurized tubes in a bainitic condition and density change measurements on rods in a nonstandard condition were made following irradiation in the Experimental Breeder Reactor II. The irradiation creep specimens were irradiated to a fluence of 5.7 x 10/sup 22/ n/cm/sup 2/ (E > 0.1 MeV) or 30 dpa and the swelling specimens were irradiated to a peak fluence of 2.4 x 10/sup 23/ n/cm/sup 2/ or 115 dpa. These results have been used as a basis to establish in-reactor creep and swelling correlations for 2-1/4Cr-1Mo in a bainitic condition. The correlations predict moderate swelling and moderate irradiation enhanced creep at 390/sup 0/C.

  5. Wear of UHMWPE against nitrogen-ion-implanted and NbN-coated Co-Cr-Mo alloy formed by plasma immersion ion implantation and deposition for artificial joints

    NASA Astrophysics Data System (ADS)

    Park, Won-Woong; Kim, Eun-Kyeom; Jeon, Jun-Hong; Choi, Jin-Young; Moon, Sun-Woo; Lim, Sang-Ho; Han, Seung-Hee

    2012-08-01

    NbN thin film was deposited on the Co-Cr-Mo alloy by plasma immersion ion implantation and deposition (PIII&D) to reduce the volume wear rate of UHMWPE. In addition, nitrogen ions were implanted on the surface of the Co-Cr-Mo alloy prior to the NbN film deposition in order to increase the hardness of the substrate. XPS analysis revealed that nitrogen ions were implanted into the surface of the Co-Cr-Mo alloy, leading to the formation of CrN and Cr2N. The UHMWPE volume wear rate was measured using a pin-on-disk tribometer. The wear test result showed that the volume wear rate of UHMWPE against NbN-coated Co-Cr-Mo alloy declined by 20% as compared to that in the untreated Co-Cr-Mo alloy. In addition, the UHMWPE wear rate against the nitrogen-ion-implanted and NbN-coated Co-Cr-Mo alloy could be drastically reduced by up to 48%. It can be concluded that a combination of prior nitrogen ion implantation and NbN coating via PIII&D is a promising surface treatment tool for extending the lifetime of metal-on-polymer artificial joints.

  6. X-ray diffraction study of BaTiO3 single crystals before and after fast-neutron irradiation

    NASA Astrophysics Data System (ADS)

    Stash, A. I.; Ivanov, S. A.; Stefanovich, S. Yu.; Mosunov, A. V.; Boyko, V. M.; Ermakov, V. S.; Korulin, A. V.; Kalyukanov, A. I.; Isakova, N. N.

    2015-09-01

    The neutron irradiation of ferroelectrics is efficiently used to form structural states that cannot be obtained by conventional technologies. To date, the effect of neutron irradiation on the structure and properties of BaTiO3 has been studied for only ceramic materials. We have considered the influence of fast-neutron irradiation ( F = 1 × 1017 cm-2) on the structure and properties of BaTiO3 single crystals for the first time. The structural changes occurring in irradiated BaTiO3 and their correlation with the behavior of dielectric and nonlinear optical characteristics are analyzed with the aid of a specially developed method for taking into account the experimental correction to diffuse scattering. Neutron irradiation to the aforementioned dose retains the polar structure of the material and only slightly changes atomic displacements. The radiationinduced structural changes occur according to the high-temperature type to form a structure similar to the cubic modification of unirradiated BaTiO3 crystal.

  7. Inverse magnetocaloric effect in Ce(Fe0.96Ru0.04)2: Effect of fast neutron irradiation

    NASA Astrophysics Data System (ADS)

    Dube, V.; Mishra, P. K.; Rajarajan, A. K.; Prajapat, C. L.; Sastry, P. U.; Thakare, S. V.; Singh, M. R.; Ravikumar, G.

    2013-02-01

    We have shown the effect of fast neutron irradiation on the magnetic phase transition and magnetocaloric effect (MCE) in a doped Ce(Fe0.96Ru0.04)2, intermettalic. We show that this leads to suppression of MCE and a to a disordered ferromagnetic phase.

  8. Tritium Retention and Permeation in Ion- and Neutron-Irradiated Tungsten under US-Japan PHENIX Collaboration

    NASA Astrophysics Data System (ADS)

    Shimada, Masashi; Taylor, Chase N.; Kolasinski, Robert D.; Buchenauer, Dean A.; Chikada, Takumi; Oya, Yasuhisa; Hatano, Yuji

    2015-11-01

    A critical challenge for long-term operation of ITER and beyond to a FNSF, a DEMO and future fusion reactor will be the development of plasma-facing components (PFCs) that demonstrate erosion resistance to intense heat and neutral/ion particle fluxes under the extreme fusion nuclear environment, while minimizing in-vessel inventories and ex-vessel permeation of tritium. Recent work at Tritium Plasma Experiment demonstrated that tritium diffuses in bulk tungsten at elevated temperatures, and can be trapped in radiation-induced trap site (up to 1 at. % T/W) in tungsten [M. Shimada, et.al., Nucl. Fusion 55 (2015) 013008]. US-Japan PHENIX collaboration (2013-2019) investigates irradiation response on tritium behavior in tungsten, and performs one-of-a-kind neutron-irradiation with Gd thermal neutron shield at High Flux Isotope Reactor, ORNL. This presentation describes the challenge in elucidating tritium behavior in neutron-irradiated PFCs, the PHENIX plans for neutron-irradiation and post irradiation examination, and the recent findings on tritium retention and permeation in 14MeV neutron-irradiated and Fe ion irradiated tungsten. This work was prepared for the U.S. Department of Energy, Office of Fusion Energy Sciences, under the DOE Idaho Field Office contract number DE-AC07-05ID14517.

  9. Antiradiation Vaccine: Technology Development Of Prophylaxis, Prevention And Treatment Of Biological Consequences And Complications After Neutron Irradiation.

    NASA Astrophysics Data System (ADS)

    Popov, Dmitri; Maliev, Slava; Jones, Jeffrey

    Introduction: Neutrons irradiation produce a unique biological effectiveness compare to different types of radiation because their ability to create a denser trail of ionized atoms in biological living tissues[Straume 1982; Latif et al.2010; Katz 1978; Bogatyrev 1982]. The efficacy of an Anti-Radiation Vaccine for the prophylaxis, prevention and therapy of acute radiation pathology was studied in a neutron exposure facility. The biological effects of fast neutrons include damage of central nervous system and cardiovascular system with development of Acute Cerebrovascular and Cardiovascular forms of acute radiation pathology. After irradiation by high doses of fast neutron, formation of neurotoxins, hematotoxins,cytotoxins forming from cell's or tissue structures. High doses of Neutron Irradiation generate general and specific toxicity, inflammation reactions. Current Acute Medical Management and Methods of Radiation Protection are not effective against moderate and high doses of neutron irradiation. Our experiments demonstrate that Antiradiation Vaccine is the most effective radioprotectant against high doses of neutron-radiation. Radiation Toxins(biological substances with radio-mimetic properties) isolated from central lymph of gamma-irradiated animals could be working substance with specific antigenic properties for vaccination against neutron irradiation. Methods: Antiradiation Vaccine preparation standard - mixture of a toxoid form of Radiation Toxins - include Cerebrovascular RT Neurotoxin, Cardiovascular RT Neurotoxin, Gastrointestinal RT Neurotoxin, Hematopoietic RT Hematotoxin. Radiation Toxins were isolated from the central lymph of gamma-irradiated animals with different forms of Acute Radiation Syndromes - Cerebrovascular, Cardiovascular, Gastrointestinal, Hematopoietic forms. Devices for Y-radiation were "Panorama","Puma". Neutron exposure was accomplished at the Department of Research Institute of Nuclear Physics, Dubna, Russia. The neutrons

  10. Effect of neutron-irradiation on the microstructure of a Fe-12at.%Cr alloy

    NASA Astrophysics Data System (ADS)

    Kuksenko, V.; Pareige, C.; Genevois, C.; Cuvilly, F.; Roussel, M.; Pareige, P.

    2011-08-01

    A nanoscale description of the microstructure in a Fe-12at%Cr model alloy of low purity which has been neutron irradiated at 300°C up to 0.6 dpa, has been performed owing to atom probe tomography (APT). APT investigations have shown that the impurities are also involved in the microstructural evolution under irradiation. Two different populations of clusters have been observed: Cr-enriched and NiSiPCr-enriched clusters. As expected with a process of enhanced precipitation, Cr-enriched clusters are homogeneously distributed inside grains and certainly not correlated to dislocation loops. The NiSiPCr-enriched clusters, which are probably radiation induced segregations, are independent of the Cr-enriched clusters and are also homogeneously distributed. A quantitative description of these objects is presented in this paper and results are compared to SANS data of the literature obtained for the same model alloy.

  11. Hardness of Carburized Surfaces in 316LN Stainless Steel after Low Temperature Neutron Irradiation

    SciTech Connect

    Byun, TS

    2005-01-31

    A proprietary surface carburization treatment is being considered to minimize possible cavitation pitting of the inner surfaces of the stainless steel target vessel of the SNS. The treatment gives a large supersaturation of carbon in the surface layers and causes substantial hardening of the surface. To answer the question of whether such a hardened layer will remain hard and stable during neutron irradiation, specimens of the candidate materials were irradiated in the High Flux Isotope Reactor (HFIR) to an atomic displacement level of 1 dpa. Considerable radiation hardening occurred in annealed 316LN stainless steel and 20% cold rolled 316LN stainless steel, and lesser radiation hardening in Kolsterised layers on these materials. These observations coupled with optical microscopy examinations indicate that the carbon-supersaturated layers did not suffer radiation-induced decomposition and softening.

  12. The effects of neutron irradiation on fracture toughness of austenitic stainless steels.

    SciTech Connect

    Chopra, O. K.; Gruber, E. E.; Shack, W. J.

    1999-05-21

    Austenitic stainless steels are used extensively as structural alloys in reactor pressure vessel internal components because of their superior fracture toughness properties. However, exposure to high levels of neutron irradiation for extended periods leads to significant reduction in the fracture resistance of these steels. This paper presents results of fracture toughness J-R curve tests on four heats of Type 304 stainless steel that were irradiated to fluence levels of {approx}0.3 and 0.9 x 10{sup 21} n cm{sup {minus}2} (E >1 MeV) at {approx}288 C in a helium environment in the Halden heavy water boiling reactor. The tests were performed on 1/4-T compact tension specimens in air at 288 C; crack extensions were determined by both DC potential and elastic unloading compliance techniques.

  13. Microstructure and mechanical properties of neutron irradiated V-20Ti alloy

    NASA Astrophysics Data System (ADS)

    Higashiguchi, Y.; Kayano, H.; Morozumi, S.

    1985-08-01

    Neutron irradiation damage and its effects on mechanical properties were studied for V-20Ti alloy with three different fluences: 5 × 10 24, 2 × 10 24 and 1× 10 23 n m -2 ( E > l MeV) , named A-, B- and C-specimens, respectively. Radiation-induced precipitates (RIP) were observed in A and B specimens and no voids in all specimens. It was clear from the detailed investigation that the precipitates are circular and planar coherent particles lying on (100) planes and have the fee structures. The mechanisms for suppression of void formation and for softening the irradiation effects on the mechanical properties were suggested based on the relation with radiation-induced precipitates (RIP) which were considered as a non-stoichiometric suboxide and contained many vacancies at lattice sites.

  14. Effect of neutron irradiation on the tensile properties and microstructure of several vanadium alloys

    SciTech Connect

    Braski, D.N.

    1986-01-01

    Specimens of V-15Cr-5Ti, VANSTAR-7, and V-3Ti-1Si were encapsulated in TZM tubes containing /sup 7/Li to prevent interstitial pickup and irradiated in FFTF (MOTA experiment) to a damage level of 40 dpa. The irradiation temperatures were 420, 520, and 600/sup 0/C. For a better simulation of fusion reactor conditions, helium was preimplanted in some specimens using a modified version of the ''tritium trick.'' The V-15Cr-5Ti alloy was most susceptible to irradiation hardening and helium embrittlement, followed by VANSTAR-7 and V-3Ti-1Si. VANSTAR-7 exhibited a relatively high maximum void swelling of approx.6% at 520/sup 0/C while V-15Cr-5Ti and V-3Ti-1Si had values of less than 0.3% at all three temperatures. The V-3Ti-1Si clearly outperformed the other two vanadium alloys in resisting the effects of neutron irradiation.

  15. Relationship of microstructure and tensile properties for neutron-irradiated vanadium alloys

    SciTech Connect

    Loomis, B.A.; Smith, D.L.

    1990-01-01

    The microstructures in V-15Cr-5Ti, V-10Cr-5RTi, V-3Ti-1Si, V-15Ti-7.5Cr, and V-20Ti alloys were examined by transmission electron microscopy after neutron irradiation at 600{degree}C to 21--84 atom displacements per atom in the Materials Open Test Assembly of the Fast Flux Test Facility. The microstructures in these irradiated alloys were analyzed to determine the radiation-produced dislocation density, precipitate number density and size, and void number density and size. The results of these analyses were used to compute increases in yield stress and swelling of the irradiated alloys. The computed increase in yield stress was compared with the increase in yield stress determined from tensile tests on these irradiated alloys. This comparison made it possible to evaluate the influence of alloy composition on the evolution of radiation-damaged microstructures and the resulting tensile properties. 11 refs.

  16. Temperature dependence of the deformation behavior of 316 stainless steel after low temperature neutron irradiation

    SciTech Connect

    Pawel-Robertson, J.E.; Rowcliffe, A.F.; Grossbeck, M.L.

    1996-10-01

    The effects of low temperature neutron irradiation on the tensile behavior of 316 stainless steel have been investigated. A single heat of solution annealed 316 was irradiated to 7 and 18 dpa at 60, 200, 330, and 400{degrees}C. The tensile properties as a function of dose and as a function of temperature were examined. Large changes in yield strength, deformation mode, strain to necking, and strain hardening capacity were seen in this irradiation experiment. The magnitudes of the changes are dependent on both irradiation temperature and neutron dose. Irradiation can more than triple the yield strength over the unirradiated value and decrease the strain to necking (STN) to less than 0.5% under certain conditions. A maximum increase in yield strength and a minimum in the STN occur after irradiation at 330{degrees}C but the failure mode remains ductile.

  17. High dose effects in neutron irradiated face-centered cubic metals

    SciTech Connect

    Garner, F.A.; Toloczko, M.B.

    1993-06-01

    During neutron irradiation, most face-centered cubic metals and alloys develop saturation or quasi-steady state microstructures. This, in turn, leads to saturation levels in mechanical properties and quasi-steady state rates of swelling and creep deformation. Swelling initially plays only a small role in determining these saturation states, but as swelling rises to higher levels, it exerts strong feedback on the microstructure and its response to environmental variables. The influence of swelling, either directly or indirectly via second order mechanisms, such as elemental segregation to void surfaces, eventually causes major changes, not only in irradiation creep and mechanical properties, but also on swelling itself. The feedback effects of swelling on irradiation creep are particularly complex and lead to problems in applying creep data derived from highly pressurized creep tubes to low stress situations, such as fuel pins in liquid metal reactors.

  18. Effects of silicon, carbon and molybdenum additions on IASCC of neutron irradiated austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Nakano, J.; Miwa, Y.; Kohya, T.; Tsukada, T.

    2004-08-01

    To study the effects of minor elements on irradiation assisted stress corrosion cracking (IASCC), high purity type 304 and 316 stainless steels (SSs) were fabricated and minor elements, Si or C were added. After neutron irradiation to 3.5 × 10 25 n/m 2 ( E>1 MeV), slow strain rate tests (SSRTs) of irradiated specimens were conducted in oxygenated high purity water at 561 K. Specimen fractured surfaces were examined using a scanning electron microscope (SEM) after the SSRTs. The fraction of intergranular stress corrosion cracking (IGSCC) on the fractured surface after the SSRTs increased with neutron fluence. In high purity SS with added C, the fraction of IGSCC was the smallest in the all SSs, although irradiation hardening level was the largest of all the SSs. Addition of C suppressed the susceptibility to IGSCC.

  19. Fast neutron irradiation effects on magnetization relaxation in YBCO single crystals

    SciTech Connect

    Lensink, J.G.; Griessen, R.; Wiesinger, H.P.; Sauerzopf, F.M.; Weber, H.W.; Crabtree, G.W.

    1991-07-01

    A high-quality YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} single crystal has been investigated by torque magnetometry prior to and following fast neutron irradiation to a fluence of 2{times}10{sup 21} m{sup {minus}2} (E > 0.1 MeV). In addition to large enhancements of the critical current densities, which have been observed in similar form previously by Sauerzopf et al, we find a dramatic change in the relaxation behavior following irradiation. At low temperatures ({le} 50 k) the relaxation rates are lowered by factors up to 4 in the irradiated state in a magnetic field of 1.5 T. At higher temperatures, on the other hand, they are enhanced compared to the unirradiated state. Both before and after irradiation, the magnetization relaxation follows a logarithmic time dependence, which we ascribe to thermally activated flux motion.

  20. Micromechanisms of Twin Nucleation in TiAl: Effects of Neutron Irradiation

    SciTech Connect

    Hishinuma, A.; Yoo, M.H.

    1999-01-28

    The so-called radiation-induced ductility (RID) reported in neutron-irradiated 47at%Al alloys is attributed to the formation of effective twin embryos in the presence of interstitial-type Frank loops in {gamma}-TiAl and the subsequent nucleation and growth of microtwins during post-irradiation tensile deformation. The stability of large faulted Frank loops is explained in terms of the repulsive interaction between Shockley and Frank partials. Interaction of only six ordinary slip dislocations with a Frank loop can facilitate a pole mechanism for twin formation to work. The relative ease of heterogeneous twin nucleation is the reason for the RID and the lack of changes in yield strength and work hardening.

  1. Separation and Quantification of Chemically Diverse Analytes in Neutron Irradiated Fissile Materials

    SciTech Connect

    Douglas, Matthew; Friese, Judah I.; Greenwood, Lawrence R.; Farmer, Orville T.; Thomas, Linda MP; Maiti, Tapas C.; Finn, Erin C.; Garofoli, Stephanie J.; Gassman, Paul L.; Huff, Morgan M.; Schulte, Shannon M.; Smith, Steven C.; Thomas, Kathie K.; Bachelor, Paula P.

    2009-10-01

    Quantitative measurement of fission and activation products resulting from neutron irradiation of fissile materials is of interest for applications in environmental monitoring, nuclear waste management, and national security. To overcome mass and spectral interferences, and the relative small quantities of some target analytes, an extensive series of chemical separations is necessary. Based on established separations processes involving co-precipitation, solvent extraction, and ion-exchange and extraction chromatography, we have been evaluating and optimizing a proposed sequence of separation steps to allow for the timely quantification of analytes of interest. For simplicity, much of the chemical separation development work has been performed using stable elements as surrogates for the radioactive material. We have recently evaluated the optimized procedures using an irradiated sample to examine the adequacy of separations for measurement of desired analytes by gamma spectrometry. Here we present the results of this evaluation and describe the radiochemical separations utilized.

  2. ALARA considerations for the whole body neutron irradiation facility source removal project at Brookhaven National Laboratory.

    PubMed

    Sullivan, Patrick T

    2006-02-01

    This paper describes the activities that were involved with the safe removal of fourteen PuBe sources from the Brookhaven National Laboratory (BNL) Whole Body Neutron Irradiation Facility (WBNIF). As part of a Department of Energy and BNL effort to reduce the radiological inventory, the WBNIF was identified as having no future use. In order to deactivate the facility and eliminate the need for nuclear safety management and long-term surveillance, it was decided to remove the neutron sources and dismantle the facility. In addition, the sources did not have DOT Special Form documentation so they would need to be encapsulated once removed for offsite storage or disposal. The planning and the administrative as well as engineering controls put in place enabled personnel to safely remove and encapsulate the sources while keeping exposure as low as reasonably achievable (ALARA). PMID:16404183

  3. Characteristics of the Neutron Irradiation Facilities of the PSI Calibration Laboratory

    SciTech Connect

    Hoedlmoser, H.; Schuler, Ch.; Butterweck, G.; Mayer, S.

    2011-12-13

    The neutron radiation fields of the Calibration Laboratory at Paul Scherrer Institute (PSI) are traceable to the national standards of the Physikalisch-Technische Bundesanstalt (PTB) in Germany. A Berthold LB6411 neutron dose rate meter for neutron radiation is used as a secondary standard. Recently, a thorough characterization of the neutron irradiation fields of the {sup 241}Am-Be and {sup 252}Cf sources by means of reference measurements and a detailed MCNPX simulation of the irradiation facility has been initiated. In this work, the characteristics of the neutron radiation fields are summarized and presented together with model equations and an uncertainty analysis. MCNPX results are shown for the {sup 241}Am-Be source. A comparison of measured and simulated data shows an excellent agreement. From the simulation, valuable information about the neutron fields like the contribution of scattered neutrons in the fields and the energy spectra could be obtained.

  4. The effect of neutron irradiation on the mechanical properties of C/SiC composites

    SciTech Connect

    Shih, Chunghao; Katoh, Yutai; Snead, Lance Lewis; Steinbeck, John

    2013-01-01

    The effects of neutron irradiation to 3.5 and 9.5 dpa at 730 C on a 2D plain woven carbon fiber reinforced polymer derived SiC matrix composite are presented. For both fluences, the irradiation caused in-plane contraction and trans-plane expansion. Irradiation also caused substantial reduction in composite flexural strength (54%) and increase in flexural tangent modulus (+85%). The extents of dimensional/ mechanical property changes were greater for the higher fluence irradiated samples. Those changes suggest the instability of the polymer derived SiC matrix following irradiation. The nature of the mechanical property changes suggest increased clamping stress between the fiber and the matrix. The composite property changes are explained in terms of irradiation effects on composite constituents and are compared with carbon fiber reinforced carbon matrix composite as a reference material.

  5. Additive analysis of nano silicon under the influence of neutron irradiation

    NASA Astrophysics Data System (ADS)

    Garibli, Aydan; Huseynov, Elchin; Garibov, Adil; Mehdiyeva, Ravan

    2016-04-01

    Nano silicon with 80m2g‑1 specific surface area, 100 nm size and 0.08 g/cm3 density has been irradiated continuously with neutrons (2 × 1013n ṡcm‑2s‑1) up to 20 h at various periods in TRIGA Mark II type research reactor. After the neutron irradiation, cooling time of the samples is taken approximately 360 h. It is found that the initial radioactivity of the irradiated samples changes within 0.1 kBq-3.1 GBq range. Definition of elements’ concentration is determined based on the activities formed in the relevant energy range. After the irradiation, the result of activity analysis carried out the element content of 1% mixture existing in nano Si which has been defined with radionuclides of the relevant element. Moreover, from activities of mixed radioisotopes, their amounts in percentage has been determined.

  6. Microvascular response of striated muscle to common arthroplasty-alloys: A comparative in vivo study with CoCrMo, Ti-6Al-4V, and Ti-6Al-7Nb.

    PubMed

    Kraft, Clayton N; Burian, Björn; Diedrich, Oliver; Gessmann, Jan; Wimmer, Markus A; Pennekamp, Peter H

    2005-10-01

    The impairment of skeletal muscle microcirculation by a biomaterial may have profound consequences. Due to excellent physical and corrosion characteristics, CoCrMo-, Ti-6Al-4V-, and Ti-6Al-7Nb-alloys are commonly used in orthopedic surgery. Yet concern has been raised with regard to the implications of inevitable corrosion product of these metals on the surrounding biologic environment, particularly in the case of CoCrMo. We, therefore, studied in vivo nutritive perfusion and leukocytic response of striated muscle to these alloys, thereby drawing conclusions on their inflammatory potential. In 28 hamsters, utilizing the dorsal skinfold chamber preparation and intravital microscopy, we could demonstrate that the implant material CoCrMo has a marked impact on local microvascular parameters. While the Ti-alloys Ti-6Al-4V and Ti-6Al-7Nb induced only a transient and moderate inflammatory response, the implantation of a CoCrMo sample led to a distinct and persistent activation of leukocytes combined with disruption of the microvascular endothelial integrity and marked leukocyte extravasation. Animals with Ti-alloys showed a clear tendency of recuperation, while in all but one CoCrMo-treated animals, a breakdown of microcirculation prior to the scheduled end of the experiment was observed. Overall, the alloy Ti-6Al-7Nb was tolerated slightly better than Ti-6Al-4V under the chosen test conditions, though this discrepancy was not statistically significant. Conclusively, the commonly used biomaterials Ti-6Al-7Nb and Ti-6Al-4V induce a considerably lower inflammatory response in the skeletal muscle microvascular system, compared to a CoCrMo-alloy. With a minimum of adverse host reaction, our results indicate that for this particular model Ti-alloys are better tolerated than CoCrMo implant materials.

  7. Generation of peanut mutants by fast neutron irradiation combined with in vitro culture.

    PubMed

    Wang, Jing-Shan; Sui, Jiong-Ming; Xie, Yong-Dun; Guo, Hui-Jun; Qiao, Li-Xian; Zhao, Li-Lan; Yu, Shan-Lin; Liu, Lu-Xiang

    2015-05-01

    Induced mutations have played an important role in the development of new plant varieties. In this study, we investigated the effects of fast neutron irradiation on somatic embryogenesis combined with plant regeneration in embryonic leaflet culture to develop new peanut (Arachis hypogaea L.) germplasm for breeding. The dry seeds of the elite cultivar Luhua 11 were irradiated with fast neutrons at dosages of 9.7, 14.0 and 18.0 Gy. The embryonic leaflets were separated and incubated in a medium with 10.0-mg/l 2,4-D to induce somatic embryogenesis. Next, they were incubated in a medium with 4.0-mg/l BAP for plant regeneration. As the irradiation dosage increased, the frequency of both somatic embryo formation and plantlet regeneration decreased. The regenerated plantlets were grafted onto rootstocks and were transplanted into the field. Later, the mature seeds of the regenerated plants were harvested. The M2 generation plants from most of the regenerated cultivars exhibited variations and segregation in vigor, plant height, branch and pod number, pod size, and pod shape. To determine whether the phenotypes were associated with genomic modification, we compared the DNA polymorphisms between the wild-type plants and 19 M3-generation individuals from different regenerated plants. We used 20 pairs of simple sequence repeat (SSR) primers and detected polymorphisms between most of the mutants and the wild-type plants (Luhua 11). Our results indicate that using a combination of fast neutron irradiation and tissue culture is an effective approach for creating new peanut germplasm.

  8. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    SciTech Connect

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Wirth, Brian D; Snead, Lance Lewis

    2016-01-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (~90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutron irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S–W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage. This provides insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.

  9. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    NASA Astrophysics Data System (ADS)

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Snead, Lance L.; Wirth, Brian D.

    2016-03-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (∼90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutron irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S-W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage, providing insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.

  10. Generation of peanut mutants by fast neutron irradiation combined with in vitro culture.

    PubMed

    Wang, Jing-Shan; Sui, Jiong-Ming; Xie, Yong-Dun; Guo, Hui-Jun; Qiao, Li-Xian; Zhao, Li-Lan; Yu, Shan-Lin; Liu, Lu-Xiang

    2015-05-01

    Induced mutations have played an important role in the development of new plant varieties. In this study, we investigated the effects of fast neutron irradiation on somatic embryogenesis combined with plant regeneration in embryonic leaflet culture to develop new peanut (Arachis hypogaea L.) germplasm for breeding. The dry seeds of the elite cultivar Luhua 11 were irradiated with fast neutrons at dosages of 9.7, 14.0 and 18.0 Gy. The embryonic leaflets were separated and incubated in a medium with 10.0-mg/l 2,4-D to induce somatic embryogenesis. Next, they were incubated in a medium with 4.0-mg/l BAP for plant regeneration. As the irradiation dosage increased, the frequency of both somatic embryo formation and plantlet regeneration decreased. The regenerated plantlets were grafted onto rootstocks and were transplanted into the field. Later, the mature seeds of the regenerated plants were harvested. The M2 generation plants from most of the regenerated cultivars exhibited variations and segregation in vigor, plant height, branch and pod number, pod size, and pod shape. To determine whether the phenotypes were associated with genomic modification, we compared the DNA polymorphisms between the wild-type plants and 19 M3-generation individuals from different regenerated plants. We used 20 pairs of simple sequence repeat (SSR) primers and detected polymorphisms between most of the mutants and the wild-type plants (Luhua 11). Our results indicate that using a combination of fast neutron irradiation and tissue culture is an effective approach for creating new peanut germplasm. PMID:25653418

  11. Technical Letter Report on the Cracking of Irradiated Cast Stainless Steels with Low Ferrite Content

    SciTech Connect

    Chen, Y.; Alexandreanu, B.; Natesan, K.

    2014-11-01

    Crack growth rate and fracture toughness J-R curve tests were performed on CF-3 and CF-8 cast austenite stainless steels (CASS) with 13-14% of ferrite. The tests were conducted at ~320°C in either high-purity water with low dissolved oxygen or in simulated PWR water. The cyclic crack growth rates of CF-8 were higher than that of CF-3, and the differences between the aged and unaged specimens were small. No elevated SCC susceptibility was observed among these samples, and the SCC CGRs of these materials were comparable to those of CASS alloys with >23% ferrite. The fracture toughness values of unirradiated CF-3 were similar between unaged and aged specimens, and neutron irradiation decreased the fracture toughness significantly. The fracture toughness of CF-8 was reduced after thermal aging, and declined further after irradiation. It appears that while lowering ferrite content may help reduce the tendency of thermal aging embrittlement, it is not very effective to mitigate irradiation-induced embrittlement. Under a combined condition of thermal aging and irradiation, neutron irradiation plays a dominant role in causing embrittlement in CASS alloys.

  12. Use of a High-flux Atomic Oxygen Source for MBE growth of the di- and tri- oxides of Cr, Mo, and W

    NASA Astrophysics Data System (ADS)

    Ingle, Nicholas; Hammond, Robert; Beasley, Malcolm

    2000-03-01

    The MBE growth of several of the highly oxidized phases of the Group IIB elements (Cr, Mo, and W) are of great current interest. In particular, CrO_2, a theorized half-metallic ferromagnet, has yet to be grown in a form that allows high quality tunneling measurements to be performed. Also, thin films of WO3 for controlled Na doping studies are of interest to help understand the recently published results on possible superconductivity in this material(S. Reich and Y. Tsabba, EUROPEAN PHYSICAL JOURNAL B v. 9(1) pp. 1-4 MAY 1999 and Shengelaya A, Reich S, Tsabba Y, and Muller KA EUROPEAN PHYSICAL JOURNAL B , v. 12(1) pp. 13-15 NOV 1999). Using a new high-flux atomic oxygen source and detection scheme, RHEED, and in-situ core-level photoemission we present the atomic oxygen-temperature phase diagrams indicating the conditions under which the di- and tri- oxide phases of Cr, Mo, and W can be grown.

  13. Influence of the sliding velocity and the applied potential on the corrosion and wear behavior of HC CoCrMo biomedical alloy in simulated body fluids.

    PubMed

    Gil, Roberto Alonso; Muñoz, Anna Igual

    2011-11-01

    The corrosion and tribocorrosion behavior of an as-cast high carbon CoCrMo alloy immersed in phosphate buffered solution (PBS) and phosphate buffered solution with bovine serum albumin (PBS+BSA) have been analyzed by electrochemical techniques and surface microscopy. After the electrochemical characterization of the alloy in both solutions, the sample was studied tribo-electrochemically (by open circuit potential, OCP measurements, potentiodynamic curves and potentiostatic tests) in a ball-on-disk tribometer rotating in different sliding velocities. The influence of solution chemistry, sliding velocity and applied potential on the corrosion and tribocorrosion behavior of the CoCrMo alloy has been studied. Anodic current density increases with sliding velocity but wear rate does not change at an applied anodic potential; on the other hand, BSA modifies the wear debris behavior (by agglomerating the debris formed by mechanical removal of particles) thus increasing the mechanical wear volume. Under cathodic conditions, cathodic current density also increases during mechanical contact while the wear rate decreases with sliding velocity and BSA lubricates the contact thus reducing the total wear volume with respect to the non-containing BSA solution. The work shows how the electrode potential critically affects the corrosion and tribocorrosion rates by increasing the wear coefficients at applied anodic potentials due to severe wear accelerated corrosion.

  14. Boundary lubrication of stainless steel and CoCrMo alloy based on phosphorous and boron compounds in oil-in-water emulsion

    NASA Astrophysics Data System (ADS)

    Yan, Jincan; Zeng, Xiangqiong; Ren, Tianhui; van der Heide, Emile

    2014-10-01

    Emulsion lubrication is widely used in metal forming operations and has potential applications in the biomedical field, yet the emulsion lubrication mechanism is not well understood. This work explores the possibilities of three different oil-in-water (O/W) emulsions containing dibutyl octadecylphosphoramidate (DBOP), 6-octadecyl-1,3,6,2-dioxazaborocan-2-ol calcium salt (ODOC) and 2-(4-dodecylphenoxy)-6-octadecyl-1,3,6,2-dioxazaborocane (DOB) to generate boundary films on stainless steel AISI 316 and CoCrMo alloy surfaces. Experimental results show lower friction values for the emulsions in combination with CoCrMo compared to AISI 316. The different performance of the additives is related to the composition of the adsorption and reaction film on the interacting surfaces, which was shown to be dependent on the active elements and molecular structure of the additives. The friction profile of the emulsions indicates that the emulsion appears to be broken during the rubbing process, then the additives adsorb onto the metal surface to form protecting boundary layers. The XPS analysis shows that for boundary lubrication conditions, the additive molecules in the emulsion first adsorb on the metal surface after the droplet is broken, and then decompose and react with the metal surface during the rubbing process to form stable lubricating films on the rubbed surfaces.

  15. Deformation Behavior and Microstructure Evolution of As-Cast 42CrMo Alloy in Isothermal and Non-isothermal Compression

    NASA Astrophysics Data System (ADS)

    Qin, Fangcheng; Li, Yongtang; Qi, Huiping; Lv, Zhenhua

    2016-09-01

    The isothermal and non-isothermal multi-pass compression tests of centrifugal casting 42CrMo steel were conducted on a Gleeble-3500 thermal simulation machine. The effects of compression passes and finishing temperatures on deformation behavior and microstructure evolution were investigated. It is found that the microstructure is homogeneous with equiaxed grains, and the flow stress does not show significant change with the increase in passes, while the peak softening coefficient increases first and then decreases during inter-pass. Moreover, the dominant mechanisms of controlled temperature and accumulated static recrystallization for grain refinement and its homogeneous distribution are found after 5 passes deformation. As the finishing temperature increases, the flow stress decreases gradually, but the dynamic recrystallization accelerates and softening effect increases, resulting in the larger grain size and homogeneous microstructure. The microhardness decreases sharply because the sufficient softening occurs in microstructure. When the finishing temperature is 890 °C, the carbide particles are precipitated in the vicinity of the grain boundaries, thus inhibiting the dislocation motion. Thus, the higher finishing temperature (≥970 °C) for centrifugal casting 42CrMo alloy should be avoided in non-isothermal multi-pass deformation, which is beneficial to grain refinement and properties improvement.

  16. Design and Demonstration of a Material-Plasma Exposure Target Station for Neutron Irradiated Samples

    SciTech Connect

    Rapp, Juergen; Aaron, A. M.; Bell, Gary L.; Burgess, Thomas W.; Ellis, Ronald James; Giuliano, D.; Howard, R.; Kiggans, James O.; Lessard, Timothy L.; Ohriner, Evan Keith; Perkins, Dale E.; Varma, Venugopal Koikal

    2015-10-20

    Fusion energy is the most promising energy source for the future, and one of the most important problems to be solved progressing to a commercial fusion reactor is the identification of plasma-facing materials compatible with the extreme conditions in the fusion reactor environment. The development of plasma–material interaction (PMI) science and the technology of plasma-facing components are key elements in the development of the next step fusion device in the United States, the so-called Fusion Nuclear Science Facility (FNSF). All of these PMI issues and the uncertain impact of the 14-MeV neutron irradiation have been identified in numerous expert panel reports to the fusion community. The 2007 Greenwald report classifies reactor plasma-facing materials (PFCs) and materials as the only Tier 1 issues, requiring a “. . . major extrapolation from the current state of knowledge, need for qualitative improvements and substantial development for both the short and long term.” The Greenwald report goes on to list 19 gaps in understanding and performance related to the plasma–material interface for the technology facilities needed for DEMO-oriented R&D and DEMO itself. Of the 15 major gaps, six (G7, G9, G10, G12, G13) can possibly be addressed with ORNL’s proposal of an advanced Material Plasma Exposure eXperiment. Establishing this mid-scale plasma materials test facility at ORNL is a key element in ORNL’s strategy to secure a leadership role for decades of fusion R&D. That is to say, our end goal is to bring the “signature facility” FNSF home to ORNL. This project is related to the pre-conceptual design of an innovative target station for a future Material–Plasma Exposure eXperiment (MPEX). The target station will be designed to expose candidate fusion reactor plasma-facing materials and components (PFMs and PFCs) to conditions anticipated in fusion reactors, where PFCs will be exposed to dense high-temperature hydrogen plasmas providing steady

  17. Long-term strength and allowable stresses of grade 10Kh9MFB and X10CrMoVNb9-1 (T91/P91) chromium heat-resistant steels

    NASA Astrophysics Data System (ADS)

    Skorobogatykh, V. N.; Danyushevskiy, I. A.; Schenkova, I. A.; Prudnikov, D. A.

    2015-04-01

    Currently, grade X10CrMoVNb9-1 (T91, P91) and 10Kh9MFB (10Kh9MFB-Sh) chromium steels are widely applied in equipment manufacturing for thermal power plants in Russia and abroad. Compilation and comparison of tensile, impact, and long-term strength tests results accumulated for many years of investigations of foreign grade X10CrMoVNb9-1, T91, P91, and domestic grade 10Kh9MFB (10Kh9MFB-Sh) steels is carried out. The property identity of metals investigated is established. High strength and plastic properties of steels, from which pipes and other products are made, for operation under creep conditions are confirmed. Design characteristics of long-term strength on the basis of tests with more than one million of hour-samples are determined ( and at temperatures of 500-650°C). The table of recommended allowable stresses for grade 10Kh9MFB, 10Kh9MFB-SH, X10CrMoVNb9-1, T91, and P91 steels is developed. The long-time properties of pipe welded joints of grade 10Kh9MFB+10Kh9MFB, 10Kh9MFB-Sh+10Kh9MFB-Sh, X10CrMoVNb9-1+X10CrMoVNb9-1, P91+P91, T91+T91, 10Kh9MFB (10Kh9MFB-Sh)+X10CrMoVNb9-1(T/P91) steels is researched. The welded joint reduction factor is experimentally determined.

  18. Temper and neutron irradiation embrittlement in 2 1/4 Cr-1 Mo steels for pressure vessels of high-temperature gas-cooled reactors

    SciTech Connect

    Suzuki, M.; Fukaya, K.; Kodaira, T.; Oku, T.

    1984-09-01

    A 2 1/4 Cr-1 Mo steel is a promising candidate material for structural components of the pressure vessel of the experimental very high temperature gascooled reactor (VHTR) in Japan. Since the service temperature of such components is expected to be about 400/sup 0/C, the behavior of the temper and neutron irradiation embrittlements in these chromium-molybdenum steels should be confirmed from the viewpoint of structural integrity. The experimental verification on the degree of the embrittlement due to thermal aging, including the effect of applied stress and neutron irradiation, is described. Steel containing substantial amounts (about 100 ppm) of phosphorus atoms, which are believed to cause the temper embrittlement, showed that applied stress enhanced the embrittlement due to thermal aging. Embrittlement caused by neutron irradiation appears to be minimal in the case of the material containing <1000 ppm of copper as impurity with neutrons irradiated at about 400/sup 0/C.

  19. Effect of Neutron Irradiation on Properties of Pb(Mg(1/3)Nb(2/3))O3-PbTiO3.

    PubMed

    Kim, Yong-Il; Choi, Namkyoung; Kim, Geunwoo; Lee, Yun-Hee; Baek, Kwang-Sae; Kim, Ki-Bok

    2015-11-01

    The effect of neutron irradiation on the electrical and piezoelectric properties of a PMN-PT [(Pb(Mg(1/3)Nb(2/3))O3-PbTiO3)] single crystal such as permittivity, electrical impedance and piezoelectric constant d33 has been investigated at 1 kHz. The changes of d33 and permittivity depending on the dose of neutron irradiation for all samples of PMN-PT single crystal were found. In all samples, the permittivity, and piezoelectric constant d33 decreased with the increase of irradiation dose. Changes of XRD patterns depending on the dose of neutron irradiation for all samples were found. From the results of XRDs for analyzing the formation of the PMN-PT single crystals in single phase, the neutron irradiation will affect the crystallinity of PMN-PT single crystals. PMID:26726526

  20. The effects of oxide evolution on mechanical properties in proton- and neutron-irradiated Fe-9%Cr ODS steel

    NASA Astrophysics Data System (ADS)

    Swenson, M. J.; Dolph, C. K.; Wharry, J. P.

    2016-10-01

    The objective of this study is to evaluate the effect of irradiation on the strengthening mechanisms of a model Fe-9%Cr oxide dispersion strengthened steel. The alloy was irradiated with protons or neutrons to a dose of 3 displacements per atoms at 500 °C. Nanoindentation was used to measure strengthening due to irradiation, with neutron irradiation causing a greater increase in yield strength than proton irradiation. The irradiated microstructures were characterized using transmission electron microscopy and atom probe tomography (APT). Cluster analysis reveals solute migration from the Y-Ti-O-rich nanoclusters to the surrounding matrix after both irradiations, though the effect is more pronounced in the neutron-irradiated specimen. Because the dissolved oxygen atoms occupy interstitial sites in the iron matrix, they contribute significantly to solid solution strengthening. The dispersed barrier hardening model relates microstructure evolution to the change in yield strength, but is only accurate if solid solution contributions to strengthening are considered simultaneously.

  1. Simultaneous impact of neutron irradiation and sputtering on the surface structure of self–damaged ITER–grade tungsten

    SciTech Connect

    Belyaeva, A. I. Savchenko, A. A.; Galuza, A. A.; Kolenov, I. V.

    2014-07-15

    Simultaneous effects of neutron irradiation and long–term sputtering on the surface relief of ITER–grade tungsten were studied. The effects of neutron–induced displacement damage have been simulated by irradiation of tungsten target with W{sup 6+} ions of 20 MeV energy. Ar{sup +} ions with energy 600 eV were used as imitation of charge exchange atoms in ITER. The surface relief was studied after each sputtering act. The singularity in the WJ–IG surface relief was ascertained experimentally at the first time, which determines the law of roughness extension under sputtering. As follows from the experimental data, the neutron irradiation has not to make a decisive additional contribution in the processes developing under impact of charge exchange atoms only.

  2. The comparison of microstructure and nanocluster evolution in proton and neutron irradiated Fe-9%Cr ODS steel to 3 dpa at 500 °C

    NASA Astrophysics Data System (ADS)

    Swenson, M. J.; Wharry, J. P.

    2015-12-01

    A model Fe-9%Cr oxide dispersion strengthened (ODS) steel was irradiated with protons or neutrons to a dose of 3 displacements per atom (dpa) at a temperature of 500 °C, enabling a direct comparison of ion to neutron irradiation effects at otherwise fixed irradiation conditions. The irradiated microstructures were characterized using transmission electron microscopy and atom probe tomography including cluster analysis. Both proton and neutron irradiations produced a comparable void and dislocation loop microstructure. However, the irradiation response of the Ti-Y-O oxide nanoclusters varied. Oxides remained stable under proton irradiation, but exhibited dissolution and an increase in Y:Ti composition ratio under neutron irradiation. Both proton and neutron irradiation also induced varying extents of Si, Ni, and Mn clustering at existing oxide nanoclusters. Protons are able to reproduce the void and loop microstructure of neutron irradiation carried out to the same dose and temperature. However, since nanocluster evolution is controlled by both diffusion and ballistic impacts, protons are rendered unable to reproduce the nanocluster evolution of neutron irradiation at the same dose and temperature.

  3. Embrittlement of molybdenum-rhenium welds under low and high temperature neutron irradiation

    NASA Astrophysics Data System (ADS)

    Krajnikov, A. V.; Morito, F.; Danylenko, M. I.

    2014-01-01

    The effect of low- and high-temperature neutron irradiation on the tensile strength, microhardness, and fracture mode has been studied for a series of Mo-Re welds with various Re concentrations. Radiation-induced hardening and concurrent ductility reduction are the key after-effects of neutron exposure. Low-temperature irradiation usually leads to a very hard embrittlement. The hardening effect is rather limited and unstable because of the lack of ductility. Irradiated specimens fail by brittle intergranular or transgranular fracture. The damaging effect of neutrons is less pronounced after high-temperature irradiation. The hardening of the matrix is rather high, but irradiated specimens still keep residual plasticity. High-temperature irradiation intensifies homogeneous nucleation of Re-rich phases, and this effect equalises the difference in mechanical properties between the different weld zones. A characteristic ductility loss exposure temperature was found to separate the temperature fields of absolutely brittle and relatively ductile behaviour. It usually varies between 850 K and 1000 K depending on the alloy composition and irradiation conditions.

  4. Neutron-irradiation creep of silicon carbide materials beyond the initial transient

    NASA Astrophysics Data System (ADS)

    Koyanagi, Takaaki; Katoh, Yutai; Ozawa, Kazumi; Shimoda, Kazuya; Hinoki, Tatsuya; Snead, Lance L.

    2016-09-01

    Irradiation creep beyond the transient regime was investigated for various silicon carbide (SiC) materials. The materials examined included polycrystalline or monocrystalline high-purity SiC, nanopowder sintered SiC, highly crystalline and near-stoichiometric SiC fibers (including Hi-Nicalon Type S, Tyranno SA3, isotopically-controlled Sylramic and Sylramic-iBN fibers), and a Tyranno SA3 fiber-reinforced SiC matrix composite fabricated through a nano-infiltration transient eutectic phase process. Neutron irradiation experiments for bend stress relaxation tests were conducted at irradiation temperatures ranging from 430 to 1180 °C up to 30 dpa with initial bend stresses of up to ∼1 GPa for the fibers and ∼300 MPa for the other materials. Initial bend stress in the specimens continued to decrease from 1 to 30 dpa. Analysis revealed that (1) the stress exponent of irradiation creep above 1 dpa is approximately unity, (2) the stress normalized creep rate is ∼1 × 10-7 [dpa-1 MPa-1] at 430-750 °C for the range of 1-30 dpa for most polycrystalline SiC materials, and (3) the effects on irradiation creep of initial microstructures-such as grain boundary, crystal orientation, and secondary phases-increase with increasing irradiation temperature.

  5. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    DOE PAGESBeta

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance Lewis

    2015-07-14

    The Fe Cr Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe Cr Al alloys has not been fully established. In this study, a series of Fe Cr Al alloys with 10 18 wt % Cr and 2.9 4.9 wt % Al were neutron irradiated at 382 C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition.more » Dislocation loops with Burgers vector of a/2 111 and a 100 were detected and quantified. Results indicate precipitation of Cr-rich is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. Furthermore, a structure property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α' precipitates at sufficiently high chromium contents after irradiation.« less

  6. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    SciTech Connect

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance Lewis

    2015-07-14

    The Fe Cr Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe Cr Al alloys has not been fully established. In this study, a series of Fe Cr Al alloys with 10 18 wt % Cr and 2.9 4.9 wt % Al were neutron irradiated at 382 C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition. Dislocation loops with Burgers vector of a/2 111 and a 100 were detected and quantified. Results indicate precipitation of Cr-rich is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. Furthermore, a structure property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α' precipitates at sufficiently high chromium contents after irradiation.

  7. EPR study of new defects in neutron irradiated KS-4V and KU1 fused silica

    NASA Astrophysics Data System (ADS)

    Lagomacini, J. C.; Bravo, D.; Martín, P.; Ibarra, A.; Martín, A.; López, F. J.

    2010-11-01

    Electron paramagnetic resonance (EPR) studies have been carried out on high purity fused silica KS-4V (low OH content) and KU1 (high OH content), irradiated with fast neutrons (E > 0.1 MeV) at a high fluence of 1022 n/m2. The spectrum of irradiated samples shows various well-known types of paramagnetic defects, POR, NBOHC and E'. Their thermal stability has also been studied by heating the samples in air up to 775 °C. A detailed analysis of the spectra shows that the POR spectrum of neutron-irradiated KS-4V and KU1 has two contributions from centres POR(I) and POR(II), which show very different thermal annealing behaviour. POR(I) is identified with the POR centre previously reported, whereas POR(II) is associated to the effects of fast neutrons. Moreover, a new broad line centred at g = 2.02 is reported that we suggest could be associated to oxygen-hole centres in the neighbourhood of the high amount of tracks generated by ion displacement due to fast neutrons.

  8. A target station for plasma exposure of neutron irradiated fusion material samples to reactor relevant conditions

    NASA Astrophysics Data System (ADS)

    Rapp, Juergen; Giuliano, Dominic; Ellis, Ronald; Howard, Richard; Lore, Jeremy; Lumsdaine, Arnold; Lessard, Timothy; McGinnis, William; Meitner, Steven; Owen, Larry; Varma, Venugopal

    2015-11-01

    The Material Plasma Exposure eXperiment (MPEX) is a device planned to address scientific and technological gaps for the development of viable plasma facing components for fusion reactor conditions (FNSF, DEMO). It will have to address the relevant plasma conditions in a reactor divertor (electron density, electron temperature, ion fluxes) and it needs to be able to expose a-priori neutron irradiated samples. A pre design of a target station able to handle activated materials will be presented. This includes detailed MCNP as well as SCALE and MAVRIC calculations for all potential plasma-facing materials to estimate dose rates. Details on the remote handling schemes for the material samples will be presented. 2 point modeling of the linear plasma transport has been used to scope out the parameter range of the anticipated power fluxes to the target. This has been used to design the cooling capability of the target. The operational conditions of surface temperatures, plasma conditions, and oblique angle of incidence of magnetic field to target surface will be discussed. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC-05-00OR22725.

  9. Displacement damage effects on CMOS APS image sensors induced by neutron irradiation from a nuclear reactor

    SciTech Connect

    Wang, Zujun Huang, Shaoyan; Liu, Minbo; Xiao, Zhigang; He, Baoping; Yao, Zhibin; Sheng, Jiangkun

    2014-07-15

    The experiments of displacement damage effects on CMOS APS image sensors induced by neutron irradiation from a nuclear reactor are presented. The CMOS APS image sensors are manufactured in the standard 0.35 μm CMOS technology. The flux of neutron beams was about 1.33 × 10{sup 8} n/cm{sup 2}s. The three samples were exposed by 1 MeV neutron equivalent-fluence of 1 × 10{sup 11}, 5 × 10{sup 11}, and 1 × 10{sup 12} n/cm{sup 2}, respectively. The mean dark signal (K{sub D}), dark signal spike, dark signal non-uniformity (DSNU), noise (V{sub N}), saturation output signal voltage (V{sub S}), and dynamic range (DR) versus neutron fluence are investigated. The degradation mechanisms of CMOS APS image sensors are analyzed. The mean dark signal increase due to neutron displacement damage appears to be proportional to displacement damage dose. The dark images from CMOS APS image sensors irradiated by neutrons are presented to investigate the generation of dark signal spike.

  10. Neutron irradiation effects on the microstructural development of tungsten and tungsten alloys

    NASA Astrophysics Data System (ADS)

    Hasegawa, Akira; Fukuda, Makoto; Yabuuchi, Kiyohiro; Nogami, Shuhei

    2016-04-01

    Data on the microstructural development of tungsten (W) and tungsten rhenium (Re) alloys were obtained after neutron irradiation at 400-800 °C in the Japan Materials Testing Reactor (JMTR), the experimental fast test reactor Joyo, and the High Flux Isotope Reactor (HFIR) for irradiation damage levels in the range of 0.09-1.54 displacement per atom (dpa). Microstructural observations showed that a small amount of Re (3-5%) in W-Re alloys is effective in suppressing void formation. In W-Re alloys with Re concentrations greater than 10%, acicular precipitates are the primary structural defects. In the HFIR-irradiated specimen, in which a large amount of Re was expected to be produced by the nuclear transmutation of W to Re because of the reactor's high thermal neutron flux, voids were not observed even in pure W. The synergistic effects of displacement damage and solid transmutation elements on microstructural development are discussed, and the microstructural development of tungsten materials utilized in fusion reactors is predicted.

  11. Dimensional isotropy of 6H and 3C SiC under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Snead, Lance L.; Katoh, Yutai; Koyanagi, Takaaki; Terrani, Kurt; Specht, Eliot D.

    2016-04-01

    This investigation experimentally determines the as-irradiated crystal axes dimensional change of the common polytypes of SiC considered for nuclear application. Single crystal α-SiC (6H), β-SiC (3C), CVD β-SiC, and single crystal Si have been neutron irradiated near 60 °C from 2 × 1023 to 2 × 1026 n/m2 (E > 0.1 MeV), or about 0.02-20 dpa, in order to study the effect of irradiation on bulk swelling and strain along independent crystalline axes. Single crystal, powder diffractometry and density measurement have been carried out. For all neutron doses where the samples remained crystalline all SiC materials demonstrated equivalent swelling behavior. Moreover the 6H-SiC expanded isotropically. The magnitude of the swelling followed a ∼0.77 power law against dose consistent with a microstructure evolution driven by single interstitial (carbon) mobility. Extraordinarily large ∼7.8% volume expansion in SiC was observed prior to amorphization. Above ∼0.9 × 1025 n/m2 (E > 0.1 MeV) all SiC materials became amorphous with an identical swelling: a 11.7% volume expansion, lowering the density to 2.84 g/cm3. The as-amorphized density was the same at the 2 × 1025 and 2 × 1026 n/m2 (E > 0.1 MeV) dose levels.

  12. Characterization of neutron calibration fields at the TINT's 50 Ci americium-241/beryllium neutron irradiator

    NASA Astrophysics Data System (ADS)

    Liamsuwan, T.; Channuie, J.; Ratanatongchai, W.

    2015-05-01

    Reliable measurement of neutron radiation is important for monitoring and protection in workplace where neutrons are present. Although Thailand has been familiar with applications of neutron sources and neutron beams for many decades, there is no calibration facility dedicated to neutron measuring devices available in the country. Recently, Thailand Institute of Nuclear Technology (TINT) has set up a multi-purpose irradiation facility equipped with a 50 Ci americium-241/beryllium neutron irradiator. The facility is planned to be used for research, nuclear analytical techniques and, among other applications, calibration of neutron measuring devices. In this work, the neutron calibration fields were investigated in terms of neutron energy spectra and dose equivalent rates using Monte Carlo simulations, an in-house developed neutron spectrometer and commercial survey meters. The characterized neutron fields can generate neutron dose equivalent rates ranging from 156 μSv/h to 3.5 mSv/h with nearly 100% of dose contributed by neutrons of energies larger than 0.01 MeV. The gamma contamination was less than 4.2-7.5% depending on the irradiation configuration. It is possible to use the described neutron fields for calibration test and routine quality assurance of neutron dose rate meters and passive dosemeters commonly used in radiation protection dosimetry.

  13. Re-weldability of neutron-irradiated stainless steels studied by multi-pass TIG welding

    NASA Astrophysics Data System (ADS)

    Nakata, K.; Oishi, M.; Koshiishi, M.; Hashimoto, T.; Anzai, H.; Saito, Y.; Kono, W.

    2002-12-01

    Weldability of neutron-irradiated stainless steel (SS) has been studied by multi-pass bead-on-plate and build-up tungsten inert gas (TIG) welding, simulating the repair-welding of reactor components. Specimens were submerged arc welding (SAW) joint of Type 304 SS containing 0.5 appm helium (1.8 appm in the SAW weld metal). Sound welding could be obtained by one- to three-pass welding on the plates at weld heat inputs less than 1 MJ/m in the irradiated 304 SS base metal. In the case of the build-up welding of a groove, no visible defects appeared in the specimen at a heat input as low as 0.4 MJ/m. However, build-up welding at a high heat input of 1 MJ/m was prone to weld cracking, owing to the formation of helium bubbles on grain boundaries of the base metal or dendrite boundaries of pre-existing SAW weld metal, in the area within 0.6 mm from the fusion line.

  14. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance L.

    2015-10-01

    The Fe-Cr-Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe-Cr-Al alloys has not been fully established. In this study, a series of Fe-Cr-Al alloys with 10-18 wt % Cr and 2.9-4.9 wt % Al were neutron irradiated at 382 °C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition. Dislocation loops with Burgers vector of a/2<111> and a<100> were detected and quantified. Results indicate precipitation of Cr-rich α‧ is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. A structure-property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α‧ precipitates at sufficiently high chromium contents after irradiation.

  15. Welding-induced mechanical properties in austenitic stainless steels before and after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Stoenescu, R.; Schäublin, R.; Gavillet, D.; Baluc, N.

    2007-03-01

    The effects of neutron irradiation on the mechanical properties of welded joints made of austenitic stainless steels have been investigated. The materials are welded AISI 304 and AISI 347, so-called test weld materials, irradiated with neutrons at 573 K to doses of 0.3 and 1.0 dpa. In addition, an AISI 304 from a decommissioned pressurised water reactor, so-called in-service material, which had accumulated a maximum dose of 0.35 dpa at about 573 K, was investigated. The mechanical properties of heat-affected zones and base materials were analysed before and after irradiation. Tensile parameters were determined at room temperature and at 573 K, for all materials and irradiation conditions. In the test weld materials it is found that radiation hardening is lower and loss of ductility is higher in the heat-affected zone than in the base material. In the in-service material radiation hardening is about the same in heat-affected zone and base material. After irradiation, deformation takes place by stacking faults and twins, at both room temperature and high temperature, contrary to unirradiated materials, where deformation takes place by twinning at room temperature and by dislocation cells at high temperature. No defect free channels are observed.

  16. Welding-induced microstructure in austenitic stainless steels before and after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Stoenescu, R.; Schäublin, R.; Gavillet, D.; Baluc, N.

    2007-02-01

    The effects of neutron irradiation on the microstructure of welded joints made of austenitic stainless steels have been investigated. The materials were welded AISI 304 and AISI 347, so-called test weld materials, and irradiated with neutrons at 300 °C to 0.3 and 1.0 dpa. In addition, an AISI 304 type from a decommissioned pressurised water reactor, so-called in-service material, which had accumulated a maximum dose of 0.35 dpa at about 300 °C, was investigated. The microstructure of heat-affected zones and base materials was analysed before and after irradiation, using transmission electron microscopy. Neutron diffraction was performed for internal stress measurements. It was found that the heat-affected zone contains, relative to the base material, a higher dislocation density, which relates well to a higher residual stress level and, after irradiation, a higher irradiation-induced defect density. In both materials, the irradiation-induced defects are of the same type, consisting in black dots and Frank dislocation loops. Careful analysis of the irradiation-induced defect contrast was performed and it is explained why no stacking fault tetrahedra could be identified.

  17. Startup of the Fission Converter Epithermal Neutron Irradiation Facility at the MIT Reactor

    SciTech Connect

    Newton, Thomas H. Jr.; Riley, Kent J.; Binns, Peter J.; Kohse, Gordon E.; Hu Linwen; Harling, Otto K.

    2002-08-15

    A new epithermal neutron irradiation facility, based on a fission converter assembly placed in the thermal column outside the reactor core, has been put into operation at the Massachusetts Institute of Technology Research Reactor (MITR). This facility was constructed to provide a high-intensity, forward-directed beam for use in neutron capture therapy with an epithermal flux of [approximately equal to]10{sup 10} n/cm{sup 2}.s at the medical room entrance with negligible fast neutron and gamma-ray contamination. The fission converter assembly consists of 10 or 11 MITR fuel elements placed in an aluminum tank and cooled with D{sub 2}O. Thermal-hydraulic criteria were established based on heat deposition calculations. Various startup tests were performed to verify expected neutronic and thermal-hydraulic behavior. Flow testing showed an almost flat flow distribution across the fuel elements with <5% bypass flow. The total reactivity change caused by operation of the facility was measured at 0.014 {+-} 0.002% {delta}K/K. Thermal power produced by the facility was measured to be 83.1 {+-} 4.2 kW. All of these test results satisfied the thermal-hydraulic safety criteria. In addition, radiation shielding design measurements were made that verified design calculations for the neutronic performance.

  18. Irradiation temperature dependence of production efficiency of lattice defects in some neutron-irradiated oxides

    NASA Astrophysics Data System (ADS)

    Okada, Moritami; Atobe, Kozo; Nakagawa, Masuo

    2004-11-01

    Temperature dependence of production efficiency of irradiation-induced defects in neutron-irradiated oxides has been investigated. Some oxide single crystals, MgO, α-Al2O3 (sapphire) and TiO2 (rutile), were irradiated at several controlled temperatures, 10, 20, 50, 100, 150 and 200 K, using the low-temperature irradiation facility of Kyoto University Reactor (KUR-LTL), and at ambient temperature (∼370 K) in the same facility. Irradiation temperature dependence of production efficiency of a 1 μm band in TiO2 differs greatly from that of anion vacancy (F-type centers) in MgO and α-Al2O3. Results for MgO and α-Al2O3 show steep negative gradients from 10 to 370 K, whereas that for TiO2 includes a valley between 40 and 60 K and a hump at about 130 K, and then disappear at about 200 K. In MgO and α-Al2O3, this behavior can be explained by the recombination of Frenkel pairs, which is activated at higher temperature. In TiO2, in addition to the recombination mechanism, a covalent bonding property is thought to be exerted strong influence, and it is suggested that a disappearance of the 1 μm band at above 200 K is due to the recombination process of Frenkel pairs which is caused by the irradiation-induced crystallization.

  19. Resistivity recovery in high purity iron after fission- and fusion- neutron irradiation*1

    NASA Astrophysics Data System (ADS)

    Matsui, H.; Takehana, S.; Guinan, M. W.

    1988-07-01

    A resistometric study of high-purity iron has been performed after irradiation at 20 K by 14 MeV neutrons in RTNS-II or by fission neutrons in Kyoto University Reactor (KUR). The annealing behavior of iron after fusion neutrons is very different from that after electron irradiation. The fractional recovery in stage I is much smaller and the recovery of vacancy type defects starts to occur at a much lower temperature with a lower activation energy than after electron iradiation. The difference between fission and fusion neutron irradiation, however, is much smaller; the isochronal curves for these two types of irradiation are essentially the same below 170 K. It is concluded that the local defect configuration for these two types of irradiation is similar. The induced resistivity by fusion neutrons is about a factor of 2 larger than by fission neutrons (fluence for E > 1 MeV). This is in accord with a rough estimation of the ratio of damage energy cross sections.

  20. Deformation localization and dislocation channel dynamics in neutron-irradiated austenitic stainless steels

    DOE PAGESBeta

    Gussev, Maxim N.; Field, Kevin G.; Busby, Jeremy T.

    2015-02-24

    We investigated dynamics of deformation localization and dislocation channel formation in situ in a neutron irradiated AISI 304 austenitic stainless steel and a model 304-based austenitic alloy by combining several analytical techniques including optic microscopy and laser confocal microscopy, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Channel formation was observed at 70% of the formal tensile yield stress for both alloys. It was shown that triple junction points do not always serve as a source of dislocation channels; at stress levels below the yield stress, channels often formed near the middle of the grain boundary. For amore » single grain, the role of elastic stiffness value (Young modulus) in the channel formation was analyzed; it was shown that in the irradiated 304 steels the initial channels appeared in soft grains with a high Schmid factor located near stiff grains with high elastic stiffness. Moreover, the spatial organization of channels in a single grain was analyzed; it was shown that secondary channels operating in the same slip plane as primary channels often appeared at the middle or at one third of the way between primary channels. The twinning nature of dislocation channels was analyzed for grains of different orientation using TEM. Finally, it was shown that in the AISI 304 steel, channels were twin-free in grains oriented close to [001] and [101] of standard unit triangle; [111]-grains and grains oriented close to Schmid factor maximum contained deformation twins.« less

  1. Filtered fast neutron irradiation system using Texas A&M University Nuclear Science Center Reactor

    NASA Astrophysics Data System (ADS)

    Jang, S. Y.; Kim, C. H.; Reece, W. D.; Braby, L. A.

    2004-09-01

    A heavily filtered fast neutron irradiation system (FNIS) was developed for a variety of applications, including the study of long-term health effects of fast neutrons by evaluating the biological mechanisms of damage in cultured cells and living animals such as rats or mice. This irradiation system includes an exposure cave made with a lead-bismuth alloy, a cave positioning system, a gamma and neutron monitoring system, a sample transfer system, and interchangeable filters. This system was installed in the irradiation cell of the Texas A&M University Nuclear Science Center Reactor (NSCR). For a realistic modeling of the NSCR, the irradiation cell, and the FNIS, this study used the Monte Carlo N-Particle (MCNP) code and a set of high-temperature ENDF/B-VI continuous neutron cross-section data. Sensitivity analysis was performed to find the characteristics of the FNIS as a function of the thickness of the lead-bismuth alloy. A paired ion chamber system was constructed with a tissue-equivalent plastic (A-150) and propane gas for total dose monitoring and with graphite and argon for gamma dose monitoring. This study, in addition, tested the Monte Carlo modeling of the FNIS system, as well as the performance of the system by comparing the calculated results with experimental measurements using activation foils and paired ion chambers.

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

    SciTech Connect

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

    1999-07-01

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

  3. Irradiation effect on deuterium behaviour in low-dose HFIR neutron-irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Shimada, Masashi; Cao, G.; Otsuka, T.; Hara, M.; Kobayashi, M.; Oya, Y.; Hatano, Y.

    2015-01-01

    Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor (HFIR), Oak Ridge National Laboratory at reactor coolant temperatures of 50-70 °C to low displacement damage of 0.025 and 0.3 dpa. After cooling down, the HFIR neutron-irradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 °C twice at the ion fluence of 5 × 1025 m-2 to reach the total ion fluence of 1 × 1026 m-2 in order to investigate the near-surface deuterium retention and saturation via nuclear reaction analysis. Final thermal desorption spectroscopy was performed to elucidate the irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near-surface (<5 µm depth) deuterium concentration increased from 0.5 at% D/W in 0.025 dpa samples to 0.8 at% D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the near-surface retention via nuclear reaction analysis indicated the deuterium was trapped in bulk (at least 50 µm depth for 0.025 dpa and 35 µm depth for 0.3 dpa) at 500 °C cases even in the relatively low ion fluence of 1026 m-2.

  4. PGNAA system preliminary design and measurement of In-Hospital Neutron Irradiator for boron concentration measurement.

    PubMed

    Zhang, Zizhu; Chong, Yizheng; Chen, Xinru; Jin, Congjun; Yang, Lijun; Liu, Tong

    2015-12-01

    A prompt gamma neutron activation analysis (PGNAA) system has been recently developed at the 30-kW research reactor In-Hospital Neutron Irradiator (IHNI) in Beijing. Neutrons from the specially designed thermal neutron beam were used. The thermal flux of this beam is 3.08×10(6) cm(-2) s(-1) at a full reactor power of 30 kW. The PGNAA system consists of an n-type high-purity germanium (HPGe) detector of 40% efficiency, a digital spectrometer, and a shielding part. For both the detector shielding part and the neutron beam shielding part, the inner layer is composed of (6)Li2CO3 powder and the outer layer lead. The boron-10 sensitivity of the PGNAA system is approximately 2.5 cps/ppm. Two calibration curves were produced for the 1-10 ppm and 10-50 ppm samples. The measurement results of the control samples were in accordance with the inductively coupled plasma atomic emission spectroscopy (ICP-AES) results.

  5. Development of positron annihilation spectroscopy for investigating deuterium decorated voids in neutron-irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Taylor, C. N.; Shimada, M.; Merrill, B. J.; Akers, D. W.; Hatano, Y.

    2015-08-01

    The present work is a continuation of a recent research to develop and optimize positron annihilation spectroscopy (PAS) for characterizing neutron-irradiated tungsten. Tungsten samples were exposed to neutrons in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory and damaged to 0.025 and 0.3 dpa. Subsequently, they were exposed to deuterium plasmas in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory. The implanted deuterium was desorbed through sample heating to 900 °C, and Doppler broadening (DB)-PAS was performed both before and after heating. Results show that deuterium impregnated tungsten is identified as having a smaller S-parameter. The S-parameter increases after deuterium desorption. Microstructural changes also occur during sample heating. These effects can be isolated from deuterium desorption by comparing the S-parameters from the deuterium-free back face with the deuterium-implanted front face. The application of using DB-PAS to examine deuterium retention in tungsten is examined.

  6. Deformation localization and dislocation channel dynamics in neutron-irradiated austenitic stainless steels

    SciTech Connect

    Gussev, Maxim N.; Field, Kevin G.; Busby, Jeremy T.

    2015-02-24

    We investigated dynamics of deformation localization and dislocation channel formation in situ in a neutron irradiated AISI 304 austenitic stainless steel and a model 304-based austenitic alloy by combining several analytical techniques including optic microscopy and laser confocal microscopy, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Channel formation was observed at 70% of the formal tensile yield stress for both alloys. It was shown that triple junction points do not always serve as a source of dislocation channels; at stress levels below the yield stress, channels often formed near the middle of the grain boundary. For a single grain, the role of elastic stiffness value (Young modulus) in the channel formation was analyzed; it was shown that in the irradiated 304 steels the initial channels appeared in soft grains with a high Schmid factor located near stiff grains with high elastic stiffness. Moreover, the spatial organization of channels in a single grain was analyzed; it was shown that secondary channels operating in the same slip plane as primary channels often appeared at the middle or at one third of the way between primary channels. The twinning nature of dislocation channels was analyzed for grains of different orientation using TEM. Finally, it was shown that in the AISI 304 steel, channels were twin-free in grains oriented close to [001] and [101] of standard unit triangle; [111]-grains and grains oriented close to Schmid factor maximum contained deformation twins.

  7. Neutron-irradiation creep of silicon carbide materials beyond the initial transient

    DOE PAGESBeta

    Katoh, Yutai; Ozawa, Kazumi; Shimoda, Kazuya; Hinoki, Tatsuya; Snead, Lance Lewis; Koyanagi, Takaaki

    2016-06-04

    Irradiation creep beyond the transient regime was investigated for various silicon carbide (SiC) materials. Here, the materials examined included polycrystalline or monocrystalline high-purity SiC, nanopowder sintered SiC, highly crystalline and near-stoichiometric SiC fibers (including Hi-Nicalon Type S, Tyranno SA3, isotopically-controlled Sylramic and Sylramic-iBN fibers), and a Tyranno SA3 fiber–reinforced SiC matrix composite fabricated through a nano-infiltration transient eutectic phase process. Neutron irradiation experiments for bend stress relaxation tests were conducted at irradiation temperatures ranging from 430 to 1180 °C up to 30 dpa with initial bend stresses of up to ~1 GPa for the fibers and ~300 MPa for themore » other materials. Initial bend stress in the specimens continued to decrease from 1 to 30 dpa. Analysis revealed that (1) the stress exponent of irradiation creep above 1 dpa is approximately unity, (2) the stress normalized creep rate is ~1 × 10–7 [dpa–1 MPa–1] at 430–750 °C for the range of 1–30 dpa for most polycrystalline SiC materials, and (3) the effects on irradiation creep of initial microstructures—such as grain boundary, crystal orientation, and secondary phases—increase with increasing irradiation temperature.« less

  8. Neutron flux assessment of a neutron irradiation facility based on inertial electrostatic confinement fusion.

    PubMed

    Sztejnberg Gonçalves-Carralves, M L; Miller, M E

    2015-12-01

    Neutron generators based on inertial electrostatic confinement fusion were considered for the design of a neutron irradiation facility for explanted organ Boron Neutron Capture Therapy (BNCT) that could be installed in a health care center as well as in research areas. The chosen facility configuration is "irradiation chamber", a ~20×20×40 cm(3) cavity near or in the center of the facility geometry where samples to be irradiated can be placed. Neutron flux calculations were performed to study different manners for improving scattering processes and, consequently, optimize neutron flux in the irradiation position. Flux distributions were assessed through numerical simulations of several models implemented in MCNP5 particle transport code. Simulation results provided a wide spectrum of combinations of net fluxes and energy spectrum distributions. Among them one can find a group that can provide thermal neutron fluxes per unit of production rate in a range from 4.1·10(-4) cm(-2) to 1.6·10(-3) cm(-2) with epithermal-to-thermal ratios between 0.3% and 13% and fast-to-thermal ratios between 0.01% to 8%. Neutron generators could be built to provide more than 10(10) n s(-1) and, consequently, with an arrangement of several generators appropriate enough neutron fluxes could be obtained that would be useful for several BNCT-related irradiations and, eventually, for clinical practice.

  9. Strain hardening and plastic instability properties of austenitic stainless steels after proton and neutron irradiation

    NASA Astrophysics Data System (ADS)

    Byun, T. S.; Farrell, K.; Lee, E. H.; Hunn, J. D.; Mansur, L. K.

    2001-10-01

    Strain hardening and plastic instability properties were analyzed for EC316LN, HTUPS316, and AL6XN austenitic stainless steels after combined 800 MeV proton and spallation neutron irradiation to doses up to 10.7 dpa. The steels retained good strain-hardening rates after irradiation, which resulted in significant uniform strains. It was found that the instability stress, the stress at the onset of necking, had little dependence on the irradiation dose. Tensile fracture stress and strain were calculated from the stress-strain curve data and were used to estimate fracture toughness using an existing model. The doses to plastic instability and fracture, the accumulated doses at which the yield stress reaches instability stress or fracture stress, were predicted by extrapolation of the yield stress, instability stress, and fracture stress to higher dose. The EC316LN alloy required the highest doses for plastic instability and fracture. Plastic deformation mechanisms are discussed in relation to the strain-hardening properties of the austenitic stainless steels.

  10. Flux dependence of cluster formation in neutron-irradiated weld material

    NASA Astrophysics Data System (ADS)

    Bergner, F.; Ulbricht, A.; Hein, H.; Kammel, M.

    2008-03-01

    The effect of neutron flux on the formation of irradiation-induced clusters in reactor pressure vessel (RPV) steels is an unresolved issue. Small-angle neutron scattering was measured for a neutron-irradiated RPV weld material containing 0.22 wt% impurity Cu. The experiment was focused on the influence of neutron flux on the formation of irradiation-induced clusters at fixed fluence. The aim was to separate and tentatively interpret the effect of flux on the characteristics of the cluster size distribution. We have observed a pronounced effect of neutron flux on cluster size, whereas the total volume fraction of irradiation-induced clusters is insensitive to the level of flux. The result is compatible with a rate theory model according to which the range of applied fluxes covers the transition from a flux-independent regime at lower fluxes to a regime of decelerating cluster growth. The results are confronted with measured irradiation-induced changes of mechanical properties. Despite the observed flux effect on cluster size, both yield stress increase and transition temperature shift turned out to be independent of flux. This is in agreement with the volume fraction of irradiation-induced clusters being insensitive to the level of flux.

  11. Effect of neutron irradiation on charge collection efficiency in 4H-SiC Schottky diode

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Jiang, Yong; Lei, Jiarong; Fan, Xiaoqiang; Chen, Yu; Li, Meng; Zou, Dehui; Liu, Bo

    2014-01-01

    The charge collection efficiency (CCE) in 4H-SiC Schottky diode is studied as a function of neutron fluence. The 4H-SiC diode was irradiated with fast neutrons of a critical assembly in Nuclear Physics and Chemistry Institute and CCE for 3.5 MeV alpha particles was then measured as a function of the applied reverse bias. It was found from our experiment that an increase of neutron fluence led to a decrease of CCE. In particular, CCE of the diode was less than 1.3% at zero bias after an irradiation at 8.26×1014 n/cm2. A generalized Hecht's equation was employed to analyze CCE in neutron irradiated 4H-SiC diode. The calculations nicely fit the CCE of 4H-SiC diode irradiated at different neutron fluences. According to the calculated results, the extracted electron μτ product (μτ)e and hole μτ product (μτ)h of the irradiated 4H-SiC diode are found to decrease by increasing the neutron fluence.

  12. Tribocorrosion behavior of CoCrMo alloy for hip prosthesis as a function of loads: a comparison between two testing systems

    PubMed Central

    Mathew, M.T.; Runa, M.J.; Laurent, M.; Jacobs, J.J.; Rocha, L.A.; Wimmer, M.A.

    2011-01-01

    Metal-on-metal (MOM) hip prosthesis bearings have enjoyed renewed popularity, but concerns remain with wear debris and metal ion release causing a negative response in the surrounding tissues. Further understanding into the wear and corrosion mechanisms occurring in MOM hips is therefore essential. The purpose of this study was to evaluate the tribocorrosion behaviour, or interplay between corrosion and wear, of a low-carbon CoCrMo alloy as a function of loading. The tribocorrosion tests were performed using two tribometer configurations. In the first configuration, “System A”, a linearly reciprocating alumina ball slid against the flat metal immersed in a phosphate buffer solution (PBS). In the second configuration, “System B”, the flat end of a cylindrical metal pin was pressed against an alumina ball that oscillated rotationally, using bovine calf serum (BCS) as the lubricant and electrolyte. System B was custom-built to emulate in vivo conditions. The tribocorrosion tests were performed under potentiostatic conditions at -0.345V, with a sliding duration of 1800 seconds and a frequency of 1Hz. In System A the applied loads were 0.05, 0.5, and 1N (138, 296 and 373MPa, respectively) and in System B were 16, 32, and 64N (474, 597, and 752MPa, respectively). Electrochemical impedance spectroscopy (EIS) and polarization resistance were estimated. The total mass loss (Kwc) in the CoCrMo was determined. The mass loss due to wear (Kw) and that due to corrosion (Kc) were determined. The dominant wear regime for the CoCrMo alloy subjected to sliding changes from wear-corrosion to mechanical wear as the contact stress increases. An attempt was made to compare both system, in their tribochemical responses and formulate some insights in the total degradation processes. Our results also suggest that the proteins in the serum lubricant assist in the generation of a protective layer against corrosion during sliding. The study highlights the need of adequate methodology

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

    NASA Astrophysics Data System (ADS)

    Nagai, Akiko; Tsutsumi, Yusuke; Suzuki, Yuta; Katayama, Keiichi; Hanawa, Takao; Yamashita, Kimihiro

    2012-05-01

    The air-formed surface oxide films used for stents were characterized to determine their composition and chemical state on a Co-Ni-Cr-Mo alloy. The change of the films in Hanks' solution was used to estimate the reconstruction of the film in the human body. Angle-resolved X-ray photoelectron spectroscopy was used to characterize the composition of the film and substrate, as well as the film's thickness. The surface oxide film on the Co-Ni-Cr-Mo alloy (when mechanically polished) consists of oxide species of cobalt, nickel, chromium, and molybdenum, contains a large amount of OH-, and has a thickness of approximately 2.5 nm. Cations exist in the oxide as Co2+, Ni2+, Cr3+, Mo4+, Mo5+, and Mo6+. Chromium is enriched and cobalt and nickel are depleted in the oxide; however, nickel is enriched and cobalt is depleted in the substrate alloy just under the surface oxide film. Concentration of chromium was low and that of nickel was high at small take-off angles. This indicates that distribution of chromium is greater in the inner layer, but nickel is distributed more in the outer layer of the surface oxide film. During immersion in Hanks' solution, cobalt and nickel dissolved, and the film composition changed to mostly chromium oxide (Cr3+), along with small amounts of cobalt, nickel, and molybdenum oxides, and calcium phosphate containing magnesium, potassium, and carbonate. After immersion in Hanks' solution, the thickness of the surface layer containing calcium phosphate increased to more than 4 nm, while the amount of OH- increased. The amount of cobalt and nickel in the surface oxide film and in the substrate alloy just below the oxide decreased during immersion.

  14. Effect of carbon on the microstructure, mechanical properties and metal ion release of Ni-free Co-Cr-Mo alloys containing nitrogen.

    PubMed

    Mori, Manami; Yamanaka, Kenta; Kuramoto, Koji; Ohmura, Kazuyo; Ashino, Tetsuya; Chiba, Akihiko

    2015-10-01

    This paper investigated the effect of carbon addition on the microstructure and tensile properties of Ni-free biomedical Co-29Cr-6Mo (mass%) alloys containing 0.2 mass% nitrogen. The release of metal ions by the alloys was preliminarily evaluated in an aqueous solution of 0.6% sodium chloride (NaCl) and 1% lactic acid, after which samples with different carbon contents were subjected to hot rolling. All specimens were found to primarily consist of a γ-phase matrix due to nitrogen doping, with only the volume fraction of M23C6 increasing with carbon concentration. Owing to the very fine size of these carbide particles (less than 1 μm), which results from fragmentation during hot rolling, the increased formation of M23C6 increased the 0.2% proof stress, but reduced the elongation-to-failure. Carbon addition also increased the amount of Co and Cr released during static immersion; Co and Cr concentrations at the surfaces, which increased with increasing the bulk carbon concentrations, possibly enhanced the metal ion release. However, only a very small change in the Mo concentration was noticed in the solution. Therefore, it is not necessarily considered a suitable means of improving the strength of biomedical Co-Cr-Mo alloys, even though it has only to date been used in this alloy system. The results of this study revealed the limitations of the carbon strengthening and can aid in the design of biomedical Co-Cr-Mo-based alloys that exhibit the high durability needed for their practical application.

  15. Study of the VMM1 read-out chip in a neutron irradiation environment

    NASA Astrophysics Data System (ADS)

    Alexopoulos, T.; Fanourakis, G.; Geralis, T.; Kokkoris, M.; Kourkoumeli-Charalampidi, A.; Papageorgiou, K.; Tsipolitis, G.

    2016-05-01

    Within 2015, the LHC operated close to the design energy of √s = 13-14 TeV delivering instantaneous luminosities up to Script L = 5 × 1033 cm-2s-1. The ATLAS Phase-I upgrade in 2018/19 will introduce the MicroMEGAS detectors in the area of the small wheel at the end caps. Accompanying new electronics are designed and built such as the VMM front end ASIC, which provides energy, timing and triggering information and allows fast data read-out. The first VMM version (VMM1) has been widely produced and tested in various test beams, whilst the second version (VMM2) is currently being tested. This paper focuses on the VMM1 single event upset studies and more specifically on the response of the configuration registers under harsh radiation environments. Similar conditions are expected at Run III with Script L = 2 × 1034 cm-2s-1 and a mean of 55 interactions per bunch crossing. Two VMM1s were exposed in a neutron irradiation environment using the TANDEM Van Der Graaff accelerator at NSCR Demokritos, Athens, Greece. The results showed a rate of SEU occurrences at a measured cross section of (4.1±0.8)×10-14 cm2/bit for each VMM. Consequently, when extrapolating this value to the luminosity expected in Run III, the occurrence is roughly 6 SEUs/min in all the read-out system comprising 40,000 VMMs installed during the Phase-I upgrade.

  16. Irradiation effect on deuterium behaviour in low-dose HFIR neutron-irradiated tungsten

    SciTech Connect

    Shimada, Masashi; Cao, G.; Otsuka, T.; Hara, M.; Kobayashi, M.; Oya, Y.; Hatano, Y.

    2014-12-01

    Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor, Oak Ridge National Laboratory at reactor coolant temperatures of 50-70°C to low displacement damage of 0.025 and 0.3 dpa under the framework of the US-Japan TITAN program (2007-2013). After cooling down, the HFIR neutron-irradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 °C twice at the ion fluence of 5×10²⁵ m⁻² to reach a total ion fluence of 1×10²⁶ m⁻² in order to investigate the near surface deuterium retention and saturation via nuclear reaction analysis. Final thermal desorption spectroscopy was performed to elucidate irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near surface (<5 µm depth) deuterium concentration increased from 0.5 at % D/W in 0.025 dpa samples to 0.8 at. % D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the near surface retention via nuclear reaction analysis indicated the deuterium was migrated and trapped in bulk (at least 50 µm depth for 0.025 dpa and 35 µm depth for 0.025 dpa) at 500 °C case even in the relatively low ion fluence of 10²⁶ m⁻².

  17. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    DOE PAGESBeta

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Wirth, Brian D; Snead, Lance Lewis

    2016-01-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (~90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutronmore » irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S–W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage. This provides insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.« less

  18. The role of dislocation channeling in IASCC initiation of neutron irradiated austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Stephenson, Kale Jennings

    The objective of this study was to understand the role of dislocation channeling in the initiation of irradiation-assisted stress corrosion cracking (IASCC) of neutron irradiated austenitic stainless steel using a novel four-point bend test. Stainless steels used in this study were irradiated in the BOR-60 fast reactor at 320 °C, and included a commercial purity 304L stainless steel irradiated to 5.5, 10.2, and 47.5 dpa, and two high purity stainless steels, Fe-18Cr-12Ni and Fe-18Cr-25Ni, irradiated to ~10 dpa. The four-point bend test produced the same relative IASCC susceptibility as constant extension rate tensile (CERT) experiments performed on the same irradiated alloys in boiling water reactor normal water chemistry. The cracking susceptibility of the CP 304L alloy was high at all irradiation dose levels, enhanced by the presence of MnS inclusions in the alloy microstructure, which dissolve in the NWC environment. Dissolution of the MnS inclusion results in formation of an oxide cap that occludes the inclusion site, creating a crevice condition with a high propensity for crack initiation. Crack initiation at these locations was induced by stress concentration at the intersecting grain boundary, resulting from the intersection of a discontinuous dislocation channels (DC). Stress to initiate an IASCC crack decreased with dose due earlier DC initiation. The HP Fe-18Cr-12Ni alloy had low susceptibility to IASCC, while the high Ni alloy exhibited no cracking susceptibility. The difference in susceptibility among these conditions was attributed to the propensity for DCs to transmit across grain boundaries, which controls stress accumulation at DC -- grain boundary intersections.

  19. Study of the VMM1 read-out chip in a neutron irradiation environment

    NASA Astrophysics Data System (ADS)

    Alexopoulos, T.; Fanourakis, G.; Geralis, T.; Kokkoris, M.; Kourkoumeli-Charalampidi, A.; Papageorgiou, K.; Tsipolitis, G.

    2016-05-01

    Within 2015, the LHC operated close to the design energy of √s = 13–14 TeV delivering instantaneous luminosities up to Script L = 5 × 1033 cm‑2s‑1. The ATLAS Phase-I upgrade in 2018/19 will introduce the MicroMEGAS detectors in the area of the small wheel at the end caps. Accompanying new electronics are designed and built such as the VMM front end ASIC, which provides energy, timing and triggering information and allows fast data read-out. The first VMM version (VMM1) has been widely produced and tested in various test beams, whilst the second version (VMM2) is currently being tested. This paper focuses on the VMM1 single event upset studies and more specifically on the response of the configuration registers under harsh radiation environments. Similar conditions are expected at Run III with Script L = 2 × 1034 cm‑2s‑1 and a mean of 55 interactions per bunch crossing. Two VMM1s were exposed in a neutron irradiation environment using the TANDEM Van Der Graaff accelerator at NSCR Demokritos, Athens, Greece. The results showed a rate of SEU occurrences at a measured cross section of (4.1±0.8)×10‑14 cm2/bit for each VMM. Consequently, when extrapolating this value to the luminosity expected in Run III, the occurrence is roughly 6 SEUs/min in all the read-out system comprising 40,000 VMMs installed during the Phase-I upgrade.

  20. Comparison of properties and microstructures of Trefimetaux and Hycon 3HP{trademark} after neutron irradiation

    SciTech Connect

    Edwards, D.J.; Singh, B.N.; Toft, P.; Eldrup, M.

    1998-09-01

    The precipitation strengthened CuNiBe alloys are among three candidate copper alloys being evaluated for application in the first wall, divertor, and limiter components of ITER. Generally, CuNiBe alloys have higher strength but poorer conductivity compared to CuCrZr and CuAl{sub 2}O{sub 3} alloys. Brush-Wellman Inc. has manufactured an improved version of their Hycon CuNiBe alloy that has higher conductivity while maintaining a reasonable level strength. It is of interest, therefore, to investigate the effect of radiation on the physical and mechanical properties of this alloy. In the present work the authors have investigated the physical and mechanical properties of the Hycon 3HP{trademark} alloy both before and after neutron irradiation and have compared its microstructure and properties with the European CuNiBe candidate alloy manufactured by Trefirmetaux. Tensile specimens of both alloys were irradiated in the DR-3 reactor at Risoe to displacement dose levels up to 0.3 dpa at 100, 250 and 350 C. Both alloys were tensile tested in the unirradiated and irradiated conditions at 100, 250 and 350 C. Both pre- and post-irradiation microstructures of the alloys were investigated in detail using transmission electron microscopy. Fracture surfaces were examined under a scanning electron microscope. Electrical resistivity measurements were made on tensile specimens before and after irradiation; all measurements were made at 23 C. At this point it seems unlikely that CuNiBe alloys can be recommended for applications in neutron environments where the irradiation temperature exceeds 200 C. Applications at temperatures below 200 C might be plausible, but only after careful experiments have determined the dose dependence of the mechanical properties and the effect of sudden temperature excursions on the material to establish the limits on the use of the alloy.

  1. Irradiation effect on deuterium behaviour in low-dose HFIR neutron-irradiated tungsten

    DOE PAGESBeta

    Shimada, Masashi; Cao, G.; Otsuka, T.; Hara, M.; Kobayashi, M.; Oya, Y.; Hatano, Y.

    2014-12-01

    Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor, Oak Ridge National Laboratory at reactor coolant temperatures of 50-70°C to low displacement damage of 0.025 and 0.3 dpa under the framework of the US-Japan TITAN program (2007-2013). After cooling down, the HFIR neutron-irradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 °C twice at the ion fluence of 5×10²⁵ m⁻² to reach a total ion fluence of 1×10²⁶ m⁻² in order to investigate the near surface deuterium retention and saturation via nuclear reaction analysis. Finalmore » thermal desorption spectroscopy was performed to elucidate irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near surface (<5 µm depth) deuterium concentration increased from 0.5 at % D/W in 0.025 dpa samples to 0.8 at. % D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the near surface retention via nuclear reaction analysis indicated the deuterium was migrated and trapped in bulk (at least 50 µm depth for 0.025 dpa and 35 µm depth for 0.025 dpa) at 500 °C case even in the relatively low ion fluence of 10²⁶ m⁻².« less

  2. Modeling of displacement damage in silicon carbide detectors resulting from neutron irradiation

    NASA Astrophysics Data System (ADS)

    Khorsandi, Behrooz

    There is considerable interest in developing a power monitor system for Generation IV reactors (for instance GT-MHR). A new type of semiconductor radiation detector is under development based on silicon carbide (SiC) technology for these reactors. SiC has been selected as the semiconductor material due to its superior thermal-electrical-neutronic properties. Compared to Si, SiC is a radiation hard material; however, like Si, the properties of SiC are changed by irradiation by a large fluence of energetic neutrons, as a consequence of displacement damage, and that irradiation decreases the life-time of detectors. Predictions of displacement damage and the concomitant radiation effects are important for deciding where the SiC detectors should be placed. The purpose of this dissertation is to develop computer simulation methods to estimate the number of various defects created in SiC detectors, because of neutron irradiation, and predict at what positions of a reactor, SiC detectors could monitor the neutron flux with high reliability. The simulation modeling includes several well-known---and commercial---codes (MCNP5, TRIM, MARLOWE and VASP), and two kinetic Monte Carlo codes written by the author (MCASIC and DCRSIC). My dissertation will highlight the displacement damage that may happen in SiC detectors located in available positions in the OSURR, GT-MHR and IRIS. As extra modeling output data, the count rates of SiC for the specified locations are calculated. A conclusion of this thesis is SiC detectors that are placed in the thermal neutron region of a graphite moderator-reflector reactor have a chance to survive at least one reactor refueling cycle, while their count rates are acceptably high.

  3. Dimensional isotropy of 6H and 3C SiC under neutron irradiation

    DOE PAGESBeta

    Snead, Lance L.; Katoh, Yutai; Koyanagi, Takaaki; Terrani, Kurt A.; Specht, Eliot D.

    2016-01-16

    This investigation experimentally determines the as-irradiated crystal axes dimensional change of the common polytypes of SiC considered for nuclear application. Single crystal α-SiC (6H), β-SiC (3C), CVD β-SiC, and single crystal Si have been neutron irradiated near 60 °C from 2 × 1023 to 2 × 1026 n/m2 (E > 0.1 MeV), or about 0.02–20 dpa, in order to study the effect of irradiation on bulk swelling and strain along independent crystalline axes. Single crystal, powder diffractometry and density measurement have been carried out. For all neutron doses where the samples remained crystalline all SiC materials demonstrated equivalent swelling behavior.more » Moreover the 6H–SiC expanded isotropically. The magnitude of the swelling followed a ~0.77 power law against dose consistent with a microstructure evolution driven by single interstitial (carbon) mobility. Extraordinarily large ~7.8% volume expansion in SiC was observed prior to amorphization. Above ~0.9 × 1025 n/m2 (E > 0.1 MeV) all SiC materials became amorphous with an identical swelling: a 11.7% volume expansion, lowering the density to 2.84 g/cm3. As a result, the as-amorphized density was the same at the 2 × 1025 and 2 × 1026 n/m2 (E > 0.1 MeV) dose levels.« less

  4. Effects of thermal aging and neutron irradiation on the mechanical properties of stainless steel weld overlay cladding

    SciTech Connect

    Haggag, F.M.; Nanstad, R.K.

    1991-01-01

    Stainless steel weld overlay cladding was fabricated using the three-wire, series-arc method. Three layers of cladding were applied to a pressure vessel plate to provide adequate thickness for fabrication of test specimens. Since irradiation of the stainless steel cladding to 5 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV) was conducted at 288{degrees}C for 1605 h, tensile, Charpy V-notch (CVN), precracked Charpy V-notch (PCVN), and compact fracture toughness specimens were thermally aged at 288{degrees}C for 1605 h. Additional specimens are being aged to 20,000 and 50,000 h. Thermal aging of three-wire, series-arc stainless steel weld overlay cladding at 288{degrees}C for 1604 h resulted in appreciable decrease (16%) in the CVN upper-shelf energy, but the effect on the 41-J transition temperature shift was very small (3{degrees}C). The combined effect, following neutron irradiation at 288{degrees}C to a fluence of 5 {times} 10{sup 19} neutrons/cm{sup 2} (>MeV), was a 22% reduction in the CVN upper-shelf energy and a 29{degrees}C shift at the 41-J level. The effect of thermal aging on tensile properties was very small or negligible. However, the combined effect after neutron irradiation was an increase in the yield strength (6 to 34% at test temperatures from 288 to {minus}125{degrees}C) and no apparent change in ultimate strength and total elongation. Also, neutron irradiation reduced the initiation fracture toughness (J{sub Ic}) much more than did thermal aging. However, irradiation slightly decreased the tearing modulus, but no reduction was caused by thermal aging alone. The effects of long-term thermal exposure times (20,000 and 50,000 h) will be investigated when the specimen become available.

  5. Effects of thermal aging and neutron irradiation on the mechanical properties of stainless steel weld overlay cladding

    SciTech Connect

    Haggag, F.M.; Nanstad, R.K.

    1991-12-31

    Stainless steel weld overlay cladding was fabricated using the three-wire, series-arc method. Three layers of cladding were applied to a pressure vessel plate to provide adequate thickness for fabrication of test specimens. Since irradiation of the stainless steel cladding to 5 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV) was conducted at 288{degrees}C for 1605 h, tensile, Charpy V-notch (CVN), precracked Charpy V-notch (PCVN), and compact fracture toughness specimens were thermally aged at 288{degrees}C for 1605 h. Additional specimens are being aged to 20,000 and 50,000 h. Thermal aging of three-wire, series-arc stainless steel weld overlay cladding at 288{degrees}C for 1604 h resulted in appreciable decrease (16%) in the CVN upper-shelf energy, but the effect on the 41-J transition temperature shift was very small (3{degrees}C). The combined effect, following neutron irradiation at 288{degrees}C to a fluence of 5 {times} 10{sup 19} neutrons/cm{sup 2} (>MeV), was a 22% reduction in the CVN upper-shelf energy and a 29{degrees}C shift at the 41-J level. The effect of thermal aging on tensile properties was very small or negligible. However, the combined effect after neutron irradiation was an increase in the yield strength (6 to 34% at test temperatures from 288 to {minus}125{degrees}C) and no apparent change in ultimate strength and total elongation. Also, neutron irradiation reduced the initiation fracture toughness (J{sub Ic}) much more than did thermal aging. However, irradiation slightly decreased the tearing modulus, but no reduction was caused by thermal aging alone. The effects of long-term thermal exposure times (20,000 and 50,000 h) will be investigated when the specimen become available.

  6. Mechanical behavior of AISI 304SS determined by miniature test methods after neutron irradiation to 28 dpa

    SciTech Connect

    Ellen M. Rabenberg; Brian J. Jaques; Bulent H. Sencer; Frank A. Garner; Paula D. Freyer; Taira Okita; Darryl P. Butt

    2014-05-01

    The mechanical properties of AISI 304 stainless steel irradiated for over a decade in the Experimental Breeder Reactor (EBR-II) were measured using miniature mechanical testing methods. The shear punch method was used to evaluate the shear strengths of the neutron-irradiated steel and a correlation factor was empirically determined to predict its tensile strength. The strength of the stainless steel slightly decreased with increasing irradiation temperature, and significantly increased with increasing dose until it saturated above approximately 5 dpa. Ferromagnetic measurements were used to observe and deduce the effects of the stress-induced austenite to martensite transformation as a result of shear punch testing.

  7. Advanced neutron irradiation system using Texas A&M University Nuclear Science Center Reactor

    NASA Astrophysics Data System (ADS)

    Jang, Si Young

    A heavily filtered fast neutron irradiation system (FNIS) was developed for a variety of applications, including the study of long-term health effects of fast neutrons by evaluating the biological mechanisms of damage in cultured cells and living animals such as rats or mice. This irradiation system includes an exposure cave made with a lead-bismuth alloy, a cave positioning system, a gamma and neutron monitoring system, a sample transfer system, and interchangeable filters. This system was installed in the irradiation cell of the Texas A&M University Nuclear Science Center Reactor (NSCR). By increasing the thickness of the lead-bismuth alloy, the neutron spectra were shifted into lower energies by the scattering interactions of fast neutrons with the alloy. It is possible, therefore, by changing the alloy thickness, to produce distinctly different dose weighted neutron spectra inside the exposure cave of the FNIS. The calculated neutron spectra showed close agreement with the results of activation foil measurements, unfolded by SAND-II close to the cell window. However, there was a considerable less agreement for locations far away from the cell window. Even though the magnitude of values such as neutron flux and tissue kerma rates in air differed, the weighted average neutron energies showed close agreement between the MCNP and SAND-II since the normalized neutron spectra were in a good agreement each other. A paired ion chamber system was constructed, one with a tissue equivalent plastic (A-150) and propane gas for total dose monitoring, and another with graphite and argon for photon dose monitoring. Using the pair of detectors, the neutron to gamma ratio can be inferred. With the 20 cm-thick FNIS, the absorbed dose rates of neutrons measured with the paired ion chamber method and calculated with the SAND-II results were 13.7 +/- 0.02 Gy/min and 15.5 Gy/min, respectively. The absorbed dose rate of photons and the gamma contribution to total dose were 6.7 x 10

  8. Intergranular stress corrosion cracking susceptibility of neutron-irradiated, thermally sensitized type 304 stainless steel

    SciTech Connect

    Onchi, T.; Hide, K.; Mayuzumi, M.; Hoshiya, T.

    2000-05-01

    Austenitic stainless steels (SS) have been used as core component materials for light water reactors. As reactors age, however, the material tends to suffer from degradation primarily resulting from irradiation-assisted stress corrosion cracking (IASCC) as well as intergranular stress corrosion cracking (IGSCC). Neutron-irradiated, thermally sensitized Type 304 (UNS S30400) stainless steels (SS) were examined by slow strain rate (SSR) stress corrosion cracking (SCC) tests in 290 C water of 0.2 ppm dissolved oxygen concentration (DO) and by SSR tensile tests in 290 C inert gas environment. Neutron fluences ranged from 4 x 10{sup 22} n/m{sup 2} to 3 x 10{sup 25} n/m{sup 2} (energy [E] > 1 MeV). percent intergranular (%IG) cracking, which has been used as an intergranular (IG) cracking susceptibility indicator in the SSR SCC tests, changes anomalously with neutron fluence in spite of the strain-to-failure rate decreasing with an increase of neutron fluence. Apparently, %IG is a misleading indicator for the irradiated, thermally sensitized Type 304 SS and for the irradiated, nonsensitized SS when IG cracking susceptibility is compared at different neutron fluences, test temperatures, DO, and strain rates. These test parameters may affect deformation and fracture behaviors of the irradiated SS during the SSR SCC tests, resulting in changing %IG, which is given by the ratio of the total IG cracking area to the entire fracture surface area. It is suggested that strain-to-IG crack initiation for the irradiated, thermally sensitized SS and for the irradiated, nonsensitized SS is the alternative indicator in the SSR SCC tests. An engineering expedient to determine the IG crack initiation strain is given by a deviating point on superposed stress-strain curves in inert gas and in oxygenated water. The strain-to-IG crack initiation becomes smaller with an increase of neutron fluence and DO. The SSR tensile tests in inert gas are needed to obtain strain-to-IG crack initiation in

  9. Tritium release from neutron irradiated beryllium: Kinetics, long-time annealing and effect or crack formation

    SciTech Connect

    Scaffidi-Argentina, F.; Werle, H.

    1995-09-01

    Since beryllium is considered as one of the best neutron multiplier materials in the blanket of the next generation fusion reactors, several studies have been started to evaluate its behaviour under irradiation during both operating and accidental conditions. Based on safety considerations, tritium produced in beryllium during neutron irradiation represents one important issue, therefore it is necessary to investigate tritium transport processes by using a comprehensive mathematical model and comparing its predictions with well characterized experimental tests. Because of the difficulties in extrapolating the short-time tritium release tests to a longer time scale, also long-time annealing experiments with beryllium samples from the SIBELIUS irradiation. have been carried out at the Forschungszentrum Karlsruhe. Samples were annealed up to 12 months at temperatures up to 650{degrees}C. The inventory after annealing was determined by heating the samples up to 1050{degrees}C with a He+0.1 vo1% H{sub 2} purge gas. Furthermore, in order to investigate the likely effects of cracks formation eventually causing a faster tritium release from beryllium, the behaviour of samples irradiated at low temperature (40-50{degrees}C) but up to very high fast neutron fluences (0.8-3.9{center_dot}10{sup 22} cm{sup -2}, E{sub n}{ge}1 MeV) in the BR2 reactor has been investigated. Tritium was released by heating the beryllium samples up to 1050{degrees}C and purging them with He+0.1 vo1% H{sub 2}. Tritium release from high-irradiated beryllium samples showed a much faster kinetics than from the low-irradiated ones, probably because of crack formation caused by thermal stresses in the brittle material and/or by helium bubbles migration. The obtained experimental data have been compared with predictions of the code ANFIBE with the goal to better understand the physical mechanisms governing tritium behaviour in beryllium and to assess the prediction capabilities of the code.

  10. Laser excited novel near-infrared photoluminescence bands in fast neutron-irradiated MgO·nAl2O3

    NASA Astrophysics Data System (ADS)

    Rahman, Abu Zayed Mohammad Saliqur; Haseeb, A. S. M. A.; Xu, Qiu; Evslin, Jarah; Cinausero, Marco

    2016-08-01

    New near-infrared photoluminescence bands were observed in neutron-irradiated spinel single crystal upon excitation by a 532 nm laser. The surface morphology of the unirradiated and fast neutron-irradiated samples was investigated using atomic force microscopy and scanning probe microscopy. Fast neutron-irradiated samples show a strong emission peak at 1685 nm along with weak bands at 1065 and 2365 nm. The temperature dependence of the photoluminescence intensity was also measured. At lower temperatures, the dominant peak at 1685 nm shifts toward lower energy whereas the other peaks remain fixed. Activation energies of luminescence quenching were estimated to be 5.7 and 54.6 meV for the lower and higher temperature regions respectively.

  11. Microstructural developments in neutron-irradiated mild steel submerged-arc weld metal

    NASA Astrophysics Data System (ADS)

    Buswell, J. T.; Bischler, P. J. E.; Fenton, S. T.; Ward, A. E.; Phythian, W. J.

    1993-10-01

    The microstructures of Magnox submerged-arc welds have been characterised to investigate the effects of surveillance and accelerated irradiation at temperatures in the range 190-290°C. The radiation hardening and embrittlement is influenced by the precipitation of Cu from solid solution. Mn has been found in the Cu-rich precipitates, together with an indication of P. The precipitates have structure coherent with the ferrite matrix and maintain a constant mean diameter during extended irradiation. Evidence has been obtained indicating that dislocation loops contribute to a matrix damage component in these welds.

  12. Microstructural investigations of as-fabricated, long-term thermally aged and neutron irradiated RPV materials: An atom probe study

    SciTech Connect

    Pareige, P.J.; Miller, M.K.; Stoller, R.E.

    1995-09-01

    Atom probe field ton microscopy (APFIM) investigations of the microstructure of as-fabricated, long-term thermally aged ({approximately}100,000h. at 540{degrees}F (282{degrees}C)) and neutron-irradiated (6.6{times}10{sup 18} and 3.47{times}10{sup 19} n cm{sup {minus}2} (E>1 MeV) at {approximately}550{degrees}F (288{degrees}C)) surveillance materials from commercial reactor pressure vessel steels were performed This combination of materials and conditions permitted the investigation of potential thermal aging effects as well as the neutron-induced effects. The microstructural study focused on the quantification of the matrix chemistry and the detection and characterization of radiation-induced precipitates. The APFIM results indicate that there was no microstructural evolution after a long term-thermal exposure in weld (0.28 wt% Cu), plate (0.13 wt% Cu) or forging (0.02 wt% Cu) materials. Conversely, matrix depletion of copper and phosphorus solutes and the presence of Cu. P, Ni, Mn and Si rich clusters were observed in the neutron-irradiated weld material. These APFIM comparisons of materials in all three conditions are consistent with the measured change in mechanical properties (transition temperature shift).

  13. Neutron irradiation and frequency effects on the electrical conductivity of nanocrystalline silicon carbide (3C-SiC)

    NASA Astrophysics Data System (ADS)

    Huseynov, Elchin

    2016-09-01

    In this present work nanocrystalline silicon carbide (3C-SiC) has been irradiated with neutron flux (∼ 2 ×1013 ncm-2s-1) up to 20 hours at different periods. Electrical conductivity of nanocrystalline 3C-SiC particles (∼18 nm) is comparatively analyzed before and after neutron irradiation. The frequency dependencies of electrical conductivity of 3C-SiC nanoparticles is reviewed at 100 K-400 K temperature range before and after irradiation. The measurements were carried out at 0.1 Hz-2.5 MHz frequency ranges and at different temperatures. Radiation-induced conductivity (RIC) was observed in the nanocrystalline 3C-SiC particles after neutron irradiation and this conductivity study as a function of frequency are presented. The type of conductivity has been defined based on the interdependence between real and imaginary parts of electrical conductivity function. Based on the obtained results the mechanism behind the electrical conductivity of nanocrystalline 3C-SiC particles is explained in detail.

  14. RhG-CSF improves radiation-induced myelosuppression and survival in the canine exposed to fission neutron irradiation.

    PubMed

    Yu, Zu-Yin; Li, Ming; Han, A-Ru-Na; Xing, Shuang; Ou, Hong-Ling; Xiong, Guo-Lin; Xie, Ling; Zhao, Yan-Fang; Xiao, He; Shan, Ya-Jun; Zhao, Zhen-Hu; Liu, Xiao-Lan; Cong, Yu-Wen; Luo, Qing-Liang

    2011-01-01

    Fission-neutron radiation damage is hard to treat due to its critical injuries to hematopoietic and gastrointestinal systems, and so far few data are available on the therapeutic measures for neutron-radiation syndrome. This study was designed to test the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in dogs which had received 2.3 Gy mixed fission-neutron-γ irradiation with a high ratio of neutrons (~90%). Following irradiation, rhG-CSF treatment induced 100% survival versus 60% in controls. Only two of five rhG-CSF-treated dogs experienced leukopenia (white blood cells [WBC] count < 1.0 × 10(9)/L) and neutropenia (neutrophil [ANC] count < 0.5 × 10(9)/L), whereas all irradiated controls displayed a profound period of leukopenia and neutropenia. Furthermore, administration of rhG-CSF significantly delayed the onset of leukopenia and reduced the duration of leucopenia as compared with controls. In addition, individual dogs in the rhG-CSF-treated group exhibited evident differences in rhG-CSF responsiveness after neutron-irradiation. Finally, histopathological evaluation of the surviving dogs revealed that the incidence and severity of bone marrow, thymus and spleen damage decreased in rhG-CSF-treated dogs as compared with surviving controls. Thus, these results demonstrated that rhG-CSF administration enhanced recovery of myelopoiesis and survival after neutron-irradiation. PMID:21785235

  15. Atom Probe Tomography Characterization of the Solute Distributions in a Neutron-Irradiated and Annealed Pressure Vessel Steel Weld

    SciTech Connect

    Miller, M.K.

    2001-01-30

    A combined atom probe tomography and atom probe field ion microscopy study has been performed on a submerged arc weld irradiated to high fluence in the Heavy-Section Steel irradiation (HSSI) fifth irradiation series (Weld 73W). The composition of this weld is Fe - 0.27 at. % Cu, 1.58% Mn, 0.57% Ni, 0.34% MO, 0.27% Cr, 0.58% Si, 0.003% V, 0.45% C, 0.009% P, and 0.009% S. The material was examined after five conditions: after a typical stress relief treatment of 40 h at 607 C, after neutron irradiation to a fluence of 2 x 10{sup 23} n m{sup {minus}2} (E > 1 MeV), and after irradiation and isothermal anneals of 0.5, 1, and 168 h at 454 C. This report describes the matrix composition and the size, composition, and number density of the ultrafine copper-enriched precipitates that formed under neutron irradiation and the change in these parameters with post-irradiation annealing treatments.

  16. Enhancement of critical current density in fast neutron irradiated melt-textured YBa 2Cu 3O 7- x

    NASA Astrophysics Data System (ADS)

    Puźniak, R.; Wiśniewski, A.; Baran, M.; Szymczak, H.; Pingxiang, Zhang; Jingrong, Wang; Lian, Zhou; Pytel, K.; Pytel, B.

    The critical current density in melt-textured samples obtained by the powder melting process was determined from magnetization measurements. Linear dependence between the width of the hysteresis loop and sample size was observed for both unirradiated and irradiated samples. This indicates that the critical current is circulating through the whole sample and is not disconnected by weak links, even when a magnetic field is applied in the irradiated sample. After fast neutron irradiation with fluences from 5 × 10 16 to 6 × 10 17 n cm -2 ( E > 0.5 MeV), significant enhancement of the critical current density, jc, was observed. Critical current density, determined from magnetization measurements, for magnetic field perpendicular to the a-b plane, jcab, reaches - 10 5 A cm 42 at 77 K in 1 T. For H parallel to the a-b plane, jcc along the c-axis reaches 5 × 10 3 A cm -2. An increase in the anisotropy of the critical current was observed after fast neutron irradiation in the temperature range 60 - 80 K.

  17. A replica technique for extracting precipitates from neutron-irradiated or thermal-aged vanadium alloys for TEM analysis

    NASA Astrophysics Data System (ADS)

    Fukumoto, K.; Iwasaki, M.

    2014-06-01

    A carbon replica technique has been developed to extract precipitates from vanadium alloys. Using this technique, precipitation phases can be extracted from neutron-irradiated or thermal-aged V-4Cr-4Ti alloys. Precipitate identification using EDS X-ray analysis and electron diffraction was facilitated. Only NaCl type of Ti(OCN) precipitate was formed in the thermal-aged V-4Cr-4Ti alloys at 600 °C for 20 h and cation sub-lattice was only occupied by Ti atoms. However, the thin plate of precipitates with NaCl type of crystallographic structure could be seen in the V-4Cr-4Ti alloys irradiated at 593 °C in the JOYO fast reactor. The precipitate contained chromium and vanadium atoms on the cation sub-lattice as well as titanium atoms. It is considered that the phase of MX type (M = Ti, V, Cr and X = O, N, C) is a metastable phase under neutron irradiation.

  18. Effects of neutron irradiation on pinning force scaling in state-of-the-art Nb3Sn wires

    NASA Astrophysics Data System (ADS)

    Baumgartner, T.; Eisterer, M.; Weber, H. W.; Flükiger, R.; Scheuerlein, C.; Bottura, L.

    2014-01-01

    We present an extensive irradiation study involving five state-of-the-art Nb3Sn wires which were subjected to sequential neutron irradiation up to a fast neutron fluence of 1.6 × 1022 m-2 (E > 0.1 MeV). The volume pinning force of short wire samples was assessed in the temperature range from 4.2 to 15 K in applied fields of up to 7 T by means of SQUID magnetometry in the unirradiated state and after each irradiation step. Pinning force scaling computations revealed that the exponents in the pinning force function differ significantly from those expected for pure grain boundary pinning, and that fast neutron irradiation causes a substantial change in the functional dependence of the volume pinning force. A model is presented, which describes the pinning force function of irradiated wires using a two-component ansatz involving a point-pinning contribution stemming from radiation induced pinning centers. The dependence of this point-pinning contribution on fast neutron fluence appears to be a universal function for all examined wire types.

  19. The mechanism of solute-enriched clusters formation in neutron-irradiated pressure vessel steels: The case of Fe-Cu model alloys

    NASA Astrophysics Data System (ADS)

    Subbotin, A. V.; Panyukov, S. V.

    2016-08-01

    Mechanism of solute-enriched clusters formation in neutron-irradiated pressure vessel steels is proposed and developed in case of Fe-Cu model alloys. The suggested solute-drag mechanism is analogous to the well-known zone-refining process. We show that the obtained results are in good agreement with available experimental data on the parameters of clusters enriched with the alloying elements. Our model explains why the formation of solute-enriched clusters does not happen in austenitic stainless steels with fcc lattice structure. It also allows to quantify the method of evaluation of neutron irradiation dose for the process of RPV steels hardening.

  20. Electrochemical comparison and biological performance of a new CoCrNbMoZr alloy with commercial CoCrMo alloy.

    PubMed

    Andrei, M; Galateanu, B; Hudita, A; Costache, M; Osiceanu, P; Calderon Moreno, J M; Drob, S I; Demetrescu, I

    2016-02-01

    A new CoCrNbMoZr alloy, with Nb and Zr content is characterized from the point of view of surface features, corrosion resistance and biological performance in order to be proposed as dental restorative material. Its properties are discussed in comparison with commercial Heraenium CE alloy based on Co, Cr and Mo as well. The microstructure of both alloys was revealed by scanning electron microscopy (SEM). The composition and thickness of the alloy native passive films were identified by X-ray photoelectron spectroscopy (XPS). The surface characteristics were analyzed by atomic force microscopy (AFM) and contact angle techniques. The quantity of ions released from alloys in artificial saliva was evaluated with inductively coupled plasma-mass spectroscopy (ICP-MS) measurements. The electrochemical stability was studied in artificial Carter-Brugirard saliva, performing open circuit potentials, polarization resistances and corrosion currents and rates. The biological performance of the new alloy was tested in vitro in terms of human adipose stem cells (hASCs) morphology, viability and proliferation status. The new alloy is very resistant to the attack of the aggressive ions from the artificial saliva. The surface properties, the roughness and wettabiliy sustain the cell behavior. The comparison of the new alloy behavior with that of existing commercial CoCrMo alloy showed the superior properties of the new metallic biomaterial. PMID:26652383

  1. Mechanical and thermal properties of h-MX{sub 2} (M = Cr, Mo, W; X = O, S, Se, Te) monolayers: A comparative study

    SciTech Connect

    Çakır, Deniz Peeters, François M.; Sevik, Cem

    2014-05-19

    Using density functional theory, we obtain the mechanical and thermal properties of MX{sub 2} monolayers (where M = Cr, Mo, W and X = O, S, Se, Te). The Γ-centered phonon frequencies (i.e., A{sub 1}, A{sub 2}{sup ″}, E′, and E″), relative frequency values of A{sub 1}, and E′ modes, and mechanical properties (i.e., elastic constants, Young modulus, and Poisson's ratio) display a strong dependence on the type of metal and chalcogenide atoms. In each chalcogenide (metal) group, transition-metal dichalcogenides (TMDCs) with W (O) atom are found to be much stiffer. Consistent with their stability, the thermal expansion of lattice constants for TMDCs with O (Te) is much slower (faster). Furthermore, in a heterostructure of these materials, the difference of the thermal expansion of lattice constants between the individual components becomes quite tiny over the whole temperature range. The calculated mechanical and thermal properties show that TMDCs are promising materials for heterostructures.

  2. Theoretical predictions of properties and gas-phase chromatography behaviour of carbonyl complexes of group-6 elements Cr, Mo, W, and element 106, Sg

    NASA Astrophysics Data System (ADS)

    Pershina, V.; Anton, J.

    2013-05-01

    Fully relativistic, four-component density functional theory electronic structure calculations were performed for M(CO)6 of group-6 elements Cr, Mo, W, and element 106, Sg, with an aim to predict their adsorption behaviour in the gas-phase chromatography experiments. It was shown that seaborgium hexacarbonyl has a longer M-CO bond, smaller ionization potential, and larger polarizability than the other group-6 molecules. This is explained by the increasing relativistic expansion and destabilization of the (n - 1)d AOs with increasing Z in the group. Using results of the calculations, adsorption enthalpies of the group-6 hexacarbonyls on a quartz surface were predicted via a model of physisorption. According to the results, -ΔHads should decrease from Mo to W, while it should be almost equal - within the experimental error bars - for W and Sg. Thus, we expect that in the future gas-phase chromatography experiments it will be almost impossible - what concerns ΔHads - to distinguish between the W and Sg hexacarbonyls by their deposition on quartz.

  3. Theoretical predictions of properties and gas-phase chromatography behaviour of carbonyl complexes of group-6 elements Cr, Mo, W, and element 106, Sg.

    PubMed

    Pershina, V; Anton, J

    2013-05-01

    Fully relativistic, four-component density functional theory electronic structure calculations were performed for M(CO)6 of group-6 elements Cr, Mo, W, and element 106, Sg, with an aim to predict their adsorption behaviour in the gas-phase chromatography experiments. It was shown that seaborgium hexacarbonyl has a longer M-CO bond, smaller ionization potential, and larger polarizability than the other group-6 molecules. This is explained by the increasing relativistic expansion and destabilization of the (n - 1)d AOs with increasing Z in the group. Using results of the calculations, adsorption enthalpies of the group-6 hexacarbonyls on a quartz surface were predicted via a model of physisorption. According to the results, -ΔHads should decrease from Mo to W, while it should be almost equal--within the experimental error bars--for W and Sg. Thus, we expect that in the future gas-phase chromatography experiments it will be almost impossible--what concerns ΔHads--to distinguish between the W and Sg hexacarbonyls by their deposition on quartz.

  4. Hot pressing effect on the shear bond strength of dental porcelain to CoCrMoSi alloy substrates with different surface treatments.

    PubMed

    Henriques, B; Faria, S; Soares, D; Silva, F S

    2013-01-01

    The purpose of this study was to evaluate the effect of hot pressing on the shear bond strength of a CoCrMoSi alloy to a low-fusing feldspathic porcelain, for two types of surface treatments: polished and grit-blasted. Moreover, the shear strength of hot pressed porcelain was also compared with that of conventional vacuum sintered porcelain. Bond strength of metal-porcelain composites were assessed by the means of a shear test performed in a universal test machine until fracture. Fracture surfaces and interfaces were investigated by optical microscope, stereomicroscope and SEM/EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The 2-way ANOVA followed by Tukey HSD multiple comparison test was used to compare shear bond strength results and the t-test was used to compare the porcelain shear strength (p<0.05). Hot pressed specimens exhibited significantly (p<0.001) higher bond strength values than those obtained by conventional PFM technique. Significant differences (p<0.001) were found in the shear bond strength between grit-blasted and polished specimens. Significant differences (p<0.05) were also found between the shear strength of vacuum sintered and hot pressed porcelain. This study revealed that metal-ceramic bond strength is maximized for hot pressed porcelain onto rough metal substrates, with lower variability in results. Hot pressing technique was also shown to enhance the cohesion of porcelain.

  5. Effect of synovial fluid, phosphate-buffered saline solution, and water on the dissolution and corrosion properties of CoCrMo alloys as used in orthopedic implants.

    PubMed

    Lewis, A C; Kilburn, M R; Papageorgiou, I; Allen, G C; Case, C P

    2005-06-15

    The corrosion and dissolution of high- and low-carbon CoCrMo alloys, as used in orthopedic joint replacements, were studied by immersing samples in phosphate-buffered saline (PBS), water, and synovial fluid at 37 degrees C for up to 35 days. Bulk properties were analyzed with a fine ion beam microscope. Surface analyses by X-ray photoelectron spectroscopy and Auger electron spectroscopy showed surprisingly that synovial fluid produced a thin oxide/hydroxide layer. Release of ions into solution from the alloy also followed an unexpected pattern where synovial fluid, of all the samples, had the highest Cr concentration but the lowest Co concentration. The presence of carbide inclusions in the alloy did not affect the corrosion or the dissolution mechanisms, although the carbides were a significant feature on the metal surface. Only one mechanism was recognized as controlling the thickness of the oxide/hydroxide interface. The analysis of the dissolved metal showed two mechanisms at work: (1) a protein film caused ligand-induced dissolution, increasing the Cr concentration in synovial fluid, and was explained by the equilibrium constants; (2) corrosion at the interface increased the Co in PBS. The effect of prepassivating the samples (ASTM F-86-01) did not always have the desired effect of reducing dissolution. The release of Cr into PBS increased after prepassivation. The metal-synovial fluid interface did not contain calcium phosphate as a deposit, typically found where samples are exposed to calcium rich bodily fluids.

  6. Microstructures and mechanical properties of metastable Ti-30Zr-(Cr, Mo) alloys with changeable Young's modulus for spinal fixation applications.

    PubMed

    Zhao, Xiaoli; Niinomi, Mitsuo; Nakai, Masaaki; Miyamoto, Goro; Furuhara, Tadashi

    2011-08-01

    In order to develop a novel alloy with a changeable Young's modulus for spinal fixation applications, we investigated the microstructures, Young's moduli, and tensile properties of metastable Ti-30Zr-(Cr, Mo) alloys subjected to solution treatment (ST) and cold rolling (CR). All the alloys comprise a β phase and small athermal ω phase, and they exhibit low Young's moduli after ST. During CR, deformation-induced phase transformation occurs in all the alloys. The change in Young's modulus after CR is highly dependent on the type of deformation-induced phase. The increase in Young's modulus after CR is attributed to the deformation-induced ω phase on {3 3 2} mechanical twinning. Ti-30Zr-3Cr-3Mo (3Cr3Mo), which exhibits excellent tensile properties and a changeable Young's modulus, shows a smaller springback than Ti-29Nb-13Ta-4.6Zr, a β-type titanium alloy expected to be useful in spinal fixation applications. Thus, 3Cr3Mo is a potential candidate for spinal fixation applications. PMID:21569873

  7. Soluble and particulate Co-Cr-Mo alloy implant metals activate the inflammasome danger signaling pathway in human macrophages: a novel mechanism for implant debris reactivity.

    PubMed

    Caicedo, Marco S; Desai, Ronak; McAllister, Kyron; Reddy, Anand; Jacobs, Joshua J; Hallab, Nadim J

    2009-07-01

    Immune reactivity to soluble and particulate implant debris remains the primary cause of aseptic inflammation and implant loosening. However, the intracellular mechanisms that trigger immune cells to sense and respond to exogenous nonbiological agents such as metal particles or metal ions released from orthopedic implants remain unknown. Recent studies in immunology have outlined the importance of the intracellular inflammasome complex of proteins in sensing danger/stress signals triggered by nonbiological agents in the cytosol of macrophages. We hypothesized that metal implant debris can activate the inflammasome pathway in macrophages that causes caspase-1-induced cleavage of intracellular pro-IL-1beta into its mature form, resulting in IL-1beta secretion and induction of a broader proinflammatory response. We tested this hypothesis by examining whether soluble cobalt, chromium, molybdenum, and nickel ions and Co-Cr-Mo alloy particles induce inflammasome- mediated macrophage reactivity. Our results demonstrate that these agents stimulate IL-1beta secretion in human macrophages that is inflammasome mediated (i.e., NADPH-, caspase-1-, Nalp3-, and ASC-dependent). Thus, metal ion- and particle-induced activation of the inflammasome in human macrophages provides evidence of a novel pathway of implant debris-induced inflammation, where contact with implant debris is sensed and transduced by macrophages into a proinflammatory response.

  8. Hot pressing effect on the shear bond strength of dental porcelain to CoCrMoSi alloy substrates with different surface treatments.

    PubMed

    Henriques, B; Faria, S; Soares, D; Silva, F S

    2013-01-01

    The purpose of this study was to evaluate the effect of hot pressing on the shear bond strength of a CoCrMoSi alloy to a low-fusing feldspathic porcelain, for two types of surface treatments: polished and grit-blasted. Moreover, the shear strength of hot pressed porcelain was also compared with that of conventional vacuum sintered porcelain. Bond strength of metal-porcelain composites were assessed by the means of a shear test performed in a universal test machine until fracture. Fracture surfaces and interfaces were investigated by optical microscope, stereomicroscope and SEM/EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The 2-way ANOVA followed by Tukey HSD multiple comparison test was used to compare shear bond strength results and the t-test was used to compare the porcelain shear strength (p<0.05). Hot pressed specimens exhibited significantly (p<0.001) higher bond strength values than those obtained by conventional PFM technique. Significant differences (p<0.001) were found in the shear bond strength between grit-blasted and polished specimens. Significant differences (p<0.05) were also found between the shear strength of vacuum sintered and hot pressed porcelain. This study revealed that metal-ceramic bond strength is maximized for hot pressed porcelain onto rough metal substrates, with lower variability in results. Hot pressing technique was also shown to enhance the cohesion of porcelain. PMID:25428110

  9. Nanoscale Phase Separation In Epitaxial Cr-Mo and Cr-V Alloy Thin Films Studied Using Atom Probe Tomography. Comparison Of Experiments And Simulation

    SciTech Connect

    Devaraj, Arun; Kaspar, Tiffany C.; Ramanan, Sathvik; Walvekar, Sarita K.; Bowden, Mark E.; Shutthanandan, V.; Kurtz, Richard J.

    2014-11-21

    Tailored metal alloy thin film-oxide interfaces generated using molecular beam epitaxial (MBE) deposition of alloy thin films on a single crystalline oxide substrate can be used for detailed studies of irradiation damage response on the interface structure. However presence of nanoscale phase separation in the MBE grown alloy thin films can impact the metal-oxide interface structure. Due to nanoscale domain size of such phase separation it is very challenging to characterize by conventional techniques. Therefor laser assisted atom probe tomography (APT) was utilized to study the phase separation in epitaxial Cr0.61Mo0.39, Cr0.77Mo0.23, and Cr0.32V0.68 alloy thin films grown by MBE on MgO(001) single crystal substrates. Statistical analysis, namely frequency distribution analysis and Pearson coefficient analysis of experimental data was compared with similar analyses conducted on simulated APT datasets with known extent of phase separation. Thus the presence of phase separation in Cr-Mo films, even when phase separation was not clearly observed by x-ray diffraction, and the absence of phase separation in the Cr-V film were thus confirmed.

  10. Nanoscale phase separation in epitaxial Cr-Mo and Cr-V alloy thin films studied using atom probe tomography: Comparison of experiments and simulation

    SciTech Connect

    Devaraj, A.; Ramanan, S.; Walvekar, S.; Bowden, M. E.; Shutthanandan, V.; Kaspar, T. C.; Kurtz, R. J.

    2014-11-21

    Tailored metal alloy thin film-oxide interfaces generated using molecular beam epitaxy (MBE) deposition of alloy thin films on a single crystalline oxide substrate can be used for detailed studies of irradiation damage response on the interface structure. However, the presence of nanoscale phase separation in the MBE grown alloy thin films can impact the metal-oxide interface structure. Due to nanoscale domain size of such phase separation, it is very challenging to characterize by conventional techniques. Therefore, laser assisted atom probe tomography (APT) was utilized to study the phase separation in epitaxial Cr{sub 0.61}Mo{sub 0.39}, Cr{sub 0.77}Mo{sub 0.23}, and Cr{sub 0.32}V{sub 0.68} alloy thin films grown by MBE on MgO(001) single crystal substrates. Statistical analysis, namely frequency distribution analysis and Pearson coefficient analysis of experimental data was compared with similar analyses conducted on simulated APT datasets with known extent of phase separation. Thus, the presence of phase separation in Cr-Mo films, even when phase separation was not clearly observed by x-ray diffraction, and the absence of phase separation in the Cr-V film were confirmed.

  11. Electrochemical comparison and biological performance of a new CoCrNbMoZr alloy with commercial CoCrMo alloy.

    PubMed

    Andrei, M; Galateanu, B; Hudita, A; Costache, M; Osiceanu, P; Calderon Moreno, J M; Drob, S I; Demetrescu, I

    2016-02-01

    A new CoCrNbMoZr alloy, with Nb and Zr content is characterized from the point of view of surface features, corrosion resistance and biological performance in order to be proposed as dental restorative material. Its properties are discussed in comparison with commercial Heraenium CE alloy based on Co, Cr and Mo as well. The microstructure of both alloys was revealed by scanning electron microscopy (SEM). The composition and thickness of the alloy native passive films were identified by X-ray photoelectron spectroscopy (XPS). The surface characteristics were analyzed by atomic force microscopy (AFM) and contact angle techniques. The quantity of ions released from alloys in artificial saliva was evaluated with inductively coupled plasma-mass spectroscopy (ICP-MS) measurements. The electrochemical stability was studied in artificial Carter-Brugirard saliva, performing open circuit potentials, polarization resistances and corrosion currents and rates. The biological performance of the new alloy was tested in vitro in terms of human adipose stem cells (hASCs) morphology, viability and proliferation status. The new alloy is very resistant to the attack of the aggressive ions from the artificial saliva. The surface properties, the roughness and wettabiliy sustain the cell behavior. The comparison of the new alloy behavior with that of existing commercial CoCrMo alloy showed the superior properties of the new metallic biomaterial.

  12. Atom probe study of the carbon distribution in a hardened martensitic hot-work tool steel X38CrMoV5-1.

    PubMed

    Lerchbacher, Christoph; Zinner, Silvia; Leitner, Harald

    2012-07-01

    The microstructure of the hardened common hot-work tool steel X38CrMoV5-1 has been characterized by atom probe tomography with the focus on the carbon distribution. Samples quenched with technically relevant cooling parameters λ from 0.1 (30 K/s) to 12 (0.25 K/s) have been investigated. The parameter λ is an industrially commonly used exponential cooling parameter, representing the cooling time from 800 to 500 °C in seconds divided with hundred. In all samples pronounced carbon segregation to dislocations and cluster formation could be observed after quenching. Carbon enriched interlath films with peak carbon levels of 6-10 at.%, which have been identified to be retained austenite by TEM, show a thickness increase with increasing λ. Therefore, the fraction of total carbon staying in the austenite grows. This carbon is not available for the tempering induced precipitation of secondary carbides in the bulk. Through all samples no segregation of any substitutional elements takes place. Charpy impact testing and fracture surface analysis of the hardened samples reveal the cooling rate induced microstructural distinctions.

  13. Corrosion and Fretting Corrosion Studies of Medical Grade CoCrMo Alloy in a Clinically Relevant Simulated Body Fluid Environment

    NASA Astrophysics Data System (ADS)

    Ocran, Emmanuel K.; Guenther, Leah E.; Brandt, Jan-M.; Wyss, Urs; Ojo, Olanrewaju A.

    2015-06-01

    In modular hip implants, fretting corrosion at the head/neck and neck/stem interfaces has been identified as a major cause of early revision in hip implants, particularly those with heads larger than 32 mm. It has been found that the type of fluid used to simulate the fretting corrosion of biomedical materials is crucial for the reliability of laboratory tests. Therefore, to properly understand and effectively design against fretting corrosion damage in modular hips, there is the need to replicate the human body environment as closely as possible during in vitro testing. In this work, corrosion and fretting corrosion behavior of CoCrMo in 0.14 M NaCl, phosphate buffered saline, and in a clinically relevant novel simulated body fluid was studied using a variety of electrochemical characterization techniques and tribological experiments. Electrochemical, spectroscopy and tribo-electrochemical techniques employed include Potentiodynamic polarization, Potentiostatic polarization, Electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, augur electron spectroscopy, inductively coupled plasma mass spectroscopy, and pin-on-disk wear simulation. The presence of phosphate ions in PBS accounted for the higher corrosion rate when compared with 0.14 M NaCl and the clinically relevant novel simulated body fluid. The low corrosion rates and the nature of the protective passive film formed in the clinically relevant simulated body fluid make it suitable for future corrosion and fretting corrosion studies.

  14. Stress Corrosion Cracking of Ferritic Materials for Fossil Power Generation Applications

    SciTech Connect

    Pawel, Steven J; Siefert, John A.

    2014-01-01

    Creep strength enhanced ferritic (CSEF) steels Grades 23, 24, 91, and 92 have been widely implemented in the fossil fired industry for over two decades. The stress corrosion cracking (SCC) behavior of these materials with respect to mainstay Cr-Mo steels (such as Grades 11, 12 and 22) has not been properly assessed, particularly in consideration of recent reported issues of SCC in CSEF steels. This report details the results of Jones test exposures of a wide range of materials (Grades 11, 22, 23, 24, and 92), material conditions (as-received, improper heat treatments, normalized, weldments) and environments (salt fog; tube cleaning environments including decreasing, scale removal, and passivation; and high temperature water) to compare the susceptibility to cracking of these steels. In the as-received (normalized and tempered) condition, none of these materials are susceptible to SCC in the environments examined. However, in the hardened condition, certain combinations of environment and alloy reveal substantial SCC susceptibility.

  15. Contribution To Degradation Study, Behavior Of Unsaturated Polyester Resin Under Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Abellache, D.; Lounis, A.; Taïbi, K.

    2010-01-01

    Applications of unsaturated polyester thermosetting resins are numerous in construction sector, in transport, electric spare parts manufactures, consumer goods, and anticorrosive materials. This survey reports the effect of thermosetting polymer degradation (unsaturated polyester): degradation by neutrons irradiation. In order to evaluate the deterioration of our material, some comparative characterizations have been done between standard samples and damaged ones. Scanning electron microscopy (SEM), ultrasonic scanning, hardness test (Shore D) are the techniques which have been used. The exposure to a neutrons flux is carried out in the column of the nuclear research reactor of Draria (Algiers-Algeria). The energetic profile of the incidental fluxes is constituted of fast neutrons (ΦR = 3.1012n.cm-2.s-1, E = 2 Mev) of thermal neutrons (ΦTH = 1013n.cm-2.s-1; E = 0.025 ev) and epithermal neutrons (Φepi = 7.1011 n.cm-2.s-1; E>4,9 ev). The received dose flow is 0,4 Kgy. We notice only a few scientific investigations can be found in this field. In comparison with the standard sample (no exposed) it is shown that the damage degree is an increasing process with the exposure. Concerning the description of irradiation effects on polymers, we can advance that several reactions are in competition : reticulation, chain break, and oxidation by radical mechanism. In our case the incidental particle of high energy fast neutrons whose energy is greater or equal to 2 Mev, is braked by the target with a nuclear shock during which the incidental particle transmits a part of its energy to an atom. If the energy transfer is sufficient, the nuclear shock permits to drive out an atom of its site the latter will return positioning interstitially, the energy that we used oversteps probably the energy threshold (displacement energy). This fast neutrons collision with target cores proceeds to an indirect ionization by the preliminary creation of excited secondary species that will

  16. Contribution To Degradation Study, Behavior Of Unsaturated Polyester Resin Under Neutron Irradiation

    SciTech Connect

    Abellache, D.; Lounis, A.; Taiebi, K.

    2010-01-05

    Applications of unsaturated polyester thermosetting resins are numerous in construction sector, in transport, electric spare parts manufactures, consumer goods, and anticorrosive materials. This survey reports the effect of thermosetting polymer degradation (unsaturated polyester): degradation by neutrons irradiation. In order to evaluate the deterioration of our material, some comparative characterizations have been done between standard samples and damaged ones. Scanning electron microscopy (SEM), ultrasonic scanning, hardness test (Shore D) are the techniques which have been used. The exposure to a neutrons flux is carried out in the column of the nuclear research reactor of Draria (Algiers-Algeria). The energetic profile of the incidental fluxes is constituted of fast neutrons (PHI{sub R} = 3.10{sup 12} n.cm{sup -2}.s{sup -1}, E = 2 Mev) of thermal neutrons (PHI{sub TH} = 10{sup 13} n.cm{sup -2}.s{sup -1}; E = 0.025 ev) and epithermal neutrons (PHI{sub epi} = 7.10{sup 11} n.cm{sup -2}.s{sup -1}; E>4,9 ev). The received dose flow is 0,4 Kgy. We notice only a few scientific investigations can be found in this field. In comparison with the standard sample (no exposed) it is shown that the damage degree is an increasing process with the exposure. Concerning the description of irradiation effects on polymers, we can advance that several reactions are in competition: reticulation, chain break, and oxidation by radical mechanism. In our case the incidental particle of high energy fast neutrons whose energy is greater or equal to 2 Mev, is braked by the target with a nuclear shock during which the incidental particle transmits a part of its energy to an atom. If the energy transfer is sufficient, the nuclear shock permits to drive out an atom of its site the latter will return positioning interstitially, the energy that we used oversteps probably the energy threshold (displacement energy). This fast neutrons collision with target cores proceeds to an indirect

  17. Putting chromium on the map for N2 reduction: production of hydrazine and ammonia. A study of cis-M(N2)2 (M = Cr, Mo, W) bis(diphosphine) complexes.

    PubMed

    Egbert, Jonathan D; O'Hagan, Molly; Wiedner, Eric S; Bullock, R Morris; Piro, Nicholas A; Kassel, W Scott; Mock, Michael T

    2016-07-19

    The first complete structurally and spectroscopically characterized series of isostructural Group 6 N2 complexes is reported. Protonolysis experiments on cis-[M(N2)2(P(Et)N(R)P(Et))2] (M = Cr, Mo, W; R = 2,6-difluorobenzyl) reveal that only Cr affords N2H5(+) and NH4(+) from the reduction of the N2 ligands. PMID:27331373

  18. Characterization of the neutron irradiation system for use in the Low-Dose-Rate Irradiation Facility at Sandia National Laboratories.

    SciTech Connect

    Franco, Manuel,

    2014-08-01

    The objective of this work was to characterize the neutron irradiation system consisting of americium-241 beryllium (241AmBe) neutron sources placed in a polyethylene shielding for use at Sandia National Laboratories (SNL) Low Dose Rate Irradiation Facility (LDRIF). With a total activity of 0.3 TBq (9 Ci), the source consisted of three recycled 241AmBe sources of different activities that had been combined into a single source. The source in its polyethylene shielding will be used in neutron irradiation testing of components. The characterization of the source-shielding system was necessary to evaluate the radiation environment for future experiments. Characterization of the source was also necessary because the documentation for the three component sources and their relative alignment within the Special Form Capsule (SFC) was inadequate. The system consisting of the source and shielding was modeled using Monte Carlo N-Particle transport code (MCNP). The model was validated by benchmarking it against measurements using multiple techniques. To characterize the radiation fields over the full spatial geometry of the irradiation system, it was necessary to use a number of instruments of varying sensitivities. First, the computed photon radiography assisted in determining orientation of the component sources. With the capsule properly oriented inside the shielding, the neutron spectra were measured using a variety of techniques. A N-probe Microspec and a neutron Bubble Dosimeter Spectrometer (BDS) set were used to characterize the neutron spectra/field in several locations. In the third technique, neutron foil activation was used to ascertain the neutron spectra. A high purity germanium (HPGe) detector was used to characterize the photon spectrum. The experimentally measured spectra and the MCNP results compared well. Once the MCNP model was validated to an adequate level of confidence, parametric analyses was performed on the model to optimize for potential

  19. Effect of aging temperature on the microstructures and mechanical properties of ZG12Cr9Mo1Co1NiVNbNB ferritic heat-resistant steel

    NASA Astrophysics Data System (ADS)

    Yang, Xue; Sun, Lan; Xiong, Ji; Zhou, Ping; Fan, Hong-yuan; Liu, Jian-yong

    2016-02-01

    The effect of aging on the mechanical properties and microstructures of a new ZG12Cr9Mo1Co1NiVNbNB ferritic heat resistant steel was investigated in this work to satisfy the high steam parameters of the ultra-supercritical power plant. The results show that the main precipitates during aging are Fe(Cr, Mo)23C6, V(Nb)C, and (Fe2Mo) Laves in the steel. The amounts of the precipitated phases increase during aging, and correspondingly, the morphologies of phases are similar to be round. Fe(Cr, Mo)23C6 appears along boundaries and grows with increasing temperature. In addition, it is revealed that the martensitic laths are coarsened and eventually happen to be polygonization. The hardness and strength decrease gradually, whereas the plasticity of the steel increases. What's more, the hardness of this steel after creep is similar to that of other 9%-12%Cr ferritic steels. Thus, ZG12Cr9Mo1Co1NiVNbNB can be used in the project.

  20. X-ray diffraction study of BaTiO{sub 3} single crystals before and after fast-neutron irradiation

    SciTech Connect

    Stash, A. I. Ivanov, S. A.; Stefanovich, S. Yu.; Mosunov, A. V.; Boyko, V. M.; Ermakov, V. S.; Korulin, A. V.; Kalyukanov, A. I.; Isakova, N. N.

    2015-09-15

    The neutron irradiation of ferroelectrics is efficiently used to form structural states that cannot be obtained by conventional technologies. To date, the effect of neutron irradiation on the structure and properties of BaTiO{sub 3} has been studied for only ceramic materials. We have considered the influence of fast-neutron irradiation (F = 1 × 10{sup 17} cm{sup −2}) on the structure and properties of BaTiO{sub 3} single crystals for the first time. The structural changes occurring in irradiated BaTiO{sub 3} and their correlation with the behavior of dielectric and nonlinear optical characteristics are analyzed with the aid of a specially developed method for taking into account the experimental correction to diffuse scattering. Neutron irradiation to the aforementioned dose retains the polar structure of the material and only slightly changes atomic displacements. The radiationinduced structural changes occur according to the high-temperature type to form a structure similar to the cubic modification of unirradiated BaTiO{sub 3} crystal.

  1. Inverse magnetocaloric effect in Ce(Fe{sub 0.96}Ru{sub 0.04}){sub 2}: Effect of fast neutron irradiation

    SciTech Connect

    Dube, V.; Mishra, P. K.; Prajapat, C. L.; Singh, M. R.; Ravikumar, G.; Rajarajan, A. K.; Sastry, P. U.; Thakare, S. V.

    2013-02-05

    We have shown the effect of fast neutron irradiation on the magnetic phase transition and magnetocaloric effect (MCE) in a doped Ce(Fe{sub 0.96}Ru{sub 0.04}){sub 2}, intermettalic. We show that this leads to suppression of MCE and a to a disordered ferromagnetic phase.

  2. Effect of neutron irradiation on the properties of the repair welds of the 15Kh2MFA steel

    SciTech Connect

    Morozov, A.M.; Khachaturyants, L.V.

    1986-07-01

    The authors studied the effect of neutron irradiation on the tendency of the metal belonging to the heat affected zone of the weld toward brittle fracture (an increase in the critical temperature of brittleness). For comparison, the authors studied the radiation embrittlement of the original base metal (steel 15Kh2MFA) subjected to the conventional heat treatment of the reactor frames consisting of hardening and high-temperature tempering. Along with these materials, the radiational embrittlement of the base metal in the rehardened condition without tempering was studied. It was concluded that the presence of the regions repaired according to this technology and located in the frame at the level of the reactor core does not pose the problem of decreased resistance to brittle fracture.

  3. Nuclear microprobe analysis of 7Li profile induced in HfB 2 by a neutron irradiation

    NASA Astrophysics Data System (ADS)

    Simeone, D.; Deschanels, X.; Gosset, D.; Bonal, J. P.; Berthoumieux, E.

    2001-09-01

    HfB 2, a solid poor in boron, was irradiated by thermal neutrons in an experimental reactor. Using a nuclear microprobe, we have tracked lithium atoms produced by the 10B( n, α) 7Li reaction and compared the calculated and measured 7Li profiles in HfB 2 irradiated samples. This comparison shows that Li atoms do not diffuse during irradiation (323 K). The comparison of non-annealed and annealed irradiated HfB 2 plates clearly shows that lithium atoms do not migrate out of samples even at high temperatures (1273 K). These results associated to previous transmission electron microscopy (TEM) observations seem to show that lithium atoms are trapped by dislocation loops created by displacement cascades during neutron irradiation.

  4. EPR study of gamma and neutron irradiation effects on KU1, KS-4V and Infrasil 301 silica glasses

    NASA Astrophysics Data System (ADS)

    Lagomacini, Juan C.; Bravo, David; León, Mónica; Martín, Piedad; Ibarra, Ángel; Martín, Agustín; López, Fernando J.

    2011-10-01

    Electron paramagnetic resonance (EPR) studies have been carried out on KU1 and KS-4V high purity quartz glasses and commercial silica Infrasil 301, irradiated with gamma rays up to a dose of 11.6 MGy and neutron fluences of 10 21 and 10 22 n/m 2. Gamma irradiations produce a much higher concentration of defect centres (mainly E', POR and NBOHC) for KU1 and I301 than for KS-4V silica. In contrast, neutron irradiation at the highest fluence produces similar concentrations in all silica types. These results agree to a good extent with those obtained in previous optical absorption measurements. Moreover, oxygen-related centres (POR and NBOHC) have been well characterized by means of electron paramagnetic resonance.

  5. Ionizing/displacement synergistic effects induced by gamma and neutron irradiation in gate-controlled lateral PNP bipolar transistors

    NASA Astrophysics Data System (ADS)

    Wang, Chenhui; Chen, Wei; Yao, Zhibin; Jin, Xiaoming; Liu, Yan; Yang, Shanchao; Wang, Zhikuan

    2016-09-01

    A kind of gate-controlled lateral PNP bipolar transistor has been specially designed to do experimental validations and studies on the ionizing/displacement synergistic effects in the lateral PNP bipolar transistor. The individual and mixed irradiation experiments of gamma rays and neutrons are accomplished on the transistors. The common emitter current gain, gate sweep characteristics and sub-threshold sweep characteristics are measured after each exposure. The results indicate that under the sequential irradiation of gamma rays and neutrons, the response of the gate-controlled lateral PNP bipolar transistor does exhibit ionizing/displacement synergistic effects and base current degradation is more severe than the simple artificial sum of those under the individual gamma and neutron irradiation. Enough attention should be paid to this phenomenon in radiation damage evaluation.

  6. Degradation of Nylon 6,6 Fire-Suppression Casing from Plutonium Glove Boxes Under Alpha and Neutron Irradiation

    SciTech Connect

    Millsap, Donald W.; Cournoyer, Michael E.; Landsberger, Sheldon; Tesmer, Joseph R.; Wang, Matthew Y.

    2015-04-23

    Nylon 6,6 tensile specimens, conforming to the casing for self-contained fire extinguisher systems, have been irradiated using both an accelerator He++ ion beam and a 5-Ci PuBe neutron source to model the radiation damage these systems would likely incur over a lifetime of operation within glove boxes. Following irradiation, these samples were mechanically tested using standard practices as described in ASTM D638. The results of the He++ study indicate that the tensile strength of the nylon specimens undergoes some slight (<10%) degradation while other properties of the samples, such as elongation and tangent modulus, appear to fluctuate with increasing dose levels. The He++-irradiated specimens also have a noticeable level of discoloration corresponding to increasing levels of dose. The neutron-irradiated samples show a higher degree of mechanical degradation than the He++-irradiated samples.

  7. Degradation of Nylon 6,6 Fire-Suppression Casing from Plutonium Glove Boxes Under Alpha and Neutron Irradiation

    DOE PAGESBeta

    Millsap, Donald W.; Cournoyer, Michael E.; Landsberger, Sheldon; Tesmer, Joseph R.; Wang, Matthew Y.

    2015-04-23

    Nylon 6,6 tensile specimens, conforming to the casing for self-contained fire extinguisher systems, have been irradiated using both an accelerator He++ ion beam and a 5-Ci PuBe neutron source to model the radiation damage these systems would likely incur over a lifetime of operation within glove boxes. Following irradiation, these samples were mechanically tested using standard practices as described in ASTM D638. The results of the He++ study indicate that the tensile strength of the nylon specimens undergoes some slight (<10%) degradation while other properties of the samples, such as elongation and tangent modulus, appear to fluctuate with increasing dosemore » levels. The He++-irradiated specimens also have a noticeable level of discoloration corresponding to increasing levels of dose. The neutron-irradiated samples show a higher degree of mechanical degradation than the He++-irradiated samples.« less

  8. High Dose Neutron Irradiation of Hi-Nicalon Type S Silicon Carbide Composites, Part 2. Mechanical and Physical Properties

    SciTech Connect

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao Phillip; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wallace D; Snead, Lance Lewis

    2015-01-07

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573–1073 K. Likewise, the material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating the irradiation temperature, but only to a limited extent. Moreover, the observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.

  9. High-dose neutron irradiation of Hi-Nicalon Type S silicon carbide composites. Part 2: Mechanical and physical properties

    NASA Astrophysics Data System (ADS)

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wally; Snead, Lance L.

    2015-07-01

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573-1073 K. The material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating the irradiation temperature, but only to a limited extent. The observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.

  10. Microstructural evolution of NF709 (20Cr-25Ni-1.5MoNbTiN) under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Kim, B. K.; Tan, L.; Xu, C.; Yang, Y.; Zhang, X.; Li, M.

    2016-03-01

    Because of its superior creep and corrosion resistance as compared with general austenitic stainless steels, NF709 has emerged as a candidate structural material for advanced nuclear reactors. To obtain fundamental information about the radiation resistance of this material, this study examined the microstructural evolution of NF709 subjected to neutron irradiation to 3 displacements per atom at 500 °C. Transmission electron microscopy, scanning electron microscopy, and high-energy x-ray diffraction were employed to characterize radiation-induced segregation, Frank loops, voids, as well as the formation and reduction of precipitates. Radiation hardening of ∼76% was estimated by nanoindentation, approximately consistent with the calculation according to the dispersed barrier-hardening model, suggesting Frank loops as the primary hardening source.

  11. Microstructural evolution of NF709 (20Cr–25Ni–1.5MoNbTiN) under neutron irradiation

    DOE PAGESBeta

    Kim, Byoungkoo; Tan, Lizhen; Xu, C.; Yang, Yong; Zhang, Xuan; Li, Meimei

    2015-12-30

    In this study, because of its superior creep and corrosion resistance as compared with general austenitic stainless steels, NF709 has emerged as a candidate structural material for advanced nuclear reactors. To obtain fundamental information about the radiation resistance of this material, this study examined the microstructural evolution of NF709 subjected to neutron irradiation to 3 displacements per atom at 500 °C. Transmission electron microscopy, scanning electron microscopy, and high-energy x-ray diffraction were employed to characterize radiation-induced segregation, Frank loops, voids, as well as the formation and reduction of precipitates. Radiation hardening of ~76% was estimated by nanoindentation, approximately consistent withmore » the calculation according to the dispersed barrier-hardening model, suggesting Frank loops as the primary hardening source.« less

  12. Microstructural evolution of NF709 (20Cr–25Ni–1.5MoNbTiN) under neutron irradiation

    SciTech Connect

    Kim, Byoungkoo; Tan, Lizhen; Xu, C.; Yang, Yong; Zhang, Xuan; Li, Meimei

    2015-12-30

    In this study, because of its superior creep and corrosion resistance as compared with general austenitic stainless steels, NF709 has emerged as a candidate structural material for advanced nuclear reactors. To obtain fundamental information about the radiation resistance of this material, this study examined the microstructural evolution of NF709 subjected to neutron irradiation to 3 displacements per atom at 500 °C. Transmission electron microscopy, scanning electron microscopy, and high-energy x-ray diffraction were employed to characterize radiation-induced segregation, Frank loops, voids, as well as the formation and reduction of precipitates. Radiation hardening of ~76% was estimated by nanoindentation, approximately consistent with the calculation according to the dispersed barrier-hardening model, suggesting Frank loops as the primary hardening source.

  13. Effects of neutron irradiation on dimensional stability and on mechanical properties of SiC/SiC composites

    SciTech Connect

    Youngblood, G.E.; Henager, C.H. Jr.; Senor, J.

    1995-04-01

    The objective of this work is to assess the development and the performance of continuous fiber SiC{sub f}/SiC composites as a structural material for advanced fusion reactor application. The dimensional stability and some mechanical properties of two similar 2D 0-90{degree} weave SiC{sub f}/SiC composites made with Nacalon{trademark} ceramic-grade fiber were characterized and compared after neutron irradiation to those properties for {beta}-SiC. The major difference between these two composites was that one had a thin (150 nm) and the other a thick (1000 nm) graphite interface layer. The irradiation conditions consisted of relatively high doses (4.3 to 26 dpa-SiC) at high temperature (430-1200{degree}C).

  14. Fission reactor based epithermal neutron irradiation facilities for routine clinical application in BNCT--Hatanaka memorial lecture.

    PubMed

    Harling, Otto K

    2009-07-01

    Based on experience gained in the recent clinical studies at MIT/Harvard, the desirable characteristics of epithermal neutron irradiation facilities for eventual routine clinical BNCT are suggested. A discussion of two approaches to using fission reactors for epithermal neutron BNCT is provided. This is followed by specific suggestions for the performance and features needed for high throughput clinical BNCT. An example of a current state-of-the-art, reactor based facility, suited for routine clinical use is discussed. Some comments are provided on the current status of reactor versus accelerator based epithermal neutron sources for BNCT. This paper concludes with a summary and a few personal observations on BNCT by the author.

  15. Cold-rolling behavior of biomedical Ni-free Co-Cr-Mo alloys: Role of strain-induced ε martensite and its intersecting phenomena.

    PubMed

    Mori, Manami; Yamanaka, Kenta; Chiba, Akihiko

    2015-03-01

    Ni-free Co-Cr-Mo alloys are some of the most difficult-to-work metallic materials used commonly in biomedical applications. Since the difficulty in plastically deforming them limits their use, an in-depth understanding of their plastic deformability is of crucial importance for both academic and practical purposes. In this study, the microstructural evolution of a Co-29Cr-6Mo-0.2N (mass%) alloy during cold rolling was investigated. Further, its work-hardening behavior is discussed while focusing on the strain-induced face-centered cubic (fcc) γ→hexagonal close-packed (hcp) ε martensitic transformation (SIMT). The planar dislocation slip and subsequent SIMT occurred even in the initial stage of the deformation process owing to the low stability of the γ-phase and contributed to the work hardening behavior. However, the amount of the SIMTed ε-phase did not explain the overall variation in work hardening during cold rolling. It was found that the intersecting of the SIMTed ε-plates enhanced local strain evolution and then produced fine domain-like deformation microstructures at the intersections. Consequently, the degree of work hardening was reduced during subsequent plastic deformation, resulting in the alloy exhibiting a two-stage work hardening behavior. The results obtained in this study suggest that the interaction between ε-martensites, and ultimately its relaxation mechanism, is of significant importance; therefore, this aspect should be addressed in detail; the atomic structures of the γ-matrix/ε-martensite interfaces, the phenomenon of slip transfer at the interfaces, and the slipping behavior of the ε-phase itself are needed to be elucidated for further increasing the cold deformability of such alloys.

  16. Transition Metal Complexes of Cr, Mo, W and Mn Containing {eta}{sup 1}(S)-2,5-Dimethylthiophene, Benzothiophene and Dibenzothiophene Ligands

    SciTech Connect

    Reynolds, M.

    2000-09-21

    The UV photolysis of hexanes solutions containing the complexes M(CO){sub 6} (M=Cr, Mo, W) or CpMn(CO){sub 3} (Cp={eta}{sup 5}-C{sub 5}H{sub 5}) and excess thiophene (T{sup *}) (T{sup *}=2,5-dimethylthiophene (2,5-Me{sub 2}T), benzothiophene (BT), and dibenzothiophene (DBT)) produces the {eta}{sup 1}(S)-T{sup *} complexes (CO){sub 5}M({eta}{sup 1}(S)-T{sup *}) 1-8 or Cp(CO){sub 2}Mn({eta}{sup 1}(S)-T{sup *})9-11, respectively. However, when T{sup *}=DBT, and M=Mo, a mixture of two products result which includes the {eta}{sup 1}(S)-DBT complex (CO){sub 5}Mo({eta}{sup 1}(S)-DBT) 4a and the unexpected {pi}-complex (CO){sub 3}Mo({eta}{sup 6}-DBT) 4b as detected by {sup 1}H NMR. The liability of the {eta}{sup 1}(S)-T{sup *} ligands is illustrated by the rapid displacement of DBT in the complex (CO){sub 5}W({eta}{sup 1}(S)-DBT) (1) by THF, and also in the complexes (CO){sub 5}Cr({eta}{sup 1}(S)-DBT) (5) and CpMn(CO){sub 2}({eta}{sup 1}(S)-DBT) (9) by CO (1 atm) at room temperature. Complexes 1-11 have been characterized spectroscopically ({sup 1}H NMR, IR) and when possible isolated as analytically pure solids (elemental analysis, EIMS). Single crystal, X-ray structural determinations are reported for (CO){sub 5}W({eta}{sup 1}(S)-DBT) and Cp(CO){sub 2}Mn({eta}{sup 1}(S)-DBT).

  17. Metal-Centered 17-Electron Radicals CpM(CO)3• (M = Cr, Mo, W): A Combined Negative Ion Photoelectron Spectroscopic and Theoretical Study

    SciTech Connect

    van der Eide, Edwin F.; Hou, Gao-Lei; Deng, Shihu; Wen, Hui; Yang, Ping; Bullock, R. Morris; Wang, Xue B.

    2013-04-08

    Despite the importance of group VI metal-centered 17-electron radicals CpM(CO)3 (Cp = 5-C5H5, M = Cr, Mo, W) in establishing many of the fundamental reactions now known for metal-centered radicals, spectroscopic characterization of their electronic properties and structures has been very challenging due to their high reactivity. Here we report a gas-phase study of these species by means of photodetachment photoelectron spectroscopy (PES) of their corresponding 18-electron anions and theoretical electronic structure calculations. Three well-separated spectral features are observed by PES for each anionic species. Electron affinities (EAs) of CpM(CO)3 were experimentally measured from the threshold of each spectrum to be 2.38 ± 0.02 (M = Cr), 2.63 ± 0.02 (Mo), and 2.63 ± 0.01 eV for (W), well correlated with the reported redox potentials measured in solution. Theoretical calculations for all anionic and neutral (radical) species gave calculated EAs and band gaps that are in good agreement with the experimental data. Molecular orbital (MO) analyses for each anion indicate that the top three occupied MOs are mainly metal-based and contribute to the first spectral feature, whereas the next two MOs are largely from C5H5 moiety and contribute to the second spectral feature. The calculations further exhibit appreciable anion-to-neutral structural changes for all three species but with the change for the W species being the smallest, consistent with the W spectra being better resolved than the other two.

  18. Trace element (Al, As, B, Ba, Cr, Mo, Ni, Se, Sr, Tl, U and V) distribution and seasonality in compartments of the seagrass Cymodocea nodosa.

    PubMed

    Malea, Paraskevi; Kevrekidis, Theodoros

    2013-10-01

    Novel information on the biological fate of trace elements in seagrass ecosystems is provided. Al, As, B, Ba, Cr, Mo, Ni, Se, Sr, Tl, U and V concentrations in five compartments (blades, sheaths, vertical rhizomes, main axis plus additional branches, roots) of the seagrass Cymodocea nodosa, as well as in seawater and sediments from the Thessaloniki Gulf, Greece were determined monthly. Uni- and multivariate data analyses were applied. Leaf compartments and roots displayed higher Al, Mo, Ni and Se annual mean concentrations than rhizomes, B was highly accumulated in blades and Cr in sheaths; As, Ba, Sr and Tl contents did not significantly vary among plant compartments. A review summarizing reported element concentrations in seagrasses has revealed that C. nodosa sheaths display a high Cr accumulation capacity. Most element concentrations in blades increased in early mid-summer and early autumn with blade size and age, while those in sheaths peaked in late spring-early summer and autumn when sheath size was the lowest; elevated element concentrations in seawater in late spring and early-mid autumn, possibly as a result of elevated rainfall and associated run-off from the land, may have also contributed to the observed variability. Element concentrations in rhizomes and roots generally displayed a temporary increase in late autumn, which was concurrent with high rainfall, low wind speed associated with reduced hydrodynamism, and elevated sediment element levels. The bioaccumulation factor based on element concentrations in seagrass compartments and sediments was lower than 1 except for B, Ba, Mo, Se and Sr in all compartments, Cr in sheaths and U in roots. Blade V concentration positively correlated with sediment V concentration, suggesting that C. nodosa could be regarded as a bioindicator for V. Our findings can contribute to the design of biomonitoring programs and the development of predictive models for rational management of seagrass meadows. PMID:23838054

  19. Subtask 12F4: Effects of neutron irradiation on the impact properties and fracture behavior of vanadium-base alloys

    SciTech Connect

    Chung, H.M.; Loomis, B.A.; Smith, D.L.

    1995-03-01

    Up-to-date results on the effects of neutron irradiation on the impact properties and fracture behavior of V, V-Ti, V-Cr-Ti and V-Ti-Si alloys are presented in this paper, with an emphasis on the behavior of the U.S. reference alloys V-4Cr-4Ti containing 500-1000 wppm Si. Database on impact energy and cluctile-brittle transition temperature (DBTT) has been established from Charpy impact tests of one-third-size specimens irradiated at 420{degrees}C-600{degrees}C up to {approx}50 dpa in lithium environment in fast fission reactors. To supplement the Charpy impact tests fracture behavior was also characterized by quantitative SEM fractography on miniature tensile and disk specimens that were irradiated to similar conditions and fractured at -196{degrees}C to 200{degrees}C by multiple bending. For similar irradiation conditions irradiation-induced increase in DBTT was influenced most significantly by Cr content, indicating that irradiation-induced clustering of Cr atoms takes place in high-Cr (Cr {ge} 7 wt.%) alloys. When combined contents of Cr and Ti were {le}10 wt.%, effects of neutron irradiation on impact properties and fracture behavior were negligible. For example, from the Charpy-impact and multiple-bend tests there was no indication of irradiation-induced embrittlement for V-5Ti, V-3Ti-1Si and the U.S. reference alloy V-4Cr-4Ti after irradiation to {approx}34 dpa at 420{degrees}C to 600{degrees}C, and only ductile fracture was observed for temperatures as low as -196{degrees}C. 14 refs., 8 figs., 1 tab.

  20. Holmium-loaded PLLA nanoparticles for intratumoral radiotherapy via the TMT technique: preparation, characterization, and stability evaluation after neutron irradiation.

    PubMed

    Hamoudeh, Misara; Fessi, Hatem; Salim, Hani; Barbos, Dumitru

    2008-08-01

    This article describes the preparation of biocompatible radioactive holmium-loaded particles with appropriate nanoscale size for radionuclide intratumoral administration by the targeted multitherapy (TMT) technique. For this objective, holmium acetylacetonate has been encapsulated in poly-L-lactide (PLLA)-based nanoparticles (NP) by oil-in-water emulsion-solvent evaporation method. NP sizes ranged between 100 and 1,100 m being suitable for the TMT administration method. Elemental holmium loading was found to be around 18% wt/wt and the holmium acetylacetonate trihydrate (HoAcAc) encapsulation efficacy was about 90%. Different experiments demonstrated an amorphous state of HoAcAc after incorporation in NPs. The NPs were irradiated in a nuclear reactor with a neutron flux of 1.1 x 10(13) n/cm(2)/s for 1 h, which yielded a specific activity of about 27.4 GBq/g of NPs being sufficient for our desired application. Microscopic analysis of irradiated NPs showed some alteration after neutron irradiation as some NPs looked partially coagglomerated and a few pores appeared at their surface because of the locally released heat in the irradiation vials. Furthermore, differential scanning calorimetry (DSC) results indicated a clear decrease in PLLA melting point and melting enthalpy reflecting a decrease in polymer crystallinity. This was accompanied by a clear decrease in polymer molecular weights, which can be ascribed to a radiation-induced chain scission mechanism. However, interestingly, other experiments confirmed the chemical identity retention of both HoAcAc and PLLA in irradiated NPs despite this detected decrease in the polymer crystallinity and molecular weight. Although neutron irradiation has induced some NPs damage, these NPs kept out their overall chemical composition, and their size distribution remained suitable for the TMT administration technique. Coupled with the TMT technique, these NPs may represent a novel potential radiopharmaceutical agent for

  1. STEM-EDS analysis of fission products in neutron-irradiated TRISO fuel particles from AGR-1 experiment

    NASA Astrophysics Data System (ADS)

    Leng, B.; van Rooyen, I. J.; Wu, Y. Q.; Szlufarska, I.; Sridharan, K.

    2016-07-01

    Historic and recent post-irradiation-examination from the German AVR and Advanced Gas Reactor Fuel Development and Qualification Project have shown that 110 m Ag is released from intact tristructural isotropic (TRISO) fuel. Although TRISO fuel particle research has been performed over the last few decades, little is known about how metallic fission products are transported through the SiC layer, and it was not until March 2013 that Ag was first identified in the SiC layer of a neutron-irradiated TRISO fuel particle. The existence of Pd- and Ag-rich grain boundary precipitates, triple junction precipitates, and Pd nano-sized intragranular precipitates in neutron-irradiated TRISO particle coatings was investigated using Scanning Transmission Electron Microscopy and Energy Dispersive Spectroscopy analysis to obtain more information on the chemical composition of the fission product precipitates. A U-rich fission product honeycomb shape precipitate network was found near a micron-sized precipitate in a SiC grain about ∼5 μm from the SiC-inner pyrolytic carbon interlayer, indicating a possible intragranular transport path for uranium. A single Ag-Pd nano-sized precipitate was found inside a SiC grain, and this is the first research showing such finding in irradiated SiC. This finding may possibly suggest a possible Pd-assisted intragranular transport mechanism for Ag and may be related to void or dislocation networks inside SiC grains. Preliminary semi-quantitative analysis indicated the micron-sized precipitates to be Pd2Si2U with carbon existing inside these precipitates. However, the results of such analysis for nano-sized precipitates may be influenced by the SiC matrix. The results reported in this paper confirm the co-existence of Cd with Ag in triple points reported previously.

  2. Effects of thermal aging and neutron irradiation on the mechanical properties of three-wire stainless steel weld overlay cladding

    SciTech Connect

    Haggag, F.M.; Nanstad, R.K.

    1997-05-01

    Thermal aging of three-wire series-arc stainless steel weld overlay cladding at 288{degrees}C for 1605 h resulted in an appreciable decrease (16%) in the Charpy V-notch (CVN) upper-shelf energy (USE), but the effect on the 41-J transition temperature shift was very small (3{degrees}C). The combined effect of aging and neutron irradiation at 288{degrees}C to a fluence of 5 x 10{sup 19} neutrons/cm{sup 2} (> 1 MeV) was a 22% reduction in the USE and a 29{degrees}C shift in the 41-J transition temperature. The effect of thermal aging on tensile properties was very small. However, the combined effect of irradiation and aging was an increase in the yield strength (6 to 34% at test temperatures from 288 to {minus}125{degrees}C) but no apparent change in ultimate tensile strength or total elongation. Neutron irradiation reduced the initiation fracture toughness (J{sub Ic}) much more than did thermal aging alone. Irradiation slightly decreased the tearing modulus, but no reduction was caused by thermal aging alone. Other results from tensile, CVN, and fracture toughness specimens showed that the effects of thermal aging at 288 or 343{degrees}C for 20,000 h each were very small and similar to those at 288{degrees}C for 1605 h. The effects of long-term thermal exposure time (50,000 h and greater) at 288{degrees}C will be investigated as the specimens become available in 1996 and beyond.

  3. Overview of the US-Japan collaborative investigation on hydrogen isotope retention in neutron-irradiated and ion-damaged tungsten

    SciTech Connect

    Masashi Shimada; Y. Hatano; Y. Oya; T. Oda; M. Hara; G. Cao; M. Kobayashi; M. Sokolov; H. Watanabe; B. Tyburska; Y. Ueda; P. Calderoni

    2011-09-01

    Plasma-facing components (PFCs) will be exposed to 14 MeV neutrons from deuterium-tritium (D-T) fusion reactions, and tungsten, a candidate PFC for the divertor in ITER, is expected to receive a neutron dose of 0.7 displacement per atom (dpa) by the end of operation in ITER. The effect of neutron-irradiation damage has been mainly simulated using high-energy ion bombardment. While this prior database of results is quite valuable for understanding the behavior of hydrogen isotopes in PFCs, it does not encompass the full range of effects that must be considered in a practical fusion environment due to short penetration depth, damage gradient, high damage rate, and high PKA energy spectrum of the ion bombardment. In addition, neutrons change the elemental composition via transmutations, and create a high radiation environment inside PFCs, which influence the behavior of hydrogen isotope in PFCs, suggesting the utilization of fission reactors is necessary for neutron irradiation. Therefore, the effort to correlate among high-energy ions, fission neutrons, and fusion neutrons is crucial for accurately estimating tritium retention under a neutron-irradiation environment. Under the framework of the US-Japan TITAN program, tungsten samples (99.99 at. % purity from A.L.M.T. Co.) were irradiated by neutron in the High Flux Isotope Reactor (HFIR), ORNL, at 50 and 300C to 0.025, 0.3, and 1.2 dpa, and the investigation of deuterium retention in neutron-irradiation was performed in the INL Tritium Plasma Experiment (TPE), the unique high-flux linear plasma facility that can handle tritium, beryllium and activated materials. This paper reports the recent results from the comparison of ion-damaged tungsten via various ion species (2.8 MeV Fe2+, 20 MeV W2+, and 700 keV H-) with that from neutron-irradiated tungsten to identify the similarities and differences among them.

  4. Atomistic study on mixed-mode fracture mechanisms of ferrite iron interacting with coherent copper and nickel nanoclusters

    NASA Astrophysics Data System (ADS)

    Al-Motasem, Ahmed Tamer; Mai, Nghia Trong; Choi, Seung Tae; Posselt, Matthias

    2016-04-01

    The effect of copper and/or nickel nanoclusters, generally formed by neutron irradiation, on fracture mechanisms of ferrite iron was investigated by using molecular statics simulation. The equilibrium configuration of nanoclusters was obtained by using a combination of an on-lattice annealing based on Metropolis Monte Carlo method and an off-lattice relaxation by molecular dynamics simulation. Residual stress distributions near the nanoclusters were also calculated, since compressive or tensile residual stresses may retard or accelerate, respectively, the propagation of a crack running into a nanocluster. One of the nanoclusters was located in front of a straight crack in ferrite iron with a body-centered cubic crystal structure. Two crystallographic directions, of which the crack plane and crack front direction are (010)[001] and (111) [ 1 bar 10 ] , were considered, representing cleavage and non-cleavage orientations in ferrite iron, respectively. Displacements corresponding to pure opening-mode and mixed-mode loadings were imposed on the boundary region and the energy minimization was performed. It was observed that the fracture mechanisms of ferrite iron under the pure opening-mode loading are strongly influenced by the presence of nanoclusters, while under the mixed-mode loading the nanoclusters have no significant effect on the crack propagation behavior of ferrite iron.

  5. Comminuting irradiated ferritic steel

    DOEpatents

    Bauer, Roger E.; Straalsund, Jerry L.; Chin, Bryan A.

    1985-01-01

    Disclosed is a method of comminuting irradiated ferritic steel by placing the steel in a solution of a compound selected from the group consisting of sulfamic acid, bisulfate, and mixtures thereof. The ferritic steel is used as cladding on nuclear fuel rods or other irradiated components.

  6. Effects of chromium and nitrogen content on the microstructures and mechanical properties of as-cast Co-Cr-Mo alloys for dental applications.

    PubMed

    Yoda, Keita; Suyalatu; Takaichi, Atsushi; Nomura, Naoyuki; Tsutsumi, Yusuke; Doi, Hisashi; Kurosu, Shingo; Chiba, Akihiko; Igarashi, Yoshimasa; Hanawa, Takao

    2012-07-01

    The microstructure and mechanical properties of as-cast Co-(20-33)Cr-5Mo-N alloys were investigated to develop ductile Co-Cr-Mo alloys without Ni addition for dental applications that satisfy the requirements of the type 5 criteria in ISO 22674. The effects of the Cr and N contents on the microstructure and mechanical properties are discussed. The microstructures were evaluated using scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD), and electron back-scattered diffraction pattern analysis. The mechanical properties were evaluated using tensile testing. The proof strength and elongation of N-containing 33Cr satisfied the type 5 criteria in ISO 22674. ε-phase with striations was formed in the N-free (20-29)Cr alloys, while there was slight formation of ε-phase in the N-containing (20-29)Cr alloys, which disappeared in N-containing 33Cr. The lattice parameter of the γ-phase increased with increasing Cr content (i.e. N content) in the N-containing alloys, although the lattice parameter remained almost the same in the N-free alloys because of the small atomic radius difference between Co and Cr. Compositional analyses by EDS and XRD revealed that in the N-containing alloys Cr and Mo were concentrated in the cell boundary, which became enriched in N, stabilizing the γ-phase. The mechanical properties of the N-free alloys were independent of the Cr content and showed low strength and limited elongation. Strain-induced martensite was formed in all the N-free alloys after tensile testing. On the other hand, the proof strength, ultimate tensile strength, and elongation of the N-containing alloys increased with increasing Cr content (i.e. N content). Since formation of ε-phase after tensile testing was confirmed in the N-containing alloys the deformation mechanism may change from strain-induced martensite transformation to another form, such as twinning or dislocation slip, as the N content increases. Thus the N

  7. Changes in surface structure and concanavalin A-binding capacity of urothelium in the mouse bladder after whole-body neutron irradiation

    SciTech Connect

    Hodges, G.M.; Carr, K.E.; Hume, S.P.; Marigold, J.C.; Southgate, J.; Marshall, J.F.

    1985-01-01

    A broad overview has been compiled of the literature on the effects of radiation on urinary bladder and on selected cell surface markers that may give information on the pathobiological status of the urinary bladder urothelium. Scanning electron microscopy and immunogold labelling have been used in this study which examines the early (6h to 12 day) radiation response of the mouse urinary bladder following whole-body neutron irradiation. Experimentally, after 5 Gy neutron irradiation, changes in the urothelium include surface morphological abnormalities and enhanced concanavalin A surface binding. These changes were most obvious 1 to 5 days post-irradiation, but lessened in their extent from 5 to 12 days after treatment.

  8. Effect of thermal annealing and neutron irradiation in 6H-SiC implanted with silver at 350 °C and 600 °C

    NASA Astrophysics Data System (ADS)

    Hlatshwayo, T. T.; Malherbe, J. B.; van der Berg, N. G.; Botha, A. J.; Chakraborty, P.

    2012-02-01

    The effect of thermal annealing and neutron irradiation in 6H-SiC implanted with silver at 350 °C and 600 °C have been investigated using Rutherford backscattering spectrometry (RBS), Rutherford backscattering spectrometry in channeling mode (RBS-C) and scanning electron spectroscopy (SEM). Implantation at 600 °C and 350 °C caused the 6H-SiC to retain crystallinity. The 600 °C samples had less distortions compared to 350 °C implanted samples. Annealing of the radiation damage created during implantation is also reported. No diffusion of silver was detected after thermal annealing but a shift of the silver peak toward the surface due to thermal etching was observed. The amount of etched SiC has also been estimated by comparing the peak position before and after annealing. Similarly no diffusion was observed after low dose neutron irradiation of the samples.

  9. Accumulation and annealing of radiation defects under low-temperature electron and neutron irradiation of ODS steel and Fe-Cr alloys

    NASA Astrophysics Data System (ADS)

    Arbuzov, V. L.; Goshchitskii, B. N.; Sagaradze, V. V.; Danilov, S. E.; Kar'kin, A. E.

    2010-10-01

    The processes of accumulation and annealing of radiation defects at low-temperature (77 K) electron and neutron irradiation and their effect on the physicomechanical properties of Fe-Cr alloys and oxide dispersion strengthened (ODS) steel have been studied. It has been shown that the behavior of radiation defects in ODS steel and Fe-Cr alloys is qualitatively similar. Above 250 K, radiation-induced processes of the solid solution decomposition become conspicuous. These processes are much less pronounced in ODS steel because of specific features of its microstructure. Processes related to the overlapping of displacement cascades under neutron irradiation have been considered. It has been shown that, in this case, it is the increase in the size of vacancy clusters, rather than the growth of their concentration, that is prevailing. Possible mechanisms of the radiation hardening of the ODS steel and the Fe-13Cr alloy upon irradiation and subsequent annealing have been discussed.

  10. Controllability of depth dose distribution for neutron capture therapy at the Heavy Water Neutron Irradiation Facility of Kyoto University Research Reactor.

    PubMed

    Sakurai, Yoshinori; Kobayashi, Tooru

    2002-10-01

    The updating construction of the Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor has been performed from November 1995 to March 1996 mainly for the improvement in neutron capture therapy. On the performance, the neutron irradiation modes with the variable energy spectra from almost pure thermal to epi-thermal neutrons became available by the control of the heavy-water thickness in the spectrum shifter and by the open-and-close of the cadmium and boral thermal neutron filters. The depth distributions of thermal, epi-thermal and fast neutron fluxes were measured by activation method using gold and indium, and the depth distributions of gamma-ray absorbed dose rate were measured using thermo-luminescent dosimeter of beryllium oxide for the several irradiation modes. From these measured data, the controllability of the depth dose distribution using the spectrum shifter and the thermal neutron filters was confirmed.

  11. Observation of the crossover from two-gap to single-gap superconductivity through specific heat measurements in neutron-irradiated MgB2.

    PubMed

    Putti, M; Affronte, M; Ferdeghini, C; Manfrinetti, P; Tarantini, C; Lehmann, E

    2006-02-24

    We report specific heat measurements on neutron-irradiated MgB2 samples, for which the critical temperature is lowered to 8.7 K, but the superconducting transition remains extremely sharp, indicative of a defect structure extremely homogeneous. Our results evidence the presence of two superconducting gaps in the temperature range above 21 K, while single-gap superconductivity is well established as a bulk property, not associated with local disorder fluctuations, when Tc decreases to 11 K.

  12. Investigation of X-ray spectral response of D-T fusion produced neutron irradiated PIPS detectors for plasma X-ray diagnostics

    NASA Astrophysics Data System (ADS)

    Vigneshwara Raja, P.; Narasimha Murty, N. V. L.; Rao, C. V. S.; Abhangi, Mitul

    2015-10-01

    This paper describes the fusion-produced neutron irradiation induced changes in the X-ray spectral response of commercially available Passivated Implanted Planar Silicon (PIPS) detectors using the accelerator based D-T generator. After 14.1 MeV neutron irradiation up to a fluence of 3.6× 1010 n/cm2, the energy resolution (i.e. FWHM) of the detectors at room temperature is found to degrade by about 3.8 times that of the pre-irradiated value. From the X-ray spectral characteristics, it has been observed that the room temperature spectral response of PIPS detectors is too poor even at low neutron fluences. Irradiation is also carried out with Am-Be neutron source for studying the effect of scattered neutrons from the reactor walls on the detector performance. Comparative studies of the damage caused by 14.1 MeV neutrons and Am-Be source produced neutrons at the same neutron fluence are carried out by analyzing the irradiated detector characteristics. The degradation in the energy resolution of the detectors is attributed to the radiation induced changes in the detector leakage current. No considerable changes in the full depletion voltage and the effective doping concentration up to the neutron fluence of 3.6× 1010 n/cm2, are observed from the measured C-V characteristics. Partial recovery of the neutron irradiated detector characteristics is discussed.

  13. FISSION NEUTRON IRRADIATION EFFECT ON INTERLAMINAR SHEAR STRENGTH OF CYANATE ESTER RESIN GFRP AT RT AND 77 K

    SciTech Connect

    Nishimura, A.; Izumi, Y.; Nishijima, S.; Hemmi, T.; Koizumi, K.; Takeuchi, T.; Shikama, T.

    2010-04-08

    A glass fiber reinforced plastic (GFRP) with cyanate ester resin was fabricated and neutron irradiation tests up to 1x10{sup 22} n/m{sup 2} of fast neutron with over 0.1 MeV energy were carried out in fission reactor. The fabrication process of cyanate ester GFRP was established and a collaboration network to perform investigations on irradiation effect of superconducting magnet materials was constructed. Three kinds of samples were fabricated. The first was CTD403 GFRP made by NIFS, the second was (cyanate ester+epoxy) GFRP provided by Toshiba, and the last was CTD403 GFRP made by Toshiba. The irradiation was carried out at JRR-3 in Japan Atomic Energy Agency using Rabbit capsules.After the irradiation, short beam tests were conducted at room temperature and 77 K and interlaminar shear strength (ILSS) was evaluated. The irradiation of 1x10{sup 21} n/m{sup 2} increased ILSS a little but 1x10{sup 22} n/m{sup 2} irradiation decreased ILSS to around 50 MPa. These tendencies were observed in all three kinds of GFRPs.

  14. Effect of neutron irradiation and postradiation annealing on the microstructure and properties of an Al-Mg-Si alloy

    NASA Astrophysics Data System (ADS)

    Maksimkin, O. P.; Tsai, K. V.; Rofman, O. V.; Sil'nyagina, N. S.

    2016-09-01

    The effect of long-term neutron irradiation and postradiation thermal-induced aging on the microstructure and mechanical properties of an aluminum-based reactor Al-Mg-Si alloy grade SAV-1 has been studied. The material under study is the shell of an automatic fine-control rod used to control the reactivity of the core of a VVR-K research reactor. Successive 1-h annealings of specimens of the SAV-1 alloy irradiated to doses of 0.001 and 5 dpa in the temperature range of 100-550°C have been carried out. The evolution of the fine structure of the material and changes in its mechanical characteristics have been studied. The phenomenon of the acceleration of the aging of the SAV-1 alloy under the effect of a high neutron fluence at an irradiation temperature of 80°C has been observed, which involves the formation of numerous lineage (stitch) Guinier-Preston zones in the alloy. It has been shown that the strength characteristics of the SAV-1 alloy depend significantly on the degree of its radiation- and thermal-induced aging.

  15. Development of microstructure and irradiation hardening of Zircaloy during low dose neutron irradiation at nominally 358 C

    SciTech Connect

    Cockeram, Brian V; Smith, Richard W; Leonard, Keith J; Byun, Thak Sang; Snead, Lance Lewis

    2011-01-01

    Wrought Zircaloy-2 and Zircaloy-4 were neutron irradiated at nominally 358 C in the high flux isotope reactor (HFIR) at relatively low neutron fluences between 5.8 1022 and 2.9 1025 n/m2 (E > 1 MeV). The irradiation hardening and change in microstructure were characterized following irradiation using tensile testing and examinations of microstructure using Analytical Electron Microscopy (AEM). Small increments of dose (0.0058, 0.11, 0.55, 1.08, and 2.93 1025 n/m2) were used in the range where the saturation of irradiation hardening is typically observed so that the role of microstructure evolution and hai loop formation on irradiation hardening could be correlated. An incubation dose between 5.8 1023 and 1.1 1024 n/m2 was needed for loop nucleation to occur that resulted in irradiation hardening. Increases in yield strength were consistent with previous results in this temperature regime, and as expected less irradiation hardening and lower hai loop number density values than those generally reported in literature for irradiations at 260 326 C were observed. Unlike previous lower temperature data, there is evidence in this study that the irradiation hardening can decrease with dose over certain ranges of fluence. Irradiation induced voids were observed in very low numbers in the Zircaloy-2 materials at the highest fluence.

  16. Continued investigation of kinetic aspects of bone mineral metabolism. [determining body calcium by measuring argon after neutron irradiation

    NASA Technical Reports Server (NTRS)

    Palmer, H. E.

    1974-01-01

    The total body calcium in humans was determined by measuring expired Ar-37 after neutron irradiation. The excretion of Ar-37 from humans was found to be much slower than the excretion from rats and dogs, and to be related to the age of a person. A study of the uniformity of the Ar-37 production throughout the thickness of the body was studied using phantoms. The results indicate that it should be possible to obtain a uniformity within plus or minus 3% for the production of Ar-37 per unit of calcium by using a bilateral irradiation. New low background, large volume proportional counters were developed and constructed, for more sensitive measurement of Ar-37 in the expired air from patients. A new irradiation enclosure was developed for measuring total body calcium in rats by the Ar-37 method. With this enclosure the Ar-37 production per gram of calcium is constant with a standard deviation of plus or minus 2.8% for any size rat between 100 and 500 grams. The use of Na-22 as measure of bone replacement in the fractured femur of a dog was not successful.

  17. High dose neutron irradiations of Hi-Nicalon Type S silicon carbide composites, Part 1: Microstructural evaluations

    SciTech Connect

    Perez-Bergquist, Alex G.; Nozawa, Takashi; Shih, Chunghao Phillip; Leonard, Keith J.; Snead, Lance Lewis; Katoh, Yutai

    2014-07-01

    Over the past decade, significant progress has been made in the development of silicon carbide (SiC) composites, composed of near-stoichiometric SiC fibers embedded in a crystalline SiC matrix, to the point that such materials can now be considered nuclear grade. Recent neutron irradiation studies of Hi-Nicalon Type S SiC composites showed excellent radiation response at damage levels of 30-40 dpa at temperatures of 300-800 °C. However, more recent studies of these same fiber composites irradiated to damage levels of >70 dpa at similar temperatures showed a marked decrease in ultimate flexural strength, particularly at 300 °C. Here, electron microscopy is used to analyze the microstructural evolution of these irradiated composites in order to investigate the cause of the degradation. While minimal changes were observed in Hi-Nicalon Type S SiC composites irradiated at 800 °C, substantial microstructural evolution is observed in those irradiated at 300° C. Furthermore, carbonaceous particles in the fibers grew by 25% compared to the virgin case, and severe cracking occurred at interphase layers.

  18. High Dose Neutron Irradiation of Hi-Nicalon Type S Silicon Carbide Composites, Part 2. Mechanical and Physical Properties

    DOE PAGESBeta

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao Phillip; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wallace D; Snead, Lance Lewis

    2015-01-07

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573–1073 K. Likewise, the material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating themore » irradiation temperature, but only to a limited extent. Moreover, the observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.« less

  19. Neutron-transmuted carbon-14 in neutron-irradiated GaN: Compensation of DX-like center

    SciTech Connect

    Ida, T.; Oga, T.; Kuriyama, K.; Kushida, K.; Xu, Q.; Fukutani, S.

    2013-12-04

    The transmuted-C related luminescence and net carrier concentration are studied by combining photoluminescence, liquid scintillation, and Raman scattering. GaN single crystal films grown by metalorganic-vapor-phase epitaxy are irradiated with fast and thermal neutrons at fluxes of 3.9 × 10{sup 13} cm{sup −2}s{sup −1} and 8.15 × 10{sup 13} cm{sup −2}s{sup −1}, respectively. Irradiation time is 48 hours. The calculated {sup 72}Ge and {sup 14}C concentrations are 1.24 × 10{sup 18} cm{sup −3} and 1.13 × 10{sup 18} cm{sup −3}, respectively. The transmuted {sup 14}C is detected by the liquid scintillation method to survey β-rays emitted in the process of {sup 14}C decays from {sup 14}N. Tritium ({sup 3}H) is also emitted by a (n,t) reaction of {sup 14}N due to the neutron irradiation above 4.5 MeV. Photoluminescence relating to C, DX-like center of Ge and yellow luminescence band are observed in 1000 °C annealed NTD-GaN. The free electron concentration estimated from Raman scattering is 4.97 × 10{sup 17} cm{sup −3}. This value is lower than that from the transmuted Ge concentration, suggesting the compensation due to the transmuted {sup 14}C acceptors.

  20. Fission Neutron Irradiation Effect on Interlaminar Shear Strength of Cyanate Ester Resin Gfrp at RT and 77 K

    NASA Astrophysics Data System (ADS)

    Nishimura, A.; Izumi, Y.; Nishijima, S.; Hemmi, T.; Koizumi, K.; Takeuchi, T.; Shikama, T.

    2010-04-01

    A glass fiber reinforced plastic (GFRP) with cyanate ester resin was fabricated and neutron irradiation tests up to 1×1022 n/m2 of fast neutron with over 0.1 MeV energy were carried out in fission reactor. The fabrication process of cyanate ester GFRP was established and a collaboration network to perform investigations on irradiation effect of superconducting magnet materials was constructed. Three kinds of samples were fabricated. The first was CTD403 GFRP made by NIFS, the second was (cyanate ester+epoxy) GFRP provided by Toshiba, and the last was CTD403 GFRP made by Toshiba. The irradiation was carried out at JRR-3 in Japan Atomic Energy Agency using Rabbit capsules. After the irradiation, short beam tests were conducted at room temperature and 77 K and interlaminar shear strength (ILSS) was evaluated. The irradiation of 1×1021 n/m2 increased ILSS a little but 1×1022 n/m2 irradiation decreased ILSS to around 50 MPa. These tendencies were observed in all three kinds of GFRPs.

  1. The measurement of material degradation in neutron irradiated Mn-Mo-Ni low alloy steels using magnetic techniques

    NASA Astrophysics Data System (ADS)

    Chang, Kee-Ok; Chi, Se-Hwan; Kim, Taek-Soo; Kim, Byoung-Chul; Lee, Sam-Lai

    1999-12-01

    To examine the application of magnetic method to the evaluation of radiation damage and thermal recovery in Mn-Mo-Ni reactor pressure vessel(RPV) steels, changes in the magnetic parameters and Vickers microhardness(Hv) due to neutron irradiation and heat treatment were measured and compared for RPV surveillance specimens which were irradiated to the neutron fluence of 2.4×1019n/cm2 (E⩾1.0 MeV) in a typical pressurized water reactor environment at 288 °C. Results show that the coercivity(Hc) increased due to irradiation, whereas susceptibility and Barkhausen noise energy(BNE) decreased. Saturation magnetization(Ms) remained unchanged while Vickers microhardness increased. For isothermally heat treated specimens, both the magnetic parameters and Vickers microhardness returned to the unirradiated condition: Thus, the BNE and susceptibility increased while the coercivity and Vickers microhardness decreased. From the comparison of irradiated base metal and weld metal, it is found that the susceptibility and BNE of the weld metal were smaller than those of base metal and the microhardness and coercivity of weld metal were larger than those of base metal. All these consistent changes in magnetic parameters show a possibility that magnetic techniques may be used for the evaluation of material degradation.

  2. Spectrum evaluation at the filter-modified neutron irradiation field for neutron capture therapy in Kyoto University Research Reactor

    NASA Astrophysics Data System (ADS)

    Sakurai, Yoshinori; Kobayashi, Tooru

    2004-10-01

    The Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor (KUR-HWNIF) was updated in March 1996, mainly to improve the facility for neutron capture therapy (NCT). In this facility, neutron beams with various energy spectra, from almost pure thermal to epithermal, are available. The evaluation of the neutron energy spectra by multi-activation-foil method was performed as a series of the facility characterization. The spectra at the normal irradiation position were evaluated for the combinations of heavy-water thickness of the spectrum shifter and the open-close condition of the cadmium and boral filters. The initial spectra were made mainly using a two-dimensional transport code, and the final spectra were obtained using an adjusting code. For the verification of the evaluated spectra, simulation calculations using a phantom were performed on the assumption of NCT-clinical-irradiation conditions. It resulted that the calculated data for the depth neutron-flux distributions were in good agreement with the experimental ones.

  3. Comparison of pka energy spectra, gas-atom production and damage energy deposition in neutron irradiation at various facilities

    NASA Astrophysics Data System (ADS)

    Nishiguchi, R.; Shimomura, Y.; Hahn, P. A.; Guinan, M. W.; Kiritani, M.

    1991-03-01

    By dividing neutron-energy spectrum into four energy groups, (I) <10 eV, (II) 10 eV to 0.1 MeV, (III) 0.1 MeV to 10 MeV and (IV) > 10 MeV, contributions to damage parameters (PKA spectrum, damage energy and gas-atom production) from each of the energy group were calculated for neutron irradiations at various facilities with the SPECTER code developed by Greenwood and Smither [1]. The normalized PKA spectra and the gas-atom productions were compared to examine differences in damage parameters. Such comparisons were carried out among (1) irradiations at various positions in different fission reactors (i.e. KUR, JOYO and FFTF-MOTA), and among (2) those at various fission reactors. Damage parameters were also calculated at STARFIRE fusion reactor and RTNS-II. A possible method to correlate damages at different fission reactors is discussed. It is suggested that damages in fusion reactor can be simulated by the superposition of irradiations with fission and D-T neutrons.

  4. Hardening and microstructural evolution in A533B steels under neutron irradiation and a direct comparison with electron irradiation

    NASA Astrophysics Data System (ADS)

    Fujii, K.; Nakata, H.; Fukuya, K.; Ohkubo, T.; Hono, K.; Nagai, Y.; Hasegawa, M.; Yoshiie, T.

    2010-05-01

    A533B steels irradiated at 290 °C up to 10 mdpa in the Kyoto University Reactor were examined by hardness, positron annihilation and atom probe measurements. Dose dependent irradiation hardening and formation of Cu-rich clusters were confirmed in medium Cu (0.12% and 0.16%Cu) steels whereas neither hardening nor cluster formation was detected in low Cu (0.03%Cu) steel. No microvoids were formed in any of the steels. Post-irradiation annealing in medium Cu steels revealed that the hardening recovery at temperatures above 350-400 °C could be attributed to compositional changes and dissociation of the Cu-rich clusters. Compared to electron irradiation at almost the same dose and dose rate, KUR irradiation caused almost the same hardening and produced Cu-rich clusters, more solute-enriched with larger size and lower density. Considering lower production of freely-migrating vacancies in neutron irradiation, the results suggested that cascades enhance the formation of Cu-rich clusters.

  5. Pixel pitch and particle energy influence on the dark current distribution of neutron irradiated CMOS image sensors.

    PubMed

    Belloir, Jean-Marc; Goiffon, Vincent; Virmontois, Cédric; Raine, Mélanie; Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Molina, Romain; Magnan, Pierre; Gilard, Olivier

    2016-02-22

    The dark current produced by neutron irradiation in CMOS Image Sensors (CIS) is investigated. Several CIS with different photodiode types and pixel pitches are irradiated with various neutron energies and fluences to study the influence of each of these optical detector and irradiation parameters on the dark current distribution. An empirical model is tested on the experimental data and validated on all the irradiated optical imagers. This model is able to describe all the presented dark current distributions with no parameter variation for neutron energies of 14 MeV or higher, regardless of the optical detector and irradiation characteristics. For energies below 1 MeV, it is shown that a single parameter has to be adjusted because of the lower mean damage energy per nuclear interaction. This model and these conclusions can be transposed to any silicon based solid-state optical imagers such as CIS or Charged Coupled Devices (CCD). This work can also be used when designing an optical imager instrument, to anticipate the dark current increase or to choose a mitigation technique.

  6. High dose neutron irradiations of Hi-Nicalon Type S silicon carbide composites, Part 1: Microstructural evaluations

    DOE PAGESBeta

    Perez-Bergquist, Alex G.; Nozawa, Takashi; Shih, Chunghao Phillip; Leonard, Keith J.; Snead, Lance Lewis; Katoh, Yutai

    2014-07-01

    Over the past decade, significant progress has been made in the development of silicon carbide (SiC) composites, composed of near-stoichiometric SiC fibers embedded in a crystalline SiC matrix, to the point that such materials can now be considered nuclear grade. Recent neutron irradiation studies of Hi-Nicalon Type S SiC composites showed excellent radiation response at damage levels of 30-40 dpa at temperatures of 300-800 °C. However, more recent studies of these same fiber composites irradiated to damage levels of >70 dpa at similar temperatures showed a marked decrease in ultimate flexural strength, particularly at 300 °C. Here, electron microscopy ismore » used to analyze the microstructural evolution of these irradiated composites in order to investigate the cause of the degradation. While minimal changes were observed in Hi-Nicalon Type S SiC composites irradiated at 800 °C, substantial microstructural evolution is observed in those irradiated at 300° C. Furthermore, carbonaceous particles in the fibers grew by 25% compared to the virgin case, and severe cracking occurred at interphase layers.« less

  7. The role of nickel in radiation damage of ferritic alloys

    DOE PAGESBeta

    Osetskiy, Yury N.; Anento, Napoleon; Serra, Anna; Terentyev, Dmitry

    2014-11-26

    According to the modern theory damage evolution under neutron irradiation depends on the fraction of self interstitial atoms (SIAs) produced in the form of one-dimensionally (1-D) glissile clusters. These clusters, having a low interaction cross-section with other defects, sink mainly on grain boundaries and dislocations creating the so-called production bias. It is known empirically that addition of certain alloying elements affect many radiation effects, including swelling, however the mechanisms are unknown in many cases. In this paper we report the results of an extensive multi-technique atomistic level modeling of SIA clusters mobility in bcc Fe-Ni alloys with Ni content frommore » 0.8 to 10 at.%. We have found that Ni interacts strongly with periphery of clusters affecting their mobility. The total effect is defined by all Ni atoms interacting with the cluster at the same time and can be significant even in low-Ni alloys. Thus 1nm (37SIAs) cluster is practically immobile at T < 500K in the Fe-0.8at.% Ni alloy. Increasing cluster size and Ni content enhance cluster immobilization. Furthermore, this effect should have quite broad consequences in swelling rate, matrix damage accumulation, radiation induced hardening, etc. and the results obtained help in better understanding and prediction of radiation effects in Fe-Ni ferritic alloys.« less

  8. The role of nickel in radiation damage of ferritic alloys

    SciTech Connect

    Osetskiy, Yury N.; Anento, Napoleon; Serra, Anna; Terentyev, Dmitry

    2014-11-26

    According to the modern theory damage evolution under neutron irradiation depends on the fraction of self interstitial atoms (SIAs) produced in the form of one-dimensionally (1-D) glissile clusters. These clusters, having a low interaction cross-section with other defects, sink mainly on grain boundaries and dislocations creating the so-called production bias. It is known empirically that addition of certain alloying elements affect many radiation effects, including swelling, however the mechanisms are unknown in many cases. In this paper we report the results of an extensive multi-technique atomistic level modeling of SIA clusters mobility in bcc Fe-Ni alloys with Ni content from 0.8 to 10 at.%. We have found that Ni interacts strongly with periphery of clusters affecting their mobility. The total effect is defined by all Ni atoms interacting with the cluster at the same time and can be significant even in low-Ni alloys. Thus 1nm (37SIAs) cluster is practically immobile at T < 500K in the Fe-0.8at.% Ni alloy. Increasing cluster size and Ni content enhance cluster immobilization. Furthermore, this effect should have quite broad consequences in swelling rate, matrix damage accumulation, radiation induced hardening, etc. and the results obtained help in better understanding and prediction of radiation effects in Fe-Ni ferritic alloys.

  9. Effect of neutron irradiation on defect evolution in Ti3SiC2 and Ti2AlC

    NASA Astrophysics Data System (ADS)

    Tallman, Darin J.; He, Lingfeng; Garcia-Diaz, Brenda L.; Hoffman, Elizabeth N.; Kohse, Gordon; Sindelar, Robert L.; Barsoum, Michel W.

    2016-01-01

    Herein we report on the characterization of defects formed in polycrystalline Ti3SiC2 and Ti2AlC samples exposed to neutron irradiation - up to 0.1 displacements per atom (dpa) at 350 ± 40 °C or 695 ± 25 °C, and up to 0.4 dpa at 350 ± 40 °C. Black spots are observed in both Ti3SiC2 and Ti2AlC after irradiation to both 0.1 and 0.4 dpa at 350 °C. After irradiation to 0.1 dpa at 695 °C, small basal dislocation loops, with a Burgers vector of b = 1/2 [0001] are observed in both materials. At 9 ± 3 and 10 ± 5 nm, the loop diameters in the Ti3SiC2 and Ti2AlC samples, respectively, were comparable. At 1 × 1023 loops/m3, the dislocation loop density in Ti2AlC was ≈1.5 orders of magnitude greater than in Ti3SiC2, at 3 × 1021 loops/m3. After irradiation at 350 °C, extensive microcracking was observed in Ti2AlC, but not in Ti3SiC2. The room temperature electrical resistivities increased as a function of neutron dose for all samples tested, and appear to saturate in the case of Ti3SiC2. The MAX phases are unequivocally more neutron radiation tolerant than the impurity phases TiC and Al2O3. Based on these results, Ti3SiC2 appears to be a more promising MAX phase candidate for high temperature nuclear applications than Ti2AlC.

  10. In vivo skin leptin modulation after 14 MeV neutron irradiation: a molecular and FT-IR spectroscopic study.

    PubMed

    Cestelli Guidi, M; Mirri, C; Fratini, E; Licursi, V; Negri, R; Marcelli, A; Amendola, R

    2012-09-01

    This paper discusses gene expression changes in the skin of mice treated by monoenergetic 14 MeV neutron irradiation and the possibility of monitoring the resultant lipid depletion (cross-validated by functional genomic analysis) as a marker of radiation exposure by high-resolution FT-IR (Fourier transform infrared) imaging spectroscopy. The irradiation was performed at the ENEA Frascati Neutron Generator (FNG), which is specifically dedicated to biological samples. FNG is a linear electrostatic accelerator that produces up to 1.0 × 10(11) 14-MeV neutrons per second via the D-T nuclear reaction. The functional genomic approach was applied to four animals for each experimental condition (unirradiated, 0.2 Gy irradiation, or 1 Gy irradiation) 6 hours or 24 hours after exposure. Coregulation of a subclass of keratin and keratin-associated protein genes that are physically clustered in the mouse genome and functionally related to skin and hair follicle proliferation and differentiation was observed. Most of these genes are transiently upregulated at 6 h after the delivery of the lower dose delivered, and drastically downregulated at 24 h after the delivery of the dose of 1 Gy. In contrast, the gene coding for the leptin protein was consistently upregulated upon irradiation with both doses. Leptin is a key protein that regulates lipid accumulation in tissues, and its absence provokes obesity. The tissue analysis was performed by monitoring the accumulation and the distribution of skin lipids using FT-IR imaging spectroscopy. The overall picture indicates the differential modulation of key genes during epidermis homeostasis that leads to the activation of a self-renewal process at low doses of irradiation.

  11. Neutron irradiation damage of nuclear graphite studied by high-resolution transmission electron microscopy and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Krishna, R.; Jones, A. N.; McDermott, L.; Marsden, B. J.

    2015-12-01

    Nuclear graphite components are produced from polycrystalline artificial graphite manufacture from a binder and filler coke with approximately 20% porosity. During the operational lifetime, nuclear graphite moderator components are subjected to fast neutron irradiation which contributes to the change of material and physical properties such as thermal expansion co-efficient, young's modulus and dimensional change. These changes are directly driven by irradiation-induced changes to the crystal structure as reflected through the bulk microstructure. It is therefore of critical importance that these irradiation changes and there implication on component property changes are fully understood. This work examines a range of irradiated graphite samples removed from the British Experimental Pile Zero (BEPO) reactor; a low temperature, low fluence, air-cooled Materials Test Reactor which operated in the UK. Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) have been employed to characterise the effect of increased irradiation fluence on graphite microstructure and understand low temperature irradiation damage processes. HRTEM confirms the structural damage of the crystal lattice caused by irradiation attributed to a high number of defects generation with the accumulation of dislocation interactions at nano-scale range. Irradiation-induced crystal defects, lattice parameters and crystallite size compared to virgin nuclear graphite are characterised using selected area diffraction (SAD) patterns in TEM and Raman Spectroscopy. The consolidated 'D'peak in the Raman spectra confirms the formation of in-plane point defects and reflected as disordered regions in the lattice. The reduced intensity and broadened peaks of 'G' and 'D' in the Raman and HRTEM results confirm the appearance of turbulence and disordering of the basal planes whilst maintaining their coherent layered graphite structure.

  12. Effect of neutron irradiation on defect evolution in Ti3SiC2 and Ti2AlC

    DOE PAGESBeta

    Tallman, Darin J.; He, Lingfeng; Garcia-Diaz, Brenda L.; Hoffman, Elizabeth N.; Kohse, Gordon; Sindelar, Robert L.; Barsoum, Michel W.

    2015-10-23

    Here, we report on the characterization of defects formed in polycrystalline Ti3SiC2 and Ti2AlC samples exposed to neutron irradiation – up to 0.1 displacements per atom (dpa) at 350 ± 40 °C or 695 ± 25 °C, and up to 0.4 dpa at 350 ± 40 °C. Black spots are observed in both Ti3SiC2 and Ti2AlC after irradiation to both 0.1 and 0.4 dpa at 350 °C. After irradiation to 0.1 dpa at 695 °C, small basal dislocation loops, with a Burgers vector of b = 1/2 [0001] are observed in both materials. At 9 ± 3 and 10 ±more » 5 nm, the loop diameters in the Ti3SiC2 and Ti2AlC samples, respectively, were comparable. At 1 × 1023 loops/m3, the dislocation loop density in Ti2AlC was ≈1.5 orders of magnitude greater than in Ti3SiC2, at 3 x 1021 loops/m3. After irradiation at 350 °C, extensive microcracking was observed in Ti2AlC, but not in Ti3SiC2. The room temperature electrical resistivities increased as a function of neutron dose for all samples tested, and appear to saturate in the case of Ti3SiC2. The MAX phases are unequivocally more neutron radiation tolerant than the impurity phases TiC and Al2O3. Based on these results, Ti3SiC2 appears to be a more promising MAX phase candidate for high temperature nuclear applications than Ti2AlC.« less

  13. Impedance calculation for ferrite inserts

    SciTech Connect

    Breitzmann, S.C.; Lee, S.Y.; Ng, K.Y.; /Fermilab

    2005-01-01

    Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. They study the narrowband longitudinal impedance of these ferrite inserts. they find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. They also provide a recipe for attaining a truly passive space charge impedance compensation and avoiding narrowband microwave instabilities.

  14. Continuous gamma and neutron irradiation at low doses can increase the number of stromal progenitor cell (CFU-F) in mouse bone marrow

    NASA Astrophysics Data System (ADS)

    Domaratskaya, E. I.; Tsetlin, V. V.; Bueverova, E. I.; Payushina, O. I.; Butorina, N. N.; Khrushchov, N. G.; Starostin, V. I.

    Experimental groups of male and female F1 (CBA × C57Bl/6) mice at the age of 3-4 months were exposed for 10 days to gamma irradiation (total dose 1.5 cGy, dose rate 0.15 cGy/day) or neutron irradiation (neutrons at average energy of 4.5 MeV at a total neutron flux ranging from 10 5 to 10 6 cm -2 and neutron flux density from 1 to 30 cm -2 s -1). These radiation doses were chosen so as to correspond to those received aboard spacecraft. [Mitrikas, V.G., Tsetlin, V.V., 2000. Radiation control onboard the MIR orbital manned station during the 22th solar cycle. Kosm. Issled. 38(2), 113-118.] Gamma irradiation stimulated the proliferation of femoral CFU-F, and their number increased by a factor of 1.5-4.5. The ectopic marrow grafts from γ-irradiated donors also increased in size. However, no changes in CFU-S proliferation rate and their number were observed. Neutron irradiation at a total absorbed dose of 2 × 10 -1 cGy (total neutron flux 2.8 × 10 7 cm -2) produced a 1.5-3-fold increase in the number of femoral CFU-F, but that of CFU-S remained unchanged. At a lower total absorbed dose 0.82 × 10 -2 cGy, total neutron flux 1.3 × 10 6 cm -2, the number of CFU-F remained at the control level. Therefore, the effect of radiation hormesis caused by neutron irradiation was observed at doses much lower than those of gamma irradiation.

  15. Determining the shear fracture properties of HIP joints of reduced-activation ferritic/martensitic steel by a torsion test

    NASA Astrophysics Data System (ADS)

    Nozawa, Takashi; Noh, Sanghoon; Tanigawa, Hiroyasu

    2012-08-01

    Hot isostatic pressing (HIP) is a key technology used to fabricate a first wall with cooling channels for the fusion blanket system utilizing a reduced-activation ferritic/martensitic steel. To qualify the HIPped components, small specimen test techniques are beneficial not only to evaluate the thin-wall cooling channels containing the HIP joint but also to use in neutron irradiation studies. This study aims to develop the torsion test method with special emphasis on providing a reasonable and comprehensive method to determine interfacial shear properties of HIP joints during the torsional fracture process. Torsion test results identified that the torsion process shows yield of the base metal followed by non-elastic deformation due to work hardening of the base metal. By considering this work hardening issue, we propose a reasonable and realistic solution to determine the torsional yield shear stress and the ultimate torsional shear strength of the HIPped interface. Finally, a representative torsion fracture process was identified.

  16. Associations of Pd, U and Ag in the SiC layer of neutron-irradiated TRISO fuel

    NASA Astrophysics Data System (ADS)

    Lillo, T. M.; van Rooyen, I. J.

    2015-05-01

    Knowledge of the associations and composition of fission products in the neutron irradiated SiC layer of high-temperature gas reactor TRISO fuel is important to the understanding of various aspects of fuel performance that presently are not well understood. Recently, advanced characterization techniques have been used to examine fuel particles from the Idaho National Laboratory's AGR-1 experiment. Nano-sized Ag and Pd precipitates were previously identified in grain boundaries and triple points in the SiC layer of irradiated TRISO nuclear fuel. Continuation of this initial research is reported in this paper and consists of the characterization of a relatively large number of nano-sized precipitates in three areas of the SiC layer of a single irradiated TRISO nuclear fuel particle using standardless EDS analysis on focused ion beam-prepared transmission electron microscopy samples. Composition and distribution analyses of these precipitates, which were located on grain boundaries, triple junctions and intragranular precipitates, revealed low levels, generally <10 atomic %, of palladium, silver and/or uranium with palladium being the most common element found. Palladium by itself, or associated with either silver or uranium, was found throughout the SiC layer. A small number of precipitates on grain boundaries and triple junctions were found to contain only silver or silver in association with palladium while uranium was always associated with palladium but never found by itself or in association with silver. Intergranular precipitates containing uranium were found to have migrated ∼23 μm along a radial direction through the 35 μm thick SiC coating during the AGR-1 experiment while silver-containing intergranular precipitates were found at depths up to ∼24 μm in the SiC layer. Also, Pd-rich, nano-precipitates (∼10 nm in diameter), without evidence for the presence of either Ag or U, were revealed in intragranular regions throughout the SiC layer. Because not

  17. Associations of Pd, U and Ag in the SiC layer of neutron-irradiated TRISO fuel

    SciTech Connect

    Lillo, Thomas; Rooyen, Isabella Van

    2015-05-01

    Knowledge of the associations and composition of fission products in the neutron irradiated SiC layer of high-temperature gas reactor TRISO fuel is important to the understanding of various aspects of fuel performance that presently are not well understood. Recently, advanced characterization techniques have been used to examine fuel particles from the Idaho National Laboratory’s AGR-1 experiment. Nano-sized Ag and Pd precipitates were previously identified in grain boundaries and triple points in the SiC layer of irradiated TRISO nuclear fuel. Continuation of this initial research is reported in this paper and consists of the characterization of a relatively large number of nano-sized precipitates in three areas of the SiC layer of a single irradiated TRISO nuclear fuel particle using standardless EDS analysis on focused ion beam-prepared transmission electron microscopy samples. Composition and distribution analyses of these precipitates, which were located on grain boundaries, triple junctions and intragranular precipitates, revealed low levels, generally <10 atomic %, of palladium, silver and/or uranium with palladium being the most common element found. Palladium by itself, or associated with either silver or uranium, was found throughout the SiC layer. A small number of precipitates on grain boundaries and triple junctions were found to contain only silver or silver in association with palladium while uranium was always associated with palladium but never found by itself or in association with silver. Intergranular precipitates containing uranium were found to have migrated ~23 μm along a radial direction through the 35 μm thick SiC coating during the AGR-1 experiment while silver-containing intergranular precipitates were found at depths up to ~24 μm in the SiC layer. Also, Pd-rich, nano-precipitates (~10 nm in diameter), without evidence for the presence of either Ag or U, were revealed in intragranular regions throughout the SiC layer. Because not all

  18. NEUTRON-IRRADIATED STRUCTURES

    DOEpatents

    Ashley, E.L.; Ashley, J.W.; Bowker, H.W.; Hall, R.H.; Kendall, J.W.

    1959-02-01

    A moderator structure is described for a nuclear reactor of the heterogensous type wherein a large mass of moderator is provided with channels therethrough for the introduction of uranium serving as nuclear fuel and for the passage of a cooling fluid. The structure is comprised of blocks of moderator material in superposed horizontal layers, the blocks of each layer being tied together with spaces between them and oriented to have horizontal Wigner growth. The ties are strips of moderator material, the same as the blocks, with transverse Wigner growth, disposed horizontally along lines crossing at vertical axes of the blocks. The blocks are preferably rectangular with a larger or length dimension transverse to the directions of Wiguer growth and are stood on end to provide for horizontal growth.

  19. The enhancement of neutron irradiation of HeLa-S cervix carcinoma cells by cell-nucleus-addressed deca-p-boronophenylalanine.

    PubMed

    Braun, Klaus; Wolber, Gerd; Waldeck, Waldemar; Pipkorn, Rüdiger; Jenne, Jürgen; Rastert, Ralf; Ehemann, Volker; Eisenmenger, Andreas; Corban-Wilhelm, Heike; Braun, Isabell; Heckl, Stefan; Debus, Jürgen

    2003-06-01

    Boron neutron capture therapy (BNCT) is an experimental treatment modality which depends on a sufficient cellular uptake of Boron ((10)B) followed by an exposure to a thermal neutron beam from a nuclear reactor. High energetic particles (4He and 7Li) are created during the neutron capture reaction and produce DNA damages, which lead to cell killing. Regarding BNCT, the short radiation range of He- and Li-particles is decisive for the distribution of (10)B. Until now, BNCT has been lacking for therapeutically effective concentrations of (10)B. Twenty-four hours after the combined use of our 'Bioshuttle'-p-borono-phenylalanine(10)-constructs ('Bioshuttle'-p-BPA(10)) and neutron-irradiation, an obvious reduction of the radiation-resistant HeLa-S cells could be observed. No cells were alive 72 h after the incubation with 'Bioshuttle'-p-BPA(10) followed by neutron irradiation. A post-mitotic cell death could be assumed based on flow cytometrical data.

  20. Positron Annihilation Lifetime Spectroscopy Study of Neutron Irradiated High Temperature Superconductors YBa2Cu3O7-δ for Application in Fusion Facilities

    NASA Astrophysics Data System (ADS)

    Veterníková, J.; Chudý, M.; Slugeň, V.; Eisterer, M.; Weber, H. W.; Sojak, S.; Petriska, M.; Hinca, R.; Degmová, J.; Sabelová, V.

    2012-02-01

    This study focuses on the crystallographic defects introduced by neutron irradiation and the resulting changes of the superconducting properties in the high temperature superconductor YBa2Cu3O7-δ. This material is considered to be most promising for magnet systems in future fusion reactors. Two different bulk samples, pure non-doped YBa2Cu3O7-δ (YBCO) and multi-seed YBa2Cu3O7-δ doped by platinum (MS2F) were studied prior to and after irradiation in the TRIGA MARK II reactor in Vienna. Neutron irradiation is responsible for a significant enhancement of the critical current densities as well as for a reduction in critical temperature. The accumulation of small open volume defects (<0.5 nm) partially causes those changes. These defects were studied by positron annihilation lifetime spectroscopy at room temperature. A high concentration of Cu-O di-vacancies was found in both samples, which increased with neutron fluence. The defect concentration was significantly reduced after a heat treatment.

  1. Development of A New Class of Fe-3Cr-W(V)Ferritic Steels for Industrial Process Applications

    SciTech Connect

    Sikka, V.J.; Jawad, M.H.

    2005-06-15

    The project, 'Development of a New Class of Fe-Cr-W(V) Ferritic Steels for Industrial Process Applications', was a Cooperative Research and Development Agreement (CRADA) between Oak Ridge National Laboratory (ORNL) and Nooter Corporation. This project dealt with improving the materials performance and fabrication for the hydrotreating reactor vessels, heat recovery systems, and other components for the petroleum and chemical industries. The petroleum and chemical industries use reactor vessels that can approach the ship weights of approximately 300 tons with vessel wall thicknesses of 3 to 8 in. These vessels are typically fabricated from Fe-Cr-Mo steels with chromium ranging from 1.25 to 12% and molybdenum from 1 to 2%. Steels in this composition have great advantages of high thermal conductivity, low thermal expansion, low cost, and properties obtainable by heat treatment. With all of the advantages of Fe-Cr-Mo steels, several issues are faced in design and fabrication of vessels and related components. These issues include the following: (1) low strength properties of current alloys require thicker sections; (2) increased thickness causes heat-treatment issues related to nonuniformity across the thickness and thus not achieving the optimum properties; (3) fracture toughness (ductile-to-brittle transition ) is a critical safety issue for these vessels, and it is affected in thick sections due to nonuniformity of microstructure; (4) PWHT needed after welding and makes fabrication more time-consuming with increased cost; and (5) PWHT needed after welding also limits any modifications of the large vessels in service. The goal of this project was to reduce the weight of large-pressure vessel components (ranging from 100 to 300 tons) by approximately 25% and reduce fabrication cost and improve in-service modification feasibility through development of Fe-3Cr-W(V) steels with combination of nearly a 50% higher strength, a lower DBTT and a higher upper-shelf energy

  2. The effects of silicon and titanium on void swelling and phase transformations in neutron irradiated 12Cr-15Ni steels

    NASA Astrophysics Data System (ADS)

    Boothby, R. M.; Williams, T. M.

    1988-05-01

    12Cr-15Ni-0.25Ti steels with Si additions of 0.5, 0.9 and 1.4 wt% have been irradiated to a maximum dose of 47 dpa at temperatures ranging from 399 to 649°C. Detailed microstructural examinations of void swelling, precipitation behaviour and austenite instability have been made. Assessments of swelling and matrix phase transformations have also been made using density and induced magnetization measurements respectively. Austenite instability was increased by Si additions; the transformation product was usually ferrite although some martensite was also observed, and compositional fluctuations in untransformed austenite were detected. Precipitation, particularly of G phase, became more extensive and swelling in solution-treated alloys was reduced at higher Si contents. Enhanced growth of voids attached to G phase precipitates was observed. Cold-working decreased both swelling and ferrite formation. A fine dispersion of TiC was effective in suppressing swelling at high irradiation temperature as long as the precipitates remained stable. The stability of TiC was increased by cold-working but reduced by Si additions.

  3. Low activation ferritic alloys

    DOEpatents

    Gelles, David S.; Ghoniem, Nasr M.; Powell, Roger W.

    1986-01-01

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  4. Low activation ferritic alloys

    DOEpatents

    Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

    1985-02-07

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  5. The development of ferritic-martensitic steels with reduced long-term activation

    NASA Astrophysics Data System (ADS)

    Ehrlich, K.; Kelzenberg, S.; Röhrig, H.-D.; Schäfer, L.; Schirra, M.

    1994-09-01

    Ferritic-martensitic 9-12% CrMoVNb steels of MANET type possess a number of advantageous properties for fusion reactor application. Their optimization has led to improved creep and fracture-toughness properties. New 9-10% CrWVTa alloys have been developed by KfK/IMF in collaboration with the SAARSTAHL GmbH which have a reduced long-term activation and show in addition superior fracture toughness properties. The calculation of dose rate and other radiological parameters with the presently available FISPACT/EAF codes, extended by KfK files for sequential reactions has shown that the long-term dose-rate in these alloys is governed by the remaining 'impurity level' of Nb and the alloying elements W and Ta. Sequential reactions — though relevant for single alloying elements like Cr, Mn, V and N — provide only a second order effect in Fe-based alloys. A challenge for the future materials development is the production of alloys with the desired narrow specification of elements and impurities, which necessitates new ways of steelmaking.

  6. The impact of different flooding periods on the dynamics of pore water concentrations of As, Cr, Mo and V in a contaminated floodplain soil - results of a lysimeter study

    NASA Astrophysics Data System (ADS)

    Rupp, Holger; Meissner, Ralph; Shaheen, Sabry; Rinklebe, Jörg

    2014-05-01

    Trace elements and arsenic (As) were transported with water during inundation in floodplain ecosystems, where they settled down and accumulated predominantly in depressions and low-lying terraces. Highly variable hydrological conditions in floodplains can affect the dynamics of pollutants. The impact of different flooding/drying periods on the temporal dynamics of pore water concentrations of As, Cr, Mo and V as a function of soil EH/pH changes and dynamics of DOC, Fe, Mn and SO42- was studied in a contaminated floodplain soil collected at the Elbe River (Germany). A specific groundwater lysimeter technique with two separate small lysimeter vessels served as replicates was used for this study. The groundwater level inside the lysimeters was controlled to simulate long term and short term flooding/drying. The long term (LT) flooding scenario consists of 94 days of flooding followed by similar drying term. The short term (ST) flooding/drying scenario comprises 21 days and was six times repeated. The entire experimental period (LT_ST) was about 450 days. Flooding of the soil caused a significant decrease of EH and pH. Concentrations of soluble As, Cr, Fe, Mn, Mo and DOC were higher under reducing conditions than under oxidizing conditions in LT. However, As and Cr tended to be mobilized under oxidizing conditions during ST, which might be due to slow kinetics of the redox reaction of As and Cr. Dynamics of Mo were more affected by changes of EH/pH as compared to As, Cr and V and governed mainly by Fe-Mn chemistry. Concentrations of V in ST were higher than in LT and were controlled particularly by pH and chemistry of Fe. The interactions between the elements and carriers studied were stronger during long flood-dry-cycles than during short cycles, which confirmed our hypothesis. We conclude that the dynamics of As, Cr, Mo and V are determined by the length of time soils are exposed to flooding, because drivers of element mobility need a certain time to provoke

  7. Characterisation of Cr, Si and P distribution at dislocations and grain-boundaries in neutron irradiated Fe-Cr model alloys of low purity

    NASA Astrophysics Data System (ADS)

    Kuksenko, V.; Pareige, C.; Genevois, C.; Pareige, P.

    2013-03-01

    Segregations at some dislocations and grain boundaries in Fe-5%Cr, Fe-9%Cr and Fe-12%Cr model alloys of low purity after neutron irradiation at 300 °C up to 0.6 dpa have been analyzed with atom probe tomography. All dislocation lines and low- and high-angle grain boundaries (GBs) which have been observed were enriched with Cr, Si and P. The segregations reveal the different dislocation structures associated to different type of analysed GBs. Cr and Si atoms were found to be nonhomogenously distributed around the dislocation cores because of the non isotropic stress field induced by edge dislocation lines. Concerning GBs, precipitate free zones (PFZs) are exhibited around the planar defects which were analysed in Fe-9%Cr and Fe-12%Cr model alloys. These PFZ are size dependant with the nominal level of Cr.

  8. Specification of CuCrZr Alloy Properties after Various Thermo-Mechanical Treatments and Design Allowables including Neutron Irradiation Effects

    SciTech Connect

    Barabash, Vladimir; Kalinin, G. M.; Fabritsiev, Sergei A.; Zinkle, Steven J

    2012-01-01

    Precipitation hardened CuCrZr alloy is a promising heat sink and functional material for various applica- tions in ITER, for example the first wall, blanket electrical attachment, divertor, and heating systems. Three types of thermo-mechanical treatment were identified as most promising for the various applica- tions in ITER: solution annealing, cold working and ageing; solution annealing and ageing; solution annealing and ageing at non-optimal condition due to specific manufacturing processes for engineer- ing-scale components. The available data for these three types of treatments were assessed and mini- mum tensile properties were determined based on recommendation of Structural Design Criteria for the ITER In-vessel Components. The available data for these heat treatments were analyzed for assess- ment of neutron irradiation effect. Using the definitions of the ITER Structural Design Criteria the design allowable stress intensity values are proposed for CuCrZr alloy after various heat treatments.

  9. Effect of neutron irradiation on the London penetration depth for polycrystalline Bi(1.8)Pb(0.3)Sr2Ca2Cu3O10 superconductor

    NASA Technical Reports Server (NTRS)

    Ossandon, J. G.; Thompson, J. R.; Sun, Yang Ren; Christen, D. K.; Chakoumakos, B. C.

    1995-01-01

    Magnetization studies of polycrystalline Bi(1.8)Pb(0.3)Sr2Ca2Cu3O10 superconductor, prior to and after neutron irradiation, showed an increase in J(sub c) due to irradiation damage. Analysis of the equilibrium magnetization revealed significant increases in other more fundamental properties. In particular, the London penetration depth increased by approximately 15 percent following irradiation with 8 x 10(exp 16) neutrons/sq cm. Corresponding changes were observed in the upper critical magnetic field H(sub c2). However, the most fundamental thermodynamic property, the superconductive condensation energy F(sub c), was unaffected by the moderate level of neutron-induced damage.

  10. Dependence of the rate of steady-state swelling of fuel-element claddings made of ChS68 steel on the characteristics of neutron irradiation

    NASA Astrophysics Data System (ADS)

    Kozlov, A. V.; Portnykh, I. A.

    2016-08-01

    Rate of steady-state swelling of fuel-element sheaths made of the 06Kh16N15M2G2TFR steel in the course of their operation in a BN-600 reactor has been calculated. In the calculations, the diffusion characteristics of point defects and the results of the determination of the characteristics of the irradiation-induced porosity have been used. The dependence of the dose rate of steady-state swelling on neutron-irradiation characteristics has been analyzed. It has been established that the dose rate of swelling at the steady-state stage is independent of the energy of migration of vacancies and the rate of generation of atomic displacements.

  11. Alloy Design and Development of Cast Cr-W-V Ferritic Steels for Improved High-Temperature Strength for Power Generation Applications

    SciTech Connect

    Klueh, R L; Maziasz, P J; Vitek, J M; Evans, N D; Hashimoto, N

    2006-09-23

    Economic and environmental concerns demand that the power-generation industry seek increased efficiency for gas turbines. Higher efficiency requires higher operating temperatures, with the objective temperature for the hottest sections of new systems {approx} 593 C, and increasing to {approx} 650 C. Because of their good thermal properties, Cr-Mo-V cast ferritic steels are currently used for components such as rotors, casings, pipes, etc., but new steels are required for the new operating conditions. The Oak Ridge National Laboratory (ORNL) has developed new wrought Cr-W-V steels with 3-9% Cr, 2-3% W, 0.25% V (compositions are in wt.%), and minor amounts of additional elements. These steels have the strength and toughness required for turbine applications. Since cast alloys are expected to behave differently from wrought material, work was pursued to develop new cast steels based on the ORNL wrought compositions. Nine casting test blocks with 3, 9, and 11% Cr were obtained. Eight were Cr-W-V-Ta-type steels based on the ORNL wrought steels; the ninth was COST CB2, a 9Cr-Mo-Co-V-Nb cast steel, which was the most promising cast steel developed in a European alloy-development program. The COST CB2 was used as a control to which the new compositions were compared, and this also provided a comparison between Cr-W-V-Ta and Cr-Mo-V-Nb compositions. Heat treatment studies were carried out on the nine castings to determine normalizing-and-tempering treatments. Microstructures were characterized by both optical and transmission electron microscopy (TEM). Tensile, impact, and creep tests were conducted. Test results on the first nine cast steel compositions indicated that properties of the 9Cr-Mo-Co-V-Nb composition of COST CB2 were better than those of the 3Cr-, 9Cr-, and 11Cr-W-V-Ta steels. Analysis of the results of this first iteration using computational thermodynamics raised the question of the effectiveness in cast steels of the Cr-W-V-Ta combination versus the Cr-Mo

  12. Elaboration, étude structurale et analyse CHARDI et BVS d'une nouvelle variété β-Na9Cr(MoO4)6 de type alluaudite.

    PubMed

    Sonni, Manel; Marzouki, Riadh; Zid, Mohamed Faouzi; Souilem, Amira

    2016-06-01

    The title compound, nonasodium chromium(III) hexakis[molybdate(VI)], β-Na9CrMo6O24, was prepared by solid-state reactions. This alluaudite-type structure is constituted of infinite layers formed by links between M 2O10 (M = C/Na) dimers and MoO4 tetra-hedra. The Na(+) and Cr(3+) cations are located in the same site with, respectively, 0.25 and 0.75 occupancies. The layers are connected to each other through MoO4 sharing corners, resulting an in open three-dimensional framework with hexa-gonal-form cavities occupied by Na(+) cations. The proposed structural model is supported by charge-distribution (CHARDI) and bond-valence-sum (BVS) analysis. All atoms are on general positions except for one Mo, two Na (site symmetry 2) and another Na site (site symmetry -1). A comparison is made with the similar structures Na4Co(MoO4)3, Na2Ni(MoO4)2, Cu1.35Fe3(PO4)3 and NaAgFeMn2(PO4)3. PMID:27308053

  13. Magnetic and electrical properties of flux grown single crystals of Ln{sub 6}M{sub 4}Al{sub 43} (Ln=Gd, Yb; M=Cr, Mo, W)

    SciTech Connect

    Kangas, Michael J.; Treadwell, LaRico J.; Haldolaarachchige, Neel; McAlpin, Jacob D.; Young, David P.; Chan, Julia Y.

    2013-01-15

    Millimeter-sized single crystals of Ln{sub 6}M{sub 4}Al{sub 43} (Ln=Gd, Yb; M=Cr, Mo, W) were successfully grown with a molten aluminum flux. Synthetic conditions and physical properties for single crystals of all six analogs are discussed. The compounds exhibit metallic resistivity with room temperature values between 0.1 and 0.6 m{Omega}-cm. The Yb analogs are Pauli paramagnets with the Yb ion adopting the nonmagnetic divalent configuration (Yb{sup 2+}). Gd{sub 6}Cr{sub 4}Al{sub 43}, Gd{sub 6}Mo{sub 4}Al{sub 43}, and Gd{sub 6}W{sub 4}Al{sub 43} appear to order antiferromagnetically at 19, 15, and 15 K, respectively. - Graphical abstract: The crystal structure of Yb{sub 6}Cr{sub 4}Al{sub 43}. The light and dark green polyhedra show the chromium sublattice. Highlights: Black-Right-Pointing-Pointer Single crystals up to 0.5 cm in length were grown with a molten aluminum flux. Black-Right-Pointing-Pointer Physical property measurements were conducted on single crystals. Black-Right-Pointing-Pointer Gadolinium analogs appear to order antiferromagnetically with positive {theta}. Black-Right-Pointing-Pointer All analogs show metallic resistivity.

  14. Elaboration, étude structurale et analyse CHARDI et BVS d’une nouvelle variété β-Na9Cr(MoO4)6 de type alluaudite

    PubMed Central

    Sonni, Manel; Marzouki, Riadh; Zid, Mohamed Faouzi; Souilem, Amira

    2016-01-01

    The title compound, nonasodium chromium(III) hexakis[molybdate(VI)], β-Na9CrMo6O24, was prepared by solid-state reactions. This alluaudite-type structure is constituted of infinite layers formed by links between M 2O10 (M = C/Na) dimers and MoO4 tetra­hedra. The Na+ and Cr3+ cations are located in the same site with, respectively, 0.25 and 0.75 occupancies. The layers are connected to each other through MoO4 sharing corners, resulting an in open three-dimensional framework with hexa­gonal-form cavities occupied by Na+ cations. The proposed structural model is supported by charge-distribution (CHARDI) and bond-valence-sum (BVS) analysis. All atoms are on general positions except for one Mo, two Na (site symmetry 2) and another Na site (site symmetry -1). A comparison is made with the similar structures Na4Co(MoO4)3, Na2Ni(MoO4)2, Cu1.35Fe3(PO4)3 and NaAgFeMn2(PO4)3. PMID:27308053

  15. Effect of scanning speeds on microstructure and wear behavior of laser-processed NiCr-Cr3C2-MoS2-CeO2 on 38CrMoAl steel

    NASA Astrophysics Data System (ADS)

    Sun, Guifang; Tong, Zhaopeng; Fang, Xiaoyu; Liu, Xiaojun; Ni, Zhonghua; Zhang, Wei

    2016-03-01

    Self-lubricating wear-resistant NiCr-Cr3C2-MoS2-CeO2 layers were fabricated on 38CrMoAl extruder screws by laser processing. The effect of scanning speeds on microstructure, phases, microhardness, and wear behavior was investigated. The obtained results indicate that the laser-processed layers had fine and nonuniform microstructures with undissolved MoS2 particles distributed on the matrix. With an increase of the laser-scanning speeds, the microstructures changed from hypoeutectic to hypereutectic, volume fraction of martensite increased, microhardness increased, and thickness and friction coefficients of the layers decreased. Wear resistance of the optimized layer was increased by 29.76 times compared with that of the substrate. The undissolved MoS2 was separated from the matrix on loading. In addition to the grain-refining and solution-strengthening effects, oxide films formed on the surface of the layers shielded them and enhanced their wear resistance. The crack or fracture behavior of the laser-processed layers on loading was determined by its toughness, which also had an important effect on the wear behavior of the processed layers.

  16. High strength ferritic alloy

    DOEpatents

    Hagel, William C.; Smidt, Frederick A.; Korenko, Michael K.

    1977-01-01

    A high-strength ferritic alloy useful for fast reactor duct and cladding applications where an iron base contains from about 9% to about 13% by weight chromium, from about 4% to about 8% by weight molybdenum, from about 0.2% to about 0.8% by weight niobium, from about 0.1% to about 0.3% by weight vanadium, from about 0.2% to about 0.8% by weight silicon, from about 0.2% to about 0.8% by weight manganese, a maximum of about 0.05% by weight nitrogen, a maximum of about 0.02% by weight sulfur, a maximum of about 0.02% by weight phosphorous, and from about 0.04% to about 0.12% by weight carbon.

  17. Study of the structure and properties of metal of the major steam lines of a CCGT-420 unit made from high-chromium X10CrMoVNb9-1 (P91) steel

    NASA Astrophysics Data System (ADS)

    Grin', E. A.; Anokhov, A. E.; Pchelintsev, A. V.; Krüger, E.-T.

    2016-07-01

    The technology of manufacture of live steam lines and hot reheat lines at FINOW Rohrsysteme GmbH are discussed. These pipelines are designed for high-performance CCGT units and are made from high-chromium martensitic steel X10CrMoVNb9-1 (P91). The principles of certification and evaluation of conformance of thermal and mechanical equipment made from new construction materials with the TRCU 032-2013 technical regulation of the Customs Union are detailed. The requirements outlined in Russian and international regulatory documents regarding the manufacture of pipes and semifinished products for pipeline systems are compared. The characteristic features of high-chromium martensitic steel, which define the requirements for its heat treatment and welding, are outlined. The methodology and the results of a comprehensive analysis of metal of pipes, fittings, and weld joints of steam lines are presented. It is demonstrated that the short-term mechanical properties of metal (P91 steel) of pipes, bends, and weld joints meet the requirements of European standards and Russian technical specifications. The experimental data on long-term strength of metal of pipes from a live steam line virtually match the corresponding reference curve from the European standard, while certain experimental points for metal of bends of this steam line and metal of pipes and bends from a hot reheat line lie below the reference curve, but they definitely stay within the qualifying (20%) interval of the scatter band. The presence of a weakened layer in the heat-affected zone of weld joints of steel P91 is established. It is shown that the properties of this zone govern the short-term and long-term strength of weld joints in general. The results of synthesis and analysis of research data support the notion that the certification testing of steam lines and other equipment made from chromium steels should necessarily involve the determination of long-term strength parameters.

  18. Recovery behavior of high purity cubic SiC polycrystals by post-irradiation annealing up to 1673 K after low temperature neutron irradiation

    NASA Astrophysics Data System (ADS)

    Idris, Mohd Idzat; Yamazaki, Saishun; Yoshida, Katsumi; Yano, Toyohiko

    2015-10-01

    Two kinds of high purity cubic (β) SiC polycrystals, PureBeta-SiC and CVD-SiC, were irradiated in the BR2 reactor (Belgium) up to a fluence of 2.0-2.5 × 1024 (E > 0.1 MeV) at 333-363 K. Changes in macroscopic lengths were examined by post-irradiation thermal annealing using a precision dilatometer up to 1673 K with a step-heating method. The specimen was held at each temperature step for 6 h and the change in length of the specimen was recorded during each isothermal annealing step from 373 K to 1673 K with 50 K increments. The recovery curves were analyzed with the first order model, and rate constants at each annealing step were obtained. Recovery of defects, induced by neutron irradiation in high purity β-SiC, has four stages of different activation energies. At 373-573 K, the activation energy of PureBeta-SiC and CVD-SiC was in the range of 0.17-0.24 eV and 0.12-0.14 eV; 0.002-0.04 eV and 0.006-0.04 eV at 723-923 K; 0.20-0.27 eV and 0.26-0.31 eV at 923-1223 K; and 1.37-1.38 eV and 1.26-1.29 eV at 1323-1523 K, respectively. Below ∼1223 K the recombination occurred possibly for closely positioned C and Si Frenkel pairs, and no long range migration is deemed essential. Nearly three-fourths of recovery, induced by neutron irradiation, occur by this mechanism. In addition, at 1323-1523 K, recombination of slightly separated C Frenkel pairs and more long-range migration of Si interstitials may have occurred for PureBeta-SiC and CVD-SiC specimens. Migration of both vacancies may be restricted up to ∼1523 K. Comparing to hexagonal α-SiC, high purity β-SiC recovered more quickly in the lower annealing temperature range of less than 873 K, in particular less than 573 K.

  19. Mechanical Performance of Ferritic Martensitic Steels for High Dose Applications in Advanced Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    Anderoglu, Osman; Byun, Thak Sang; Toloczko, Mychailo; Maloy, Stuart A.

    2013-01-01

    Ferritic/martensitic (F/M) steels are considered for core applications and pressure vessels in Generation IV reactors as well as first walls and blankets for fusion reactors. There are significant scientific data on testing and industrial experience in making this class of alloys worldwide. This experience makes F/M steels an attractive candidate. In this article, tensile behavior, fracture toughness and impact property, and creep behavior of the F/M steels under neutron irradiations to high doses with a focus on high Cr content (8 to 12) are reviewed. Tensile properties are very sensitive to irradiation temperature. Increase in yield and tensile strength (hardening) is accompanied with a loss of ductility and starts at very low doses under irradiation. The degradation of mechanical properties is most pronounced at <0.3 T M ( T M is melting temperature) and up to 10 dpa (displacement per atom). Ferritic/martensitic steels exhibit a high fracture toughness after irradiation at all temperatures even below 673 K (400 °C), except when tested at room temperature after irradiations below 673 K (400 °C), which shows a significant reduction in fracture toughness. Creep studies showed that for the range of expected stresses in a reactor environment, the stress exponent is expected to be approximately one and the steady state creep rate in the absence of swelling is usually better than austenitic stainless steels both in terms of the creep rate and the temperature sensitivity of creep. In short, F/M steels show excellent promise for high dose applications in nuclear reactors.

  20. Influence of LBE long term exposure and simultaneous fast neutron irradiation on the mechanical properties of T91 and 316L

    NASA Astrophysics Data System (ADS)

    Stergar, E.; Eremin, S. G.; Gavrilov, S.; Lambrecht, M.; Makarov, O.; Iakovlev, V.

    2016-05-01

    The LEXUR-II-LBE irradiation campaign was conducted from 2011 to 2012 and was aimed to investigate the combined influence of irradiation and LBE environment. In this irradiation campaign tensile test samples, pressurized tubes and corrosion samples were irradiated in LBE filled capsules. To separate the effect of exposure to LBE and neutron irradiation a parallel furnace experiment where the samples were exposed to LBE at the irradiation temperature for the corresponding time was conducted. Here we report results of the first extracted capsule which was irradiated about 6 months and dismantled after a cooling phase to decrease activity. The results of SSRT tests for irradiated T91 show that the exposure to LBE at 350 °C for a long time leads to the appearance of liquid metal embrittlement without any pre-treatment which is usually necessary to promote LME. Irradiation increases the effect of LME on the ductility of T91. In contrast to the findings for T91 the gained results also show that tensile tests on irradiated austenitic stainless steel 316L show no influence of LBE environment on the tensile properties.

  1. Recent results on the neutron irradiation of ITER candidate copper alloys irradiated in DR-3 at 250{degrees}C to 0.3 dpa

    SciTech Connect

    Edwards, D.J.; Singh, B.N.; Toft, P.; Eldrup, M.

    1997-04-01

    Tensile specimens of CuCrZr and CuNiBe alloys were given various heat treatments corresponding to solution anneal, prime-ageing and bonding thermal treatment with additional specimens re-aged and given a reactor bakeout treatment at 350{degrees}C for 100 h. CuAl-25 was also heat treated to simulate the effects of a bonding thermal cycle on the material. A number of heat treated specimens were neutron irradiated at 250{degrees}C to a dose level of {approximately}0.3 dpa in the DR-3 reactor as Riso. The main effect of the bonding thermal cycle heat treatment was a slight decrease in strength of CuCrZr and CuNiBe alloys. The strength of CuAl-25, on the other hand, remained almost unaltered. The post irradiation tests at 250{degrees}C showed a severe loss of ductility in the case of the CuNiBe alloy. The irradiated CuAl-25 and CuCrZr specimens exhibited a reasonable amount of uniform elongation, with CuCrZr possessing a lower strength.

  2. Low-temperature low-dose neutron irradiation effects on Brush Wellman S65-C and Kawechi Berylco P0 beryllium

    SciTech Connect

    Snead, L.L.

    1998-09-01

    The mechanical property results for two high quality beryllium materials subjected to low temperature, low dose neutron irradiation in water moderated reactors are presented. Materials chosen were the S65-C ITER candidate material produced by Brush Wellman, and Kawecki Berylco Industries P0 beryllium. Both materials were processed by vacuum hot pressing. Mini sheet tensile and thermal diffusivity specimens were irradiated in the temperature range of {approximately}100--275 C from a fast (E > 0.1 MeV) neutron dose of 0.05 to 1.0 {times} 10{sup 25} n/m{sup 2} in the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory and the High Flux Beam Reactor (HFBR) at the Brookhaven National Laboratory. As expected from earlier work on beryllium, both materials underwent significant embrittlement with corresponding reduction in ductility and increased strength. Both thermal diffusivity and volumetric expansion were measured and found to be negligible in this temperature and fluence range. Of significance from this work is that while both materials rapidly embrittle at these ITER relevant irradiation conditions, some ductility (>1--2%) remains, which contrasts with a body of earlier work including recent work on the Brush-Wellman S65-C material irradiated to slightly higher neutron fluence.

  3. The influence of fast neutron irradiation on the intra- and intergrain properties of the polycrystalline BiPbSrCaCuO system

    NASA Astrophysics Data System (ADS)

    Wiśniewski, A.; Baran, M.; Kozioł, Z.; Przysłupski, P.; Piechota, J.; Puźniak, R.; Pajaçzkowska, A.; Pȩkała, M.; Pytel, B.; Pytel, K.

    1990-09-01

    The influence of irradiation by fast neutrons with fluences from 3.3 x 10 16n/ cm2 up to 3 x 10 18n/ cm2 on the physical properties of polycrystalline Bi0.7Pb0.3SrCaCu1.8Ox was examined. Studies of DC magnetization, AC susceptibility, transport and thermoelectric power were performed. The irradiation caused a decrease of Tc, determined from the onset of diamagnetism, by as much as 31 K for a fluence of 3 x 10 18n/ cm2. A strong influence of neutron irradiation on both intra- and intergranular properties was observed. The defects within the superconducting grains created by neutrons caused an increase of the pinning forces which enhanced the critical magnetization current. A gradual decoupling of Josephson weak links with increasing neutron fluence was observed in transport and low field magnetization measurements. From the AC susceptibility measurements the irreversibility lines between the flux-creep and flux-flow regions were determined. An increase of the absolute values of thermoelectric power with rising fluence was noticed.

  4. A study of the neutron irradiation effects on the susceptibility to embrittlement of A316L and T91 steels in lead bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Sapundjiev, D.; Al Mazouzi, A.; Van Dyck, S.

    2006-09-01

    The effects of neutron irradiation on the susceptibility to liquid metal embrittlement of two primary selected materials for MYRRHA project an accelerator driven system (ADS), was investigated by means of slow strain rate tests (SSRT). The latter were carried out at 200 °C in nitrogen and in liquid Pb-Bi at a strain rate of 5 × 10 -6 s -1. The small tensile specimens were irradiated at the BR-2 reactor in the MISTRAL irradiation rig at 200 °C for 3 reactor cycles to reach a dose of about 1.50 dpa. The SSR tests were carried out under poor and under dissolved oxygen conditions (˜1.5 × 10 -12 wt% dissolved oxygen) which at this temperature will favour formation of iron and chromium oxides. Although both materials differ in structure (fcc for A316L against bcc for T91), their flow behaviour in contact with liquid lead bismuth eutectic before and after irradiation is very similar. Under these testing conditions none of them was found susceptible to liquid metal embrittlement (LME).

  5. Investigation of the thermo-mechanical behavior of neutron-irradiated Fe-Cr alloys by self-consistent plasticity theory

    NASA Astrophysics Data System (ADS)

    Xiao, Xiazi; Terentyev, Dmitry; Yu, Long; Bakaev, A.; Jin, Zhaohui; Duan, Huiling

    2016-08-01

    The thermo-mechanical behavior of non-irradiated (at 223 K, 302 K and 573 K) and neutron irradiated (at 573 K) Fe-2.5Cr, Fe-5Cr and Fe-9Cr alloys is studied by a self-consistent plasticity theory, which consists of constitutive equations describing the contribution of radiation defects at grain level, and the elastic-viscoplastic self-consistent method to obtain polycrystalline behaviors. Attention is paid to two types of radiation-induced defects: interstitial dislocation loops and solute rich clusters, which are believed to be the main sources of hardening in Fe-Cr alloys at medium irradiation doses. Both the hardening mechanism and microstructural evolution are investigated by using available experimental data on microstructures, and implementing hardening rules derived from atomistic data. Good agreement with experimental data is achieved for both the yield stress and strain hardening of non-irradiated and irradiated Fe-Cr alloys by treating dislocation loops as strong thermally activated obstacles and solute rich clusters as weak shearable ones.

  6. New Ferritic Steels with Combined Optimal Creep Resistance and Ductility by Coupling Thermodynamic Calculations with Focused Experiments

    SciTech Connect

    Teng, Zhenke; Zhang, F; Miller, Michael K; Liu, Chain T; Huang, Shenyan; Chou, Y; Tien, R; Chang, Y A; Liaw, Peter K

    2012-01-01

    Two critical issues restricting the applications of NiAl precipitate-strengthened ferritic steels are their poor room temperature ductility and insufficient creep resistance at temperatures higher than 600 C. In this study, a thermodynamic modeling approach is integrated with experiments focused on investigating the ductility and creep resistance of steel alloys based on the Fe-Ni-Al-Cr-Mo multi-component system. The mechanical property studies showed that the creep resistance increases with increasing the volume fraction of B2-ordered precipitates, while the opposite trend was observed for the ductility. Low solubility of Al in the {alpha}-Fe matrix was found to favor a ductility increase. Thermodynamic calculations were used to predict the volume fraction of B2-ordered precipitate and the elemental partitioning to guide the selection of alloy compositions that might exhibit the balanced creep resistance and ductility. Key experiments were then conducted to validate the prediction. This integrated approach was found to be very effective in the alloy development.

  7. Processing and application of nanosized ferrite powders

    SciTech Connect

    Drofenik, M.; Rozman, M.

    1995-09-01

    Crystalline MnZn ferrite of nanosize was prepared by the hydrothermal synthesis. The pH value of the starting suspension was found to influence substantially the ferrite composition. The nanosized ferrite powder is very sensitive to oxidation and sinters to nearly theoretical density in nitrogen. The correlation between the eddy-current loss and microstructure is given.

  8. High power ferrite microwave switch

    NASA Technical Reports Server (NTRS)

    Bardash, I.; Roschak, N. K.

    1975-01-01

    A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

  9. Articles comprising ferritic stainless steels

    DOEpatents

    Rakowski, James M.

    2016-06-28

    An article of manufacture comprises a ferritic stainless steel that includes a near-surface region depleted of silicon relative to a remainder of the ferritic stainless steel. The article has a reduced tendency to form an electrically resistive silica layer including silicon derived from the steel when the article is subjected to high temperature oxidizing conditions. The ferritic stainless steel is selected from the group comprising AISI Type 430 stainless steel, AISI Type 439 stainless steel, AISI Type 441 stainless steel, AISI Type 444 stainless steel, and E-BRITE.RTM. alloy, also known as UNS 44627 stainless steel. In certain embodiments, the article of manufacture is a fuel cell interconnect for a solid oxide fuel cell.

  10. Using solution- and solid-state S K-edge X-ray absorption spectroscopy with density functional theory to evaluate M-S bonding for MS4(2-) (M = Cr, Mo, W) dianions.

    PubMed

    Olson, Angela C; Keith, Jason M; Batista, Enrique R; Boland, Kevin S; Daly, Scott R; Kozimor, Stosh A; MacInnes, Molly M; Martin, Richard L; Scott, Brian L

    2014-12-14

    Herein, we have evaluated relative changes in M-S electronic structure and orbital mixing in Group 6 MS4(2-) dianions using solid- and solution-phase S K-edge X-ray absorption spectroscopy (XAS; M = Mo, W), as well as density functional theory (DFT; M = Cr, Mo, W) and time-dependent density functional theory (TDDFT) calculations. To facilitate comparison with solution measurements (conducted in acetonitrile), theoretical models included gas-phase calculations as well as those that incorporated an acetonitrile dielectric, the latter of which provided better agreement with experiment. Two pre-edge features arising from S 1s → e* and t electron excitations were observed in the S K-edge XAS spectra and were reasonably assigned as (1)A1 → (1)T2 transitions. For MoS4(2-), both solution-phase pre-edge peak intensities were consistent with results from the solid-state spectra. For WS4(2-), solution- and solid-state pre-edge peak intensities for transitions involving e* were equivalent, while transitions involving the t orbitals were less intense in solution. Experimental and computational results have been presented in comparison to recent analyses of MO4(2-) dianions, which allowed M-S and M-O orbital mixing to be evaluated as the principle quantum number (n) for the metal valence d orbitals increased (3d, 4d, 5d). Overall, the M-E (E = O, S) analyses revealed distinct trends in orbital mixing. For example, as the Group 6 triad was descended, e* (π*) orbital mixing remained constant in the M-S bonds, but increased appreciably for M-O interactions. For the t orbitals (σ* + π*), mixing decreased slightly for M-S bonding and increased only slightly for the M-O interactions. These results suggested that the metal and ligand valence orbital energies and radial extensions delicately influenced the orbital compositions for isoelectronic ME4(2-) (E = O, S) dianions.

  11. Using Solution- and Solid-State S K-edge X-ray Absorption Spectroscopy with Density Functional Theory to Evaluate M–S Bonding for MS42- (M = Cr, Mo, W) Dianions

    PubMed Central

    Olson, Angela C.; Keith, Jason M.; Batista, Enrique R.; Boland, Kevin S.; Daly, Scott R.; Kozimor, Stosh A.; MacInnes, Molly M.; Martin, Richard L.; Scott, Brian L.

    2014-01-01

    Herein, we have evaluated relative changes in M–S electronic structure and orbital mixing in Group 6 MS42- dianions using solid- and solution-phase S K-edge X-ray absorption spectroscopy (XAS; M = Mo, W), as well as density functional theory (DFT; M = Cr, Mo, W) and time-dependent density functional theory (TDDFT) calculations. To facilitate comparison with solution measurements (conducted in acetonitrile), theoretical models included gas-phase calculations as well as those that incorporated an acetonitrile dielectric, the latter of which provided better agreement with experiment. Two pre-edge features arising from S 1s → e* and t2* electron excitations were observed in the S K-edge XAS spectra and were reasonably assigned as 1A1 → 1T2 transitions. For MoS42-, both solution-phase pre-edge peak intensities were consistent with results from the solid-state spectra. For WS42-, solution- and solid-state pre-edge peak intensities for transitions involving e* were equivalent, while transitions involving the t2* orbitals were less intense in solution. Experimental and computational results have been presented in comparison to recent analyses of MO42- dianions, which allowed M–S and M–O orbital mixing to be evaluated as the principle quantum number (n) for the metal valence d orbitals increased (3d, 4d, 5d). Overall, the M–E (E = O, S) analyses revealed distinct trends in orbital mixing. For example, as the Group 6 triad was descended, e* (π*) orbital mixing remained constant in the M–S bonds, but increased appreciably for M–O interactions. For the t2* orbitals (σ* + π*), mixing decreased slightly for M–S bonding and increased only slightly for the M–O interactions. These results suggested that the metal and ligand valence orbital energies and radial extensions delicately influenced the orbital compositions for isoelectronic ME42- (E = O, S) dianions. PMID:25311904

  12. RF cavities with transversely biased ferrite tuning

    SciTech Connect

    Smythe, W.R.; Brophy, T.G.; Carlini, R.D.; Friedrichs, C.C.; Grisham, D.L.; Spalek, G.; Wilkerson, L.C.

    1985-10-01

    Earley et al. suggested that ferrite tuned rf cavities have lower ferrite power dissipation if the ferrite bias field is perpendicular rather than parallel to the rf magnetic field. A 50-84 MHz cavity has been constructed in which ferrite can be biased either way. Low power measurements of six microwave ferrites show that the magnetic Q's of these ferrites under perpendicular bias are much higher than under parallel bias, and that the high Q region extends over a much wider range of rf permeability. TDK Y-5 ferrite was found to have a magnetic Q of 10,800, 4,800, 1,200 and 129 at rf permeabilities of 1.2, 2.4, 3.7 and 4.5, respectively. Measurements of perpendicularly biased ferrite at various power levels were made in a coaxial line cavity. The Q of Y-5 ferrite was found to decrease by less than a factor of 2 as the power density in the ferrite was increased to 1.3 W/cmT. A cavity design for a 6 GeV, high current, rapid cycling synchrotron using transversely biased ferrite tuning is described.

  13. Safe Use Limits for Advanced Ferritic Steels in Ultra-Supercritical Power Boilers.

    SciTech Connect

    Swindeman, RW

    2003-11-03

    In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Babcock & Wilcox Company to examine the databases for advanced ferritic steels and determine the safe limits for operation in supercritical steam power boilers. The materials of interest included the vanadium-modified 9-12% Cr steels with 1-2% Mo or W. The first task involved a review of pertinent information and the down-selection of a steel of special interest. The long-time database for 9Cr-1Mo-V steel was found to be most satisfactory for the examinations, and this steel was taken to be representative of the group. The second task involved the collection of aged and service exposed samples for metallurgical and mechanical testing. Here, aged samples to 75,000 hours, laboratory-tested samples to 83,000 hours, and service-exposed sample with up to 143,000 hours exposure were collected. The third task involved mechanical testing of exposed samples. Creep-rupture testing to long times was undertaken. Variable stress and temperature testing was included. Results were compared against the prediction of damage models. These models seemed to be adequate for life prediction. The fourth task involved the metallurgical examination of exposed specimens. Changes in microstructure were compared against published information on the evolution of microstructures in 9Cr-Mo-V steels and the results were found to be consistent with expectations. The fifth task involved a survey of steam and fireside corrosion. Data from the service-exposed tubing was examined, and a literature survey was undertaken as part of an activity in support of ultra-supercritical steam boiler technology. The corrosion study indicated some concerns about long-time fireside corrosion and suggested temperature limits were needed for corrosive coal ash conditions.

  14. Study of Li 2TiO 3 + 5 mol% TiO 2 lithium ceramics after long-term neutron irradiation

    NASA Astrophysics Data System (ADS)

    Chikhray, Y.; Shestakov, V.; Maksimkin, O.; Turubarova, L.; Osipov, I.; Kulsartov, T.; Kuykabayeba, A.; Tazhibayeva, I.; Kawamura, H.; Tsuchiya, K.

    2009-04-01

    Given work presents the results of complex material-science studies of 1 mm diameter ceramic pebbles manufactured of Li 2TiO 3 + 5 mol% TiO 2 ceramics before and after long-time neutron irradiation. Ceramic samples were placed in specially ampoules (six items) made of stainless steel Cr18Ni10Ti which were vacuumized and filled with helium. Irradiation of ampoules was carried out in the loop channel of WWRK reactor (Almaty, Kazakhstan) during 223 days at 6 MW power. After irradiation light-colored pebbles became grey-colored due to structure changes which generation of grey-colored inclusions (lithium oxide) with low density and microhardness. There is a radiation softening of lithium ceramic and that effect is higher for lower irradiation temperature 760 K than for 920 K. The value of maximum permissible load (pebble crash limit) at that is low and comprises ˜37.9 N. The content of residual tritium is higher for ceramic irradiated at 760 K (6.6 ± 0.6 × 10 11 Bq/kg) than for ceramic irradiated at 920 K (17 ± 3 × 10 10 Bq/kg). The size change indicates that pebble increase more after irradiation at 760 K than at 920 K where the bigger portion of tritium leaves the pebble. X-ray analysis shows radiation modification of Li 2TiO 3 + 5 mol% TiO 2 phase composition and generation of new phases: LiTi 2O 4, LiTiO 2 and Li 4Ti 5O 12.

  15. Effects of neutron irradiation on glass ceramics as pressure-less joining materials for SiC based components for nuclear applications

    NASA Astrophysics Data System (ADS)

    Ferraris, M.; Casalegno, V.; Rizzo, S.; Salvo, M.; Van Staveren, T. O.; Matejicek, J.

    2012-10-01

    This paper reports on the microstructure and properties of two glass-ceramics based on SiO2-Al2O3-MgO (SAMg) and SiO2-Al2O3-Y2O3 (SAY), which have been designed to be used as pressure-less low activation joining materials for SiC/SiC and SiC based components for nuclear applications. Glass-ceramic pellets (SAY and SAMg) were irradiated for approximately 1 year in the reactor core of the LVR-15 research reactor at Nuclear Research Institute Rez, Czech Republic, at about 50 °C, 6.92 × 1024 n/m2 (E > 1 MeV, about 1 dpa in steel); SiC/SiC composites joined by SAY were irradiated about 1 year at High Flux Reactor (HFR), Petten, The Netherlands, 550 °C, 9-11 × 1024 n/m2 (E > 1 MeV, about 1.4-1.8 dpa in C), 600 °C, 16-22 × 1024 n/m2 (E > 1 MeV, about 2.6-3.3 dpa in C) and 820 °C 31-32 × 1024 n/m2(E > 1 MeV, about 5 dpa in C). Optical microscopy with image analysis and scanning electron microscopy (SEM) with X-ray microanalysis (EDS) were used to investigate the glass-ceramics morphology and composition, showing a remarkable similarity before and after neutron irradiation for both glass-ceramics. Comparison of bending strength for irradiated and non-irradiated SAY joined SiC/SiC indicate that the mechanical strength is unaffected by irradiation at these conditions.

  16. Development of a monolithic ferrite memory array

    NASA Technical Reports Server (NTRS)

    Heckler, C. H., Jr.; Bhiwandker, N. C.

    1972-01-01

    The results of the development and testing of ferrite monolithic memory arrays are presented. This development required the synthesis of ferrite materials having special magnetic and physical characteristics and the development of special processes; (1) for making flexible sheets (laminae) of the ferrite composition, (2) for embedding conductors in ferrite, and (3) bonding ferrite laminae together to form a monolithic structure. Major problems encountered in each of these areas and their solutions are discussed. Twenty-two full-size arrays were fabricated and fired during the development of these processes. The majority of these arrays were tested for their memory characteristics as well as for their physical characteristics and the results are presented. The arrays produced during this program meet the essential goals and demonstrate the feasibility of fabricating monolithic ferrite memory arrays by the processes developed.

  17. High-Q ferrite-tuned cavity

    SciTech Connect

    Earley, L.M.; Thiessen, H.A.; Carlini, R.D.; Potter, J.M.

    1983-08-01

    Rapid-cycling proton synchrotrons, such as the proposed LAMPF II accelerator, require approximately 10 MV per turn rf with 17% tuning range near 50 MHz. The traditional approach to ferrite-tuned cavities uses a ferrite which is longitudinally biased (rf magnetic field parallel to bias field). This method leads to unacceptably high losses in the ferrite. At Los Alamos, we are developing a cavity with transverse bias (rf magnetic field perpendicular to the bias field) that makes use of the tensor permeability of the ferrite. Initial tests of a small (10-cm-diam) quarter-wave singly re-entrant cavity tuned by several different ferrites indicate that the losses in the ferrite can be made negligible compared with the losses due to the surface resistivity of the copper cavity.

  18. Recent status and improvement of reduced-activation ferritic-martensitic steels for high-temperature service

    DOE PAGESBeta

    Tan, L.; Katoh, Y.; Tavassoli, A. -A. F.; Henry, J.; Rieth, M.; Sakasegawa, H.; Tanigawa, H.; Huang, Q.

    2016-07-26

    Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. Additionally, to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti,more » X = C/N) precipitates and reducing coarse M23C6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. We present and compare limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic with data for F82H and Eurofer97 irradiated up to ~70 displacements per atom at ~300–325 °C.« less

  19. Recent status and improvement of reduced-activation ferritic-martensitic steels for high-temperature service

    NASA Astrophysics Data System (ADS)

    Tan, L.; Katoh, Y.; Tavassoli, A.-A. F.; Henry, J.; Rieth, M.; Sakasegawa, H.; Tanigawa, H.; Huang, Q.

    2016-10-01

    Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. In addition to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti, X = C/N) precipitates and reducing coarse M23C6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. Limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic are presented and compared with data for F82H and Eurofer97 irradiated up to ∼70 displacements per atom at ∼300-325 °C.

  20. Effect of neutron irradiation on defect evolution in Ti3SiC2 and Ti2AlC

    SciTech Connect

    Tallman, Darin J.; He, Lingfeng; Garcia-Diaz, Brenda L.; Hoffman, Elizabeth N.; Kohse, Gordon; Sindelar, Robert L.; Barsoum, Michel W.

    2015-10-23

    Here, we report on the characterization of defects formed in polycrystalline Ti3SiC2 and Ti2AlC samples exposed to neutron irradiation – up to 0.1 displacements per atom (dpa) at 350 ± 40 °C or 695 ± 25 °C, and up to 0.4 dpa at 350 ± 40 °C. Black spots are observed in both Ti3SiC2 and Ti2AlC after irradiation to both 0.1 and 0.4 dpa at 350 °C. After irradiation to 0.1 dpa at 695 °C, small basal dislocation loops, with a Burgers vector of b = 1/2 [0001] are observed in both materials. At 9 ± 3 and 10 ± 5 nm, the loop diameters in the Ti3SiC2 and Ti2AlC samples, respectively, were comparable. At 1 × 1023 loops/m3, the dislocation loop density in Ti2AlC was ≈1.5 orders of magnitude greater than in Ti3SiC2, at 3 x 1021 loops/m3. After irradiation at 350 °C, extensive microcracking was observed in Ti2AlC, but not in Ti3SiC2. The room temperature electrical resistivities increased as a function of neutron dose for all samples tested, and appear to saturate in the case of Ti3SiC2. The MAX phases are unequivocally more neutron radiation tolerant than the impurity phases TiC and Al2O3. Based on these results, Ti3SiC2 appears to be a more promising MAX phase candidate for high temperature nuclear applications than Ti2AlC.

  1. Multifunctionality of nanocrystalline lanthanum ferrite

    NASA Astrophysics Data System (ADS)

    Rai, Atma; Thakur, Awalendra K.

    2016-05-01

    Nanocrystalline lanthanum ferrite has been synthesized by adopting modified Pechini route. No evidence of impurity or secondary phase has been detected up to the detection of error limit of X-ray diffractometer (XRD). Rietveld refinement of X-ray diffraction pattern reveals orthorhombic crystal system with space group Pnma (62).Crystallite size and lattice strain was found to be ˜42.8nm and 0.306% respectively. Optical band gap was found to be 2.109 eV, by UV-Visible diffused reflectance spectrum (DRS). Brunauer-Emmet-Teller (BET) surface area was found to be ˜3.45 m2/g. Magnetization-hysteresis (M-H) loop was recorded at room temperature (300K) reveals weak ferromagnetism in Nanocrystalline lanthanum ferrite. The weak ferromagnetism in lanthanum ferrite is due to the uncompensated antiferromagnetic spin ordering. Ferroelectric loop hysteresis observed at room temperature at 100Hz depicts the presence of ferroelectric ordering in LaFeO3.Simultanious presence of magnetic and ferroelectric ordering at room temperature makes it suitable candidate of Multiferroic family.

  2. Neutron irradiation of beryllium pebbles

    SciTech Connect

    Gelles, D.S.; Ermi, R.M.; Tsai, H.

    1998-03-01

    Seven subcapsules from the FFTF/MOTA 2B irradiation experiment containing 97 or 100% dense sintered beryllium cylindrical specimens in depleted lithium have been opened and the specimens retrieved for postirradiation examination. Irradiation conditions included 370 C to 1.6 {times} 10{sup 22} n/cm{sup 2}, 425 C to 4.8 {times} 10{sup 22} n/cm{sup 2}, and 550 C to 5.0 {times} 10{sup 22} n/cm{sup 2}. TEM specimens contained in these capsules were also retrieved, but many were broken. Density measurements of the cylindrical specimens showed as much as 1.59% swelling following irradiation at 500 C in 100% dense beryllium. Beryllium at 97% density generally gave slightly lower swelling values.

  3. The effects of neutron irradiation on shear properties at the monolayered PyC and the multilayered PyC/SiC interfaces of SiC/SiC composites

    SciTech Connect

    Nozawa, Takashi; Katoh, Yutai; Snead, Lance Lewis

    2007-01-01

    The effect of neutron irradiation on mechanical properties at the fiber/matrix interface of SiC/SiC composites was evaluated. The materials investigated were Hi-Nicalon Type-S fiber reinforced chemically vapor infiltrated SiC matrix composites with varied interphases: monolayered pyrolytic carbon (PyC) or multilayered PyC/SiC. The neutron fluence was 7.7 1025 n/m2 (E>0.1 MeV), and the irradiation temperature was 800 C. Interfacial shear properties were evaluated by the fiber push-out test method. A modified shear-lag model was applied to analyze the interfacial shear parameters. Test results indicate that the interfacial debond shear strength and the interfacial friction stress for the multilayer composites were significantly degraded by irradiation. Nevertheless, the multilayer composites retained sufficient interfacial shear properties so that overall composite strength after neutron irradiation was unaffected. The actual mechanism of interphase property decrease for the multilayer composites is unknown. The interfacial shear properties of the irradiated monolayer composites contrarily appear unaffected.

  4. Beam induced heating of ferrite magnets

    SciTech Connect

    van Asselt, W.K.; Lee, Y.Y.

    1991-01-01

    Alerted by impedance measurements of ferrite kicker magnets and by apparent beam induced pressure increase in the neighborhood of window frame kicker magnets, bench measurements of magnet heating have been done. They confirmed the necessity of interrupting the ferrite yoke. Another method, which can be applied for existing magnets, will be described. 1 ref., 4 figs.

  5. Exchange coupled ferrite nanocomposites through chemical synthesis.

    PubMed

    Dai, Qilin; Patel, Ketan; Ren, Shenqiang

    2016-08-16

    Exchange coupling between magnetically hard and soft phases has the potential to yield a large gain in the energy product. In this work, we present a scalable chemical synthetic route to produce magnetic iron oxide based nanocomposites, consisting of cobalt ferrite (CoFe2O4) and strontium ferrite (SrFe12O19) components. PMID:27476744

  6. Effect of Cr content on the nanostructural evolution of irradiated ferritic/martensitic alloys: An object kinetic Monte Carlo model

    NASA Astrophysics Data System (ADS)

    Chiapetto, M.; Malerba, L.; Becquart, C. S.

    2015-10-01

    Self-interstitial cluster diffusivity in Fe-Cr alloys, model materials for high-Cr ferritic/martensitic steels, is known to be reduced in a non-monotonic way as a function of Cr concentration: it first decreases, then increases. This non-monotonic behaviour is caused by a relatively long-ranged attractive interaction between Cr atoms and crowdions and correlates well with the experimentally observed swelling in these alloys under neutron irradiation, also seen to first decrease and then increase with increasing Cr content, under comparable irradiation conditions. Moreover, recent studies reveal that C atoms dispersed in the Fe matrix form under irradiation complexes with vacancies which, in turn, act as trap for one-dimensionally migrating self-interstitial clusters. The mobility of one-dimensional migrating clusters is considered key to determine swelling susceptibility. However, no model has ever been built that quantitatively describes the dependence of swelling on Cr content, allowing for the presence of C in the matrix. In this work we developed physically-based sets of parameters for object kinetic Monte Carlo (OKMC) simulations intended to study the nanostructure evolution under irradiation in Fe-Cr-C alloys. The nanostructural evolution in Fe-C and in four Fe-Cr-C alloys (containing 2.5, 5, 9 and 12 wt.% Cr) neutron irradiated up to ∼0.6 dpa at 563 K was simulated according to the model and reference experiments were reproduced. Our model shows that the SIA cluster reduced mobility has a major influence on the nanostructural evolution: it increases the number of vacancy-SIA recombinations and thus leads to the suppression of voids formation. This provides a clear framework to interpret the non-monotonic dependence of swelling in Fe-Cr alloys versus Cr content. Our model also suggests that the amount of C in the matrix has an equally important role: high amounts of it may counteract the beneficial effect that Cr has in reducing swelling.

  7. MICROSTRUCTURAL SUMMARY OF ODS FERRITIC ALLOYS (14YW, 14YWT, 12YWT, MA957FR, PM2000) AND RAFM STEELS (F82H MOD.3-CW, EUROFER97) FROM JP27 IN-SITU HE INJECTION (ISHI) EXPERIEMNT AT 500C

    SciTech Connect

    Jung, Hee Joon; Edwards, Danny J.; Kurtz, Richard J.; Odette, G Robert; Wu, Yuan; Yamamoto, Takuya

    2015-09-22

    A TEM characterization of various ferritic based alloys has been conducted to document the changes in the microstructure under neutron irradiation and the impact of high levels of He injection. Microstructural features such as dislocation loops, network dislocations, He bubbles and voids were characterized in five ODS alloys, 14YW, 14YWT, 12YWT, MA957Fr, PM2000, and two RAFM steels, F82H mod.3+CW and Eurofer. The total neutron dose was 21.2 dpa and the total He levels were 1230 appm injected into an ~6 µm uniform region below the surface of the sample. The results indicated that He injection has a profound impact on the microstructural evolution of these alloys, producing dramatic changes in the dislocation structure and cavity distribution that are closely related to the size, density and chemistry of the oxide particles, or the lack thereof in the case of the RADM alloys.

  8. Structural analysis of emerging ferrite: Doped nickel zinc ferrite

    SciTech Connect

    Kumar, Rajinder; Kumar, Hitanshu; Singh, Ragini Raj; Barman, P. B.

    2015-08-28

    Ni{sub 0.6-x}Zn{sub 0.4}Co{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.033, 0.264) nanoparticles were synthesized by sol-gel method and annealed at 900°C. Structural properties of all prepared samples were examined with X-ray diffraction (XRD). The partial formation of hematite (α-Fe{sub 2}O{sub 3}) secondary phase with spinel phase cubic structure of undoped and cobalt doped nickel zinc ferrite was found by XRD peaks. The variation in crystallite size and other structural parameters with cobalt doping has been calculated for most prominent peak (113) of XRD and has been explained on the basis of cations ionic radii difference.

  9. Ferrite HOM Absorber for the RHIC ERL

    SciTech Connect

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  10. Ferrite insertion at Recycler Flying Wire System

    SciTech Connect

    K.Y. Ng

    2004-02-27

    Ferrite rods are installed inside the flying-wire cavity of the Recycler Ring and at entrance and exit beam pipes in order to absorb high-frequency electromagnetic waves excited by the beam. However, these rods may also deteriorate the vacuum pressure of the ring. An investigation is made to analyze the necessity of the ferrite rods at the entrance and exit beam pipes.

  11. Development and application of ferrite materials for low temperature co-fired ceramic technology

    NASA Astrophysics Data System (ADS)

    Zhang, Huai-Wu; Li, Jie; Su, Hua; Zhou, Ting-Chuan; Long, Yang; Zheng, Zong-Liang

    2013-11-01

    Development and application of ferrite materials for low temperature co-fired ceramic (LTCC) technology are discussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 °C. These ferrite materials are research focuses and are applied in many ways in electronics.

  12. Rapid phase synthesis of nanocrystalline cobalt ferrite

    SciTech Connect

    Shanmugavel, T.; Raj, S. Gokul; Rajarajan, G.; Kumar, G. Ramesh

    2014-04-24

    Synthesis of single phase nanocrystalline Cobalt Ferrite (CoFe{sub 2}O{sub 4}) was achieved by single step autocombustion technique with the use of citric acid as a chelating agent in mono proportion with metal. Specimens prepared with this method showed significantly higher initial permeability's than with the conventional process. Single phase nanocrystalline cobalt ferrites were formed at very low temperature. Surface morphology identification were carried out by transmission electron microscopy (TEM) analysis. The average grain size and density at low temperature increased gradually with increasing the temperature. The single phase formation is confirmed through powder X-ray diffraction analysis. Magnetization measurements were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited typical magnetic behaviors. Temperature dependent magnetization results showed improved behavior for the nanocrystalline form of cobalt ferrite when compared to the bulk nature of materials synthesized by other methods.

  13. Metallization of ferrite ceramic couplings. Final report

    SciTech Connect

    Burden, J

    1992-06-01

    Tests were conducted to determine the optimum sputtering conditions for which the strongest metallization adherence could be achieved for the ferrite safing wheel assemblies. The conditions were varied through four separate test runs with a fifth verification run conducted using parameters selected from the first four runs. The parameters tested were the effects of etching, precleaning, chamber pressures, plating materials, plating thickness, soldering pressures, and cooling rates. The results increased the strength of the metallization to two pounds, well in excess of the required one pound minimum. It was also determined that the gold should be sputtered on and not thermally deposited, which caused cracking in the ferrite material.

  14. Cation distributions on rapidly solidified cobalt ferrite

    NASA Technical Reports Server (NTRS)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  15. A preliminary ferritic-martensitic stainless steel constitution diagram

    SciTech Connect

    Balmforth, M.C.; Lippold, J.C.

    1998-01-01

    This paper describes preliminary research to develop a constitution diagram that will more accurately predict the microstructure of ferritic and martensitic stainless steel weld deposits. A button melting technique was used to produce a wide range of compositions using mixtures of conventional ferritic and martensitic stainless steels, including types 403, 409, 410, 430, 439 and 444. These samples were prepared metallographically, and the vol-% ferrite and martensite was determined quantitatively. In addition, the hardness and ferrite number (FN) were measured. Using this data, a preliminary constitution diagram is proposed that provides a more accurate method for predicting the microstructures of arc welds in ferritic and martensitic stainless steels.

  16. Atomic engineering of mixed ferrite and core-shell nanoparticles.

    PubMed

    Morrison, Shannon A; Cahill, Christopher L; Carpenter, Everett E; Calvin, Scott; Harris, Vincent G

    2005-09-01

    Nanoparticulate ferrites such as manganese zinc ferrite and nickel zinc ferrite hold great promise for advanced applications in power electronics. The use of these materials in current applications requires fine control over the nanoparticle size as well as size distribution to maximize their packing density. While there are several techniques for the synthesis of ferrite nanoparticles, reverse micelle techniques provide the greatest flexibility and control over size, crystallinity, and magnetic properties. Recipes for the synthesis of manganese zinc ferrite, nickel zinc ferrite, and an enhanced ferrite are presented along with analysis of the crystalline and magnetic properties. Comparisons are made on the quality of nanoparticles produced using different surfactant systems. The importance of various reaction conditions is explored with a discussion on the corresponding effects on the magnetic properties, particle morphology, stoichiometry, crystallinity, and phase purity.

  17. Thermodynamic studies on lithium ferrites

    SciTech Connect

    Rakshit, S.K.; Parida, S.C.; Naik, Y.P.; Chaudhary, Ziley Singh; Venugopal, V.

    2011-05-15

    Thermodynamic studies on ternary oxides of Li-Fe-O systems were carried out using differential scanning calorimetry, Knudsen effusion mass spectrometry, and solid-state electrochemical technique based on fluoride electrolyte. Heat capacities of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined in the temperature range 127-861 K using differential scanning calorimetry. Gibbs energies of formation of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined using Knudsen effusion mass spectrometry and solid-state galvanic cell technique. The combined least squares fits can be represented as {Delta}{sub f}G{sub m}{sup o}(LiFe{sub 5}O{sub 8},s,T)/kJ mol{sup -1} ({+-}6)=-2341+0.6764(T/K) (588{<=}T/K{<=}971) {Delta}{sub f}G{sub m}{sup o}(LiFeO{sub 2},s,T)/kJ mol{sup -1} ({+-}3)=-708+0.1656(T/K) (569{<=}T/K{<=}1021) The temperature independent term of the above equations represents {Delta}{sub f}H{sup o}{sub m}(T{sub av}) and temperature dependent term represents negative change in entropy of the respective compounds. Thermodynamic analysis shows that LiFe{sub 5}O{sub 8}(s) is more stable compared to LiFeO{sub 2}(s). -- Graphical abstract: Comparison of {Delta}{sub f}G{sub m}{sup o}(T) of lithium ferrites determined using different techniques. Display Omitted Highlights: {yields} Thermodynamic studies on Li-Fe-O system using DSC, KEQMS and galvanic cell. {yields} Heat capacities of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined using DSC 127-861 K. {yields} {Delta}{sub f}G{sup o}{sub m} of these compounds were determined and compared. {yields} Thermodynamic tables for LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were constructed.

  18. Tantalum modified ferritic iron base alloys

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  19. Design of ferrite-tuned accelerator cavities using perpendicular-biased high-Q ferrites

    SciTech Connect

    Kaspar, K.

    1984-11-01

    Microwave ferrites with dc bias fields perpendicular to the rf fields exhibit magnetic and dielectric quality factors 1 order of magnitude above that of ferrites used in ferrite-tuned synchrotron accelerating cavities built in the past. For the LAMPF II project, these ferrites appear to allow the design of synchrotron cavities with high gap voltages and high efficiency. A simple coaxial quarter-wave-resonator geometry, first considered only as a model for preliminary studies, turned out to be a good basis for the solution of most technical problems such as generation of the bias field, cooling of the ferrites, and installation of a generous high-voltage gap design. Two quarter-wave resonators combined to form one accelerating unit of about 2.5-m length and 0.6-m diameter should be capable of delivering 120 kV of accelerating voltage in the tuning range 50-60 MHz, up to 200 kV in the range 59-60 MHz. The main advantage of the given resonator design is its full rotational symmetry, which allows calculation and optimization of all electrical properties with maximum reliability.

  20. Ferritization treatment of copper in soil by electrokinetic remediation.

    PubMed

    Kimura, Tomoyuki; Takase, Ken-Ichi; Terui, Norifumi; Tanaka, Shunitz

    2007-05-17

    The usefulness of the combined use of the electrokinetic (EK) remediation and a ferrite treatment zone (FTZ) was demonstrated for a treatment of the contaminated soil with heavy metal ions. Copper ions in contaminated soil were transferred into the FTZ by the EK technology and were ferritized in this system. The distribution of copper in a migration chamber after EK treatment with FTZ for 48h showed the large difference in the total and eluted concentration of copper. This indicated that copper ions transferred by EK into the FTZ were ferritized there with ferrite reagent in soil alkalified by EK process. The copper-ferrite compound, which was not dissolved with diluted acid, was retained in the FTZ and accumulated there. The ratio of the ferritized amount of copper against total copper was 92% in the EK process with FTZ after 48 h. PMID:17374444

  1. Cold worked ferritic alloys and components

    DOEpatents

    Korenko, Michael K.

    1984-01-01

    This invention relates to liquid metal fast breeder reactor and steam generator precipitation hardening fully ferritic alloy components which have a microstructure substantially free of the primary precipitation hardening phase while having cells or arrays of dislocations of varying population densities. It also relates to the process by which these components are produced, which entails solution treating the alloy followed by a final cold working step. In this condition, the first significant precipitation hardening of the component occurs during high temperature use.

  2. Substituted barium ferrites; sources of anisotropy

    NASA Astrophysics Data System (ADS)

    Morrish, A. H.; Zhou, X. Z.; Yang, Zheng; Zeng, Hua-Xian

    1994-12-01

    The substituted barium ferrites BaFe12-2 xCo x Sn x O19 (0 ≤ x ≤ 1.4) and BaFe1-2xCo x O19 (0 ≤ x ≤ 0.9) have been studied. The site occupancies, as determined from Mössbauer spectra, have been used to interpret the changes in the magnetization and in the crystalline anisotropy.

  3. Non linear effects in ferrite tuned cavities

    SciTech Connect

    Goren, Y.; Mahale, N.; Walling, L.; Enegren, T.; Hulsey, G. ); Yakoviev, V.; Petrov, V. )

    1993-05-01

    The phenomenon of dependence of the resonance shape and frequency on the RF power level in perpendicular biased ferrite-tuned cavities has been observed by G. Hulsey and C. Friedrichs in the SSC test cavity experiment. This paper presents a theoretical as well as numerical analysis of this phenomenon and compares the results with experimental data. The effect of this nonlinearity on the SSC low energy booster prototype cavity is discussed.

  4. Properties of ferrites important to their friction and wear behavior

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1983-01-01

    Environmental, chemical and crystallographical effects on the fundamental nature on friction and wear of the ferrites in contact with metals, magnetic tapes and themselves are reviewed. The removal of adsorbed films from the surfaces of ferrites results in very strong interfacial adhesion and high friction in ferrite to metal and ferrite to magnetic tape contacts. The metal ferrite bond at the interface is primarily a chemical bond between the metal atoms and the large oxygen anions in the ferrite surface, and the strength of these bonds is related to the oxygen to metal bond strength in the metal oxide. The more active the metal, the higher is the coefficient of friction. Not only under adhesive conditions, but also under abrasive conditions the friction and wear properties of ferrites are related to the crystallographic orientation. With ferrite to ferrite contact the mating of highest atomic density (most closely packed) direction on matched crystallographic planes, that is, 110 directions on /110/planes, results in the lowest coefficient of friction.

  5. Tunable Dielectric Properties of Ferrite-Dielectric Based Metamaterial

    PubMed Central

    Bi, K.; Huang, K.; Zeng, L. Y.; Zhou, M. H.; Wang, Q. M.; Wang, Y. G.; Lei, M.

    2015-01-01

    A ferrite-dielectric metamaterial composed of dielectric and ferrite cuboids has been investigated by experiments and simulations. By interacting with the electromagnetic wave, the Mie resonance can take place in the dielectric cuboids and the ferromagnetic precession will appear in the ferrite cuboids. The magnetic field distributions show the electric Mie resonance of the dielectric cuboids can be influenced by the ferromagnetic precession of ferrite cuboids when a certain magnetic field is applied. The effective permittivity of the metamaterial can be tuned by modifying the applied magnetic field. A good agreement between experimental and simulated results is demonstrated, which confirms that these metamaterials can be used for tunable microwave devices. PMID:25993433

  6. Nanosized copper ferrite materials: Mechanochemical synthesis and characterization

    SciTech Connect

    Manova, Elina; Tsoncheva, Tanya; Paneva, Daniela; Popova, Margarita; Velinov, Nikolay; Kunev, Boris; Tenchev, Krassimir; Mitov, Ivan

    2011-05-15

    Nanodimensional powders of cubic copper ferrite are synthesized by two-steps procedure of co-precipitation of copper and iron hydroxide carbonates, followed by mechanochemical treatment. X-ray powder diffraction, Moessbauer spectroscopy and temperature-programmed reduction are used for the characterization of the obtained materials. Their catalytic behavior is tested in methanol decomposition to hydrogen and CO and total oxidation of toluene. Formation of nanosized ferrite material is registered even after one hour of milling time. It is established that the prolonging of treatment procedure decreases the dispersion of the obtained product with the appearance of Fe{sub 2}O{sub 3}. It is demonstrated that the catalytic behavior of the samples depends not only on their initial phase composition, but on the concomitant ferrite phase transformations by the influence of the reaction medium. -- Graphical abstract: It is demonstrated that the catalytic behavior of the obtained copper ferrites depends not only on their initial phase composition, but on the concomitant phase transformations by the influence of the reaction medium. Display Omitted Highlights: {yields} Two-step co-precipitation-ball-milling procedure for copper ferrites preparation. {yields} The phase composition of ferrites depends on the milling duration. {yields} Ferrites transforms under the reaction medium, which affects their catalytic behavior. {yields} Ferrites decompose to magnetite and carbides during methanol decomposition. {yields} Agglomeration and further crystallization of ferrite occur during toluene oxidation.

  7. Ferrite microwave electronics Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Reed, W. E.

    1980-07-01

    Research reports on single crystals, thin films, dielectrics, semiconductor devices, integrated circuits, phase shifters, and waveguide components are cited. Studies on the microwave properties of ferrites are included.

  8. Massive strontium ferrite ingestion without acute toxicity.

    PubMed

    Kirrane, Barbara M; Nelson, Lewis S; Hoffman, Robert S

    2006-11-01

    Ingestion of strontium ferrite is previously unreported. We document absorption of strontium without acute toxicity. A 22 year-old schizophrenic man was brought to hospital after he was witnessed to pulverize and ingest flexible adhesive magnets, which later were identified as strontium ferrite. Other than auditory hallucinations his vital signs, physical examination, ECG and routine laboratories were unremarkable. Abdominal radiographs revealed diffuse radiopaque material. He was treated with whole bowel irrigation with polyethylene glycol electrolyte lavage solution (PEG-ELS) until radiographically cleared. His initial blood and urine strontium levels were 2900 microg/l and 15,000 microg/l, respectively (reference range for urine: <240 microg/l, occupational threshold 800 microg/l). A repeat urine level one week later was 370 microg/l. His hospital course was complicated by bacteraemia secondary to a thrombophlebitis at the site of the intravenous catheter, and the patient was treated with intravenous and oral antibiotics. He remained otherwise asymptomatic and was discharged to a psychiatric unit approximately 3 weeks later. Although clearly absorbed, strontium ferrite does not appear to produce acute toxicity. Delayed, and or chronic toxicity cannot be excluded based on this report.

  9. Preferential spin canting in nanosize zinc ferrite

    NASA Astrophysics Data System (ADS)

    Pandey, Brajesh; Litterst, F. J.; Baggio-Saitovitch, E. M.

    2015-07-01

    Zinc ferrite nanoparticles powder with average size of 10.0±0.5 nm was synthesized by the citrate precursor route. We studied the structural and magnetic properties using X-ray diffraction, vibrating sample magnetometry and Mössbauer spectroscopy. X-ray diffraction patterns show that the synthesized zinc ferrite possesses good spinel structure. Both Mössbauer and magnetization data indicate superparamagnetic ferrimagnetic particles at room temperature. The magnetic behavior is determined by a considerable degree of cation inversion with FeIII in tetrahedral A-sites. Mössbauer spectroscopy at low temperature and in high applied magnetic field reveals that A-site spins are aligned antiparallel to the applied field with some possible angular scatter whereas practically all octahedral B-site spins are canted contrasting some earlier reported partial B-site spin canting in nanosize zinc ferrite. Deviations from the antiferromagnetic arrangement of B-site spins are supposed to be caused by magnetic frustration effects.

  10. Ferritic steel melt and FLiBe/steel experiment : melting ferritic steel.

    SciTech Connect

    Troncosa, Kenneth P.; Smith, Brandon M.; Tanaka, Tina Joan

    2004-11-01

    In preparation for developing a Z-pinch IFE power plant, the interaction of ferritic steel with the coolant, FLiBe, must be explored. Sandia National Laboratories Fusion Technology Department was asked to drop molten ferritic steel and FLiBe in a vacuum system and determine the gas byproducts and ability to recycle the steel. We tried various methods of resistive heating of ferritic steel using available power supplies and easily obtained heaters. Although we could melt the steel, we could not cause a drop to fall. This report describes the various experiments that were performed and includes some suggestions and materials needed to be successful. Although the steel was easily melted, it was not possible to drip the molten steel into a FLiBe pool Levitation melting of the drop is likely to be more successful.

  11. Modeling non-saturated ferrite-based devices: Application to twin toroid ferrite phase shifters

    NASA Astrophysics Data System (ADS)

    Le Gouellec, A.; Vérissimo, G.; Laur, V.; Queffelec, P.; Albert, I.; Girard, T.

    2016-08-01

    This article describes a new set of tools developed to improve the conception and modeling of non-saturated ferrite-based devices such as twin toroid phase shifters. These new simulation tools benefit from a generalized permeability tensor model able to describe the permeability tensor of a ferrite sample whatever its magnetization state. This model is coupled to a homemade 3D multi-scale magnetostatic analysis program, which describes the evolution of the magnetization through the definition of a hysteresis loop in every mesh cell. These computed spectra are then integrated into 3D electromagnetic simulation software that retains the spatial variations of the ferrite properties by using freshly developed macro programming functions. This new approach allows the designers to accurately model complex ferrite devices such as twin toroid phase shifters. In particular, we demonstrated a good agreement between simulated and measured phase shifts as a function of applied current values with a predicted maximum phase shift of 0.96 times the measured value.

  12. Intragranular ferrite nucleation in medium-carbon vanadium steels

    SciTech Connect

    Ishikawa, Fusao; Takahashi, Toshihiko ); Ochi, Tatsurou . Muroran R D Lab.)

    1994-05-01

    In this study, the mechanism of intragranular ferrite nucleation is investigated. It is found that intragranular ferrite idiomorphs'' nucleate at vanadium nitrides which precipitate at manganese sulfide particles during cooling in the austenite region. It is observed that intragranular ferrite has the Baker-Nutting orientation relationship with vanadium nitride which precipitated at manganese sulfide. According to classical nucleation theory, the proeutectoid ferrite nucleation rate depends on the following factors: (1) the driving free energy for ferrite nucleation, (2) the diffusivity of carbon atoms in austenite, and (3) the increase in the interfacial energy associated with ferrite nucleation. In the Baker-Nutting orientation relationship, the lattice mismatch across the habit planes is likely to be very small. Depleted zones of solute atoms such as vanadium are assumed to be formed in the austenite matrix around precipitates. The effect of the depleted zones on factors (1) and (2) is estimated thermodynamically and it is proved that those effects are negligibly small. Thus, the authors conclude that the most important factor in nucleation kinetics of intragranular ferrite is the formation of precipitates which can develop coherent, low energy interfaces with ferrite.

  13. Adsorption of oxygen and 1-butene on magnesium ferrite

    SciTech Connect

    Samuilova, O.K.; Kozlova, M.M.; Yagodovskii, V.D.

    1986-08-01

    The kinetics of the adsorption of oxygen and 1-butene on magnesium ferrite was studied. Conductometry and thermal desorption methods were used to investigate the adsorption of oxygen on magnesium ferrite. Two forms of adsorbed oxygen were found. The formation of these forms affects the kinetics of the adsorption of 1-butene.

  14. Electrical transport behavior of nonstoichiometric magnesium-zinc ferrite

    SciTech Connect

    Ghatak, S.; Sinha, M.; Meikap, A.K.; Pradhan, S.K.

    2010-08-15

    This paper presents the direct current conductivity, alternate current conductivity and dielectric properties of nonstoichiometric magnesium-zinc ferrite below room temperature. The frequency exponent (s) of conductivity shows an anomalous temperature dependency. The magnitude of the temperature exponent (n) of dielectric permittivity strongly depends on frequency and its value decreases with increasing frequency. The grain boundary contribution is dominating over the grain contribution in conduction process and the temperature dependence of resistance due to grain and grain boundary contribution exhibits two activation regions. The ferrite shows positive alternating current magnetoconductivity. The solid state processing technique was used for the preparation of nanocrystalline ferrite powder from oxides of magnesium, zinc and iron. The X-ray diffraction methods were used in determining the structure and composition of obtained ferrite, while multimeter, impedance analyzer, liquid nitrogen cryostat and electromagnet were used in the study of conducting and dielectric properties of ferrite.

  15. Cobalt ferrite nanoparticles under high pressure

    SciTech Connect

    Saccone, F. D.; Ferrari, S.; Grinblat, F.; Bilovol, V.; Errandonea, D.

    2015-08-21

    We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20–27 GPa to 7.5–12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B{sub 0} = 204 GPa) is considerably larger than the value previously reported for bulk CoFe{sub 2}O{sub 4} (B{sub 0} = 172 GPa). In addition, when the pressure medium becomes non-hydrostatic and deviatoric stresses affect the experiments, there is a noticeable decrease of the compressibility of the studied sample (B{sub 0} = 284 GPa). After decompression, the cobalt ferrite lattice parameter does not revert to its initial value, evidencing a unit cell contraction after pressure was removed. Finally, Raman spectroscopy provides information on the pressure dependence of all Raman-active modes and evidences that cation inversion is enhanced by pressure under non-hydrostatic conditions, being this effect not fully reversible.

  16. Soft ferrite cores characterization for integrated micro-inductors

    NASA Astrophysics Data System (ADS)

    Nguyen, Yen Mai; Bourrier, David; Charlot, Samuel; Valdez-Nava, Zarel; Bley, Vincent; Combettes, Céline; Lopez, Thomas; Laur, Jean-Pierre; Brunet, Magali

    2014-10-01

    Low-profile soft ferrite films constitute a competitive solution for the integration of micro-inductors on silicon in low-power medium frequency dc-dc conversion applications. The high resistivity of soft ferrites is indeed a major advantage for operating frequencies in the range of 5‒10 MHz. We have studied several soft ferrites, including commercial ferrite films and ferrites made in-house. Test inductors were fabricated at a wafer level using micro-machining and assembling techniques. The proposed process is based on a sintered ferrite core placed between thick electroplated copper windings. The low-profile ferrite cores of 1.2  ×  2.6  ×  0.1 mm3 were produced by two methods using green tape-cast films or ferrite powders. This article presents the magnetic characterization of the fabricated ferrite cores, cut and printed in a rectangular shape and sintered at different temperatures. Comparisons are made in order to find the best material for the core that can offer micro-inductors a high inductance in the range of 200-1000 nH at 6 MHz, and that generate the smallest losses. Thanks to a test inductor, it is demonstrated that with a commercial ferrite core, an inductance density of 215 nH mm-2 up to 6 MHz could be reached. Extracted losses at 6 MHz, under 10 mT are in the range of 0.7 to 2.5 W cm-3.

  17. Corrosion behavior of magnetic ferrite coating prepared by plasma spraying

    SciTech Connect

    Liu, Yi; Wei, Shicheng Tong, Hui; Tian, Haoliang; Liu, Ming; Xu, Binshi

    2014-12-15

    Graphical abstract: The saturation magnetization (M{sub s}) of the ferrite coating is 34.417 emu/g while the M{sub s} value of the ferrite powder is 71.916 emu/g. It can be seen that plasma spray process causes deterioration of the room temperature soft magnetic properties. - Highlights: • Spinel ferrite coatings have been prepared by plasma spraying. • The coating consists of nanocrystalline grains. • The saturation magnetization of the ferrite coating is 34.417 emu/g. • Corrosion behavior of the ferrite coating was examined in NaCl solution. - Abstract: In this study, spray dried spinel ferrite powders were deposited on the surface of mild steel substrate through plasma spraying. The structure and morphological studies on the ferrite coatings were carried out using X-ray diffraction, scanning electron microscope and Raman spectroscopy. It was showed that spray dried process was an effective method to prepare thermal spraying powders. The coating showed spinel structure with a second phase of LaFeO{sub 3}. The magnetic property of the ferrite samples were measured by vibrating sample magnetometer. The saturation magnetization (M{sub s}) of the ferrite coating was 34.417 emu/g. The corrosion behavior of coating samples was examined by electrochemical impedance spectroscopy. EIS diagrams showed three corrosion processes as the coating immersed in 3.5 wt.% NaCl solution. The results suggested that plasma spraying was a promising technology for the production of magnetic ferrite coatings.

  18. Radioisotopes produced by neutron irradiation of food.

    PubMed

    Albright, S; Seviour, R

    2016-04-01

    The use of neutrons for cargo interrogation has the potential to drastically improve threat detection. Previous research has focussed on the production of (24)Na, based on the isotopes produced in pharmaceuticals and medical devices. For both the total activity and the ingestion dose we show that a variety of isotopes contribute and that (24)Na is only dominant under certain conditions. The composition of the foods has a strong influence on the resulting activity and ingestion dose suggesting that the pharmaceuticals and medical devices considered initially are not a viable analogue for foodstuffs. There is an energy dependence to the isotopes produced due to the cross-sections of different reactions varying with neutron energy. We show that this results in different isotopes dominating the ingestion dose at different energies, which has not been considered in the previous literature. PMID:26749562

  19. Microstructural origin of the skeletal ferrite morphology of austenitic stainless steel welds

    SciTech Connect

    Brooks, J A; Williams, J C; Thompson, A W

    1982-04-01

    Scanning transmission electron microscopy was conducted on welds exhibiting a variety of skeletal, or vermicular ferrite morphologies in addition to one lathy ferrite morphology. These ferrite morphologies result from primary ferrite solidification followed by a solid state transformation upon cooling. During cooling, a large fraction of the ferrite transforms to austenite leaving a variety of ferrite morphologies. Comparison of composition profiles and alloy partitioning showed both the skeletal and lathy ferrite structures result from a diffusion controlled solid state transformation. However, the overall measured composition profiles of the weld structure are a result of partitioning during both solidification and the subsequent solid state transformation.

  20. Cast Stainless Steel Ferrite and Grain Structure

    SciTech Connect

    Ruud, Clayton O.; Ramuhalli, Pradeep; Meyer, Ryan M.; Mathews, Royce; Diaz, Aaron A.; Anderson, Michael T.

    2012-09-01

    In-service inspection requirements dictate that piping welds in the primary pressure boundary of light-water reactors be subject to a volumetric examination based on the rules contained within the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section XI. The purpose of the inspection is the reliable detection and accurate sizing of service-induced degradation and/or material flaws introduced during fabrication. The volumetric inspection is usually carried out using ultrasonic testing (UT) methods. However, the varied metallurgical macrostructures and microstructures of cast austenitic stainless steel piping and fittings, including statically cast stainless steel and centrifugally cast stainless steel (CCSS), introduce significant variations in the propagation and attenuation of ultrasonic energy. These variations complicate interpretation of the UT responses and may compromise the reliability of UT inspection. A review of the literature indicated that a correlation may exist between the microstructure and the delta ferrite content of the casting alloy. This paper discusses the results of a recent study where the goal was to determine if a correlation existed between measured and/or calculated ferrite content and grain structure in CCSS pipe.

  1. Phase transformation of strontium hexagonal ferrite

    NASA Astrophysics Data System (ADS)

    Bilovol, V.; Martínez-García, R.

    2015-11-01

    The phase transformation of strontium hexagonal ferrite (SrFe12O19) to magnetite (Fe3O4) as main phase and strontium carbonate (SrCO3) as secondary phase is reported here. SrFe12O19 powder was obtained by a heat treatment at 250 °C under controlled oxygen flow. It was observed that the phase transformation occurred when the SrFe12O19 ferrite was heated up to 625 °C in confinement conditions. This transformation took place by a combination of three factors: the presence of stresses in the crystal lattice of SrFe12O19 due to a low synthesis temperature, the reduction of Fe3+ to Fe2+ during the heating up to 625 °C, and the similarity of the coordination spheres of the iron atoms present in the S-block of SrFe12O19 and Fe3O4. X-ray diffraction analysis confirmed the existence of strain and crystal deformation in SrFe12O19 and the absence of them in the material after the phase transformation. Dispersive X-ray absorption spectroscopy and Fe57 Mössbauer spectroscopy provided evidences of the reduction of Fe3+ to Fe2+ in the SrFe12O19 crystal.

  2. R-curve behavior in ferrite ceramics

    SciTech Connect

    Beauchamp, E.K.; Monroe, S.L.

    1990-01-01

    The unusual dependence of the fracture mode of ferrite ceramics on the stress intensity factor in the subcritical crack growth regime was used to create flaws with different concentrations of crack-interface bridges. Flaws with numerous bridges were produced by indenting under dry silicone oil, while flaws with essentially no bridges were produced by indenting under water. Plots of log failure stress as a function of log indenter load for the two types of flaws reflect the differences in bridging. Those with extensive bridging showed pronounced R-curve behavior. The curve for those initially devoid of bridges showed no plateau but did show deviations from a {minus}1/3 slope that correspond to those predicted by Bennison and Lawn for this type of flaw. The ferrite studies was 62.4 Fe{sub 2}O{sub 3} 26.6 MnO, 11.2nO, and .04 V{sub 2}O{sub 5}. 10 figs.

  3. Fast ferrite tuner for the BNL synchrotron light source

    SciTech Connect

    Pivit, E. ); Hanna, S.M.; Keane, J. )

    1991-01-01

    A new type of ferrite tuner has been tested at the BNL. The ferrite tuner uses garnet slabs partially filling a stripline. One of the important features of the tuner is that the ferrite is perpendicularly biased for operation above FMR, thus reducing the magnetic losses. A unique design was adopted to achieve the efficient cooling. The principle of operation of the tuner as well as our preliminary results on tuning a 52 MHz cavity are reported. Optimized conditions under which we demonstrated linear tunability of 80 KHz are described. The tuner's losses and its effect on higher-order modes in the cavity are discussed. 2 refs., 8 figs.

  4. Magnetooptical and crystalline properties of sputtered garnet ferrite film on spinel ferrite buffer layer

    NASA Astrophysics Data System (ADS)

    Furuya, Akinori; Sasaki, Ai-ichiro; Morimura, Hiroki; Kagami, Osamu; Tanabe, Takaya

    2016-09-01

    The purpose of this study is to provide garnet films for volumetric magnetic holography. Volumetric magnetic holography usually employs an easily obtainable short-wavelength laser (visible light, not infrared light) with a large diffraction intensity. Bi-substituted garnet ferrite with a large Faraday rotation is promising for volumetric magnetic holography applications in the visible light region. However, a garnet film without a deteriorated layer must be obtained because a deteriorated layer (minute polycrystalline grains containing an amorphous phase) is formed during the initial deposition on a glass substrate. In particular, the required magnetooptical properties have not been obtained in a thin garnet film (100 nm or less) after annealing (1 h, 700 °C, oxygen atmosphere). Therefore, there is a need for excellent garnet films with the required magnetooptical (MO) properties even if the films are thin. By using a spinel ferrite buffer layer for garnet film deposition, we could obtain a thin garnet film with excellent MO properties. We determined the effect of the initial buffer layer on the crystallinity of the deposited garnet films by observing the film cross section. In addition, we undertook a qualitative estimation of the influence of the crystallinity and optical properties of the garnet film on a glass substrate with a spinel ferrite buffer layer.

  5. Characterization of Irradiated Nanostructured Ferritic Steels

    SciTech Connect

    Bentley, James; Hoelzer, David T; Tanigawa, H.; Yamamoto, T.; Odette, George R.

    2007-01-01

    The past decade has seen the development of a new class of mechanically alloyed (MA) ferritic steels with outstanding mechanical properties that come, at least in part, from the presence of high concentrations (>10{sup 23} m{sup -3}) of Ti-, Y-, and O-enriched nanoclusters (NC). From the outset, there has been much interest in their potential use for applications to fission and proposed fusion reactors, not only because of their attractive high-temperature strength, but also because the presence of NC may result in a highly radiation-resistant material by efficiently trapping point defects to enhance recombination. Of special interest for fusion applications is the potential of NC to trap transmutation-produced He in high concentrations of small cavities, rather than in fewer but larger cavities that lead to greater radiation-induced swelling and other degraded properties.

  6. High strength ferritic alloy-D53

    DOEpatents

    Hagel, William C.; Smidt, Frederick A.; Korenko, Michael K.

    1977-01-01

    A high strength ferritic alloy is described having from about 0.2% to about 0.8% by weight nickel, from about 2.5% to about 3.6% by weight chromium, from about 2.5% to about 3.5% by weight molybdenum, from about 0.1% to about 0.5% by weight vanadium, from about 0.1% to about 0.5% by weight silicon, from about 0.1% to about 0.6% by weight manganese, from about 0.12% to about 0.20% by weight carbon, from about 0.02% to about 0.1% by weight boron, a maximum of about 0.05% by weight nitrogen, a maximum of about 0.02% by weight phosphorous, a maximum of about 0.02% by weight sulfur, and the balance iron.

  7. Transport in Manganese-Zinc Ferrites

    NASA Astrophysics Data System (ADS)

    Singh, David J.; Gupta, M.; Gupta, R.

    2002-03-01

    Density functional studies of the electronic and magnetic structure of the spinel ferrites ZnFe_2O4 and MnFe_2O4 are reported. Correct magnetic orderings are obtained. ZnFe_2O4 is predicted to be a small gap insulator in agreement with experiment. MnFe_2O4 is found to be a low carrier density half-metal in the fully ordered state. However, strong effects on the band structure near the band edges are found upon partial interchange of Fe and Mn atoms. These are above the criterion for disorder induced localization. This indicates that the insulating character may well be due to Anderson localization associated with the intersite Mn-Fe disorder in contrast to the usual picture of a Mott insulating ground state. This possibility is discussed in relation to experimental data.

  8. Ethanol sensor based on nanocrystallite cadmium ferrite

    SciTech Connect

    Gadkari, Ashok B.; Shinde, Tukaram J.; Vasambekar, Pramod N.

    2015-06-24

    The cadmium ferrite was synthesized by oxalate co-precipitation method. The crystal structure and surface morphology were examined by X-ray diffraction and SEM techniques, respectively. The nanocrystallite CdFe{sub 2}O{sub 4} sensor was tested for LPG, Cl{sub 2} and C{sub 2}H{sub 5}OH. The sensitivity was measured at various operating temperatures in the range of 100-400°C. The sensor shows highest sensitivity and selectivity to C{sub 2}H{sub 5}OH at 350°C. The response and recovery time was measured at operating temperature of 350°C. The sensor exhibits a lower response and recovery time for LPG and Cl{sub 2} as compared to ethanol.

  9. Ferrite core coupled slapper detonator apparatus and method

    SciTech Connect

    Boberg, R.E.; Lee, R.S.; Weingart, R.C.

    1989-08-01

    Method and apparatus are provided for coupling a temporally short electric power pulse from a thick flat-conductor power cable into a thin flat-conductor slapper detonator circuit. A first planar and generally circular loop is formed from an end portion of the power cable. A second planar and generally circular loop, of similar diameter, is formed from all or part of the slapper detonator circuit. The two loops are placed together, within a ferrite housing that provides a ferrite path that magnetically couples the two loops. Slapper detonator parts may be incorporated within the ferrite housing. The ferrite housing may be made vacuum and water-tight, with the addition of a hermetic ceramic seal, and provided with an enclosure for protecting the power cable and parts related thereto. 10 figs.

  10. Ferrite core coupled slapper detonator apparatus and method

    DOEpatents

    Boberg, Ralph E.; Lee, Ronald S.; Weingart, Richard C.

    1989-01-01

    Method and apparatus are provided for coupling a temporally short electric power pulse from a thick flat-conductor power cable into a thin flat-conductor slapper detonator circuit. A first planar and generally circular loop is formed from an end portion of the power cable. A second planar and generally circular loop, of similar diameter, is formed from all or part of the slapper detonator circuit. The two loops are placed together, within a ferrite housing that provides a ferrite path that magnetically couples the two loops. Slapper detonator parts may be incorporated within the ferrite housing. The ferrite housing may be made vacuum and water-tight, with the addition of a hermetic ceramic seal, and provided with an enclosure for protecting the power cable and parts related thereto.

  11. Dielectric investigations of polycrystalline samarium bismuth ferrite ceramic

    SciTech Connect

    Palaimiene, E.; Macutkevic, J.; Banys, J.; Karpinsky, D. V.; Kholkin, A. L.

    2015-01-05

    Results of broadband dielectric investigations of samarium doped bismuth ferrite ceramics are presented in wide temperature range (20–800 K). At temperatures higher than 400 K, the dielectric properties of samarium bismuth ferrite ceramics are governed by Maxwell-Wagner relaxation and electrical conductivity. The DC conductivity increases and activation energy decreases with samarium concentration. In samarium doped bismuth ferrite, the ferroelectric phase transition temperature decreases with samarium concentration and finally no ferroelectric order is observed at x = 0.2. At lower temperatures, the dielectric properties of ferroelectric samarium doped bismuth ferrite are governed by ferroelectric domains dynamics. Ceramics with x = 0.2 exhibit the relaxor-like behaviour.

  12. Sustainable synthesis of monodispersed spinel nano-ferrites

    EPA Science Inventory

    A sustainable approach for the synthesis of various monodispersed spinel ferrite nanoparticles has been developed that occurs at water-toluene interface under both conventional and microwave hydrothermal conditions. This general synthesis procedure utilizes readily available and ...

  13. Controlled ferrite content improves weldability of corrosion-resistant steel

    NASA Technical Reports Server (NTRS)

    Malin, C. O.

    1967-01-01

    Corrosion-resistant steel that adds restrictions on chemical composition to ensure sufficient ferrite content decreases the tendency of CRES to develop cracks during welding. The equations restricting composition are based on the Schaeffler constitution diagram.

  14. DARHT-II Injector Transients and the Ferrite Damper

    SciTech Connect

    Waldron, Will; Reginato, Lou; Chow, Ken; Houck, Tim; Henestroza, Enrique; Yu, Simon; Kang, Michael; Briggs, Richard

    2006-08-04

    This report summarizes the transient response of the DARHT-II Injector and the design of the ferrite damper. Initial commissioning of the injector revealed a rise time excited 7.8 MHz oscillation on the diode voltage and stalk current leading to a 7.8 MHz modulation of the beam current, position, and energy. Commissioning also revealed that the use of the crowbar to decrease the voltage fall time excited a spectrum of radio frequency modes which caused concern that there might be significant transient RF electric field stresses imposed on the high voltage column insulators. Based on the experience of damping the induction cell RF modes with ferrite, the concept of a ferrite damper was developed to address the crowbar-excited oscillations as well as the rise-time-excited 7.8 MHz oscillations. After the Project decided to discontinue the use of the crowbar, further development of the concept focused exclusively on damping the oscillations excited by the rise time. The design was completed and the ferrite damper was installed in the DARHT-II Injector in February 2006. The organization of this report is as follows. The suite of injector diagnostics are described in Section 2. The data and modeling of the injector transients excited on the rise-time and also by the crowbar are discussed in Section 3; the objective is a concise summary of the present state of understanding. The design of the ferrite damper, and the small scale circuit simulations used to evaluate the ferrite material options and select the key design parameters like the cross sectional area and the optimum gap width, are presented in Section 4. The details of the mechanical design and the installation of the ferrite damper are covered in Section 5. A brief summary of the performance of the ferrite damper following its installation in the injector is presented in Section 6.

  15. Epitaxial single crystalline ferrite films for high frequency applications

    SciTech Connect

    Suzuki, Y.; Dover, R.B. van; Korenivski, V.; Werder, D.; Chen, C.H.; Felder, R.J.; Phillips, J.M.

    1996-11-01

    The successful growth of single crystal ferrites in thin film form is an important step towards their future incorporation into integrated circuits operating at microwave frequencies. The authors have successfully grown high quality single crystalline spinel ferrite thin films of (Mn,Zn)Fe{sub 2}O{sub 4} and CoFe{sub 2}O{sub 4} on (100) and (110) SrTiO{sub 3} and MgAl{sub 2}O{sub 4} at low temperature. These ferrite films are buffered with spinel structure layers that are paramagnetic at room temperature. In contrast to ferrite films grown directly on the substrates, ferrite films grown on buffered substrates exhibit excellent crystallinity and bulk saturation magnetization values, thus indicating the importance of lattice match and structural similarity between the film and the immediately underlying layer. X-ray, RBS, AFM and TEM analysis provide a consistent picture of the structural properties of these ferrite films. The authors then use this technique to grow exchange-coupled bilayers of single crystalline CoFe{sub 2}O{sub 4} and (Mn,Zn)Fe{sub 2}O{sub 4}. In these bilayers, they observe strong exchange coupling across the interface that is similar in strength to the exchange coupling in the individual layers.

  16. Exchange-spring mechanism of soft and hard ferrite nanocomposites

    SciTech Connect

    Manjura Hoque, S.; Srivastava, C.; Kumar, V.; Venkatesh, N.; Das, H.N.; Saha, D.K.; Chattopadhyay, K.

    2013-08-01

    Graphical abstract: - Highlights: • Exchange-spring behaviour of soft and hard ferrites was studied. • XRD patterns indicated soft and hard ferrites as fcc and hcp structure. • Hysteresis loops indicate wide difference in coercivity of soft and hard phases. • Nanocomposites produced convex hysteresis loop characteristic of single-phase. - Abstract: The paper reports exchange-spring soft and hard ferrite nanocomposites synthesized by chemical co-precipitation with or without the application of ultrasonic vibration. The composites contained BaFe{sub 12}O{sub 19} as the hard phase and CoFe{sub 2}O{sub 4}/MgFe{sub 2}O{sub 4} as the soft phase. X-ray diffraction patterns of the samples in the optimum calcined condition indicated the presence of soft ferrites as face-centred cubic (fcc) and hard ferrites as hexagonal close packed (hcp) structure respectively. Temperature dependence of magnetization in the range of 20–700 °C demonstrated distinct presence of soft and hard ferrites as magnetic phases which are characterized by wide difference in magnetic anisotropy and coercivity. Exchange-spring mechanism led these nanocomposite systems to exchange-coupled, which ultimately produced convex hysteresis loops characteristic of a single-phase permanent magnet. Fairly high value of coercivity and maximum energy product were observed for the samples in the optimum calcined conditions with a maximum applied field of 1600 kA/m (2 T)

  17. Kinetics of Ferrite Recrystallization and Austenite Formation During Intercritical Annealing of the Cold-Rolled Ferrite/Martensite Duplex Structures

    NASA Astrophysics Data System (ADS)

    Mazaheri, Y.; Kermanpur, A.; Najafizadeh, A.; Kalashami, A. Ghatei

    2016-03-01

    Ultrafine-grained, dual-phase (UFG DP) steels were produced by a new route using an uncommon cold-rolling and subsequent intercritical annealing of ferrite/martensite duplex starting microstructures. The effects of processing parameters such as rolling reduction, intercritical annealing temperature, and time on the microstructural evaluations have been studied. UFG DP steels with an average grain size of about 1 to 2 μm were achieved by short intercritical annealing of the 80 pct cold-rolled duplex microstructures. The kinetics of ferrite recrystallization and austenite formation were studied based on the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. The proposed model for describing the isothermal austenite formation kinetics was applied successfully to the nonisothermal conditions. It was found that complete recrystallization of ferrite before the austenite formation led to the formation of a large extent randomly distributed austenite in the ferrite matrix and a chain-networked structure.

  18. Synthesis of Novel Ferrite Based Recyclable Catalyst Used to Clean Dye and Emerging Contaminates from Water

    EPA Science Inventory

    Herein, we describe synthesis of novel palladium, copper, cobalt and vanadium ferrites. The ferrites were synthesized by combustion method using polyvinyl alcohol. The particles phases were confirmed using X-ray diffraction and sizes were determined using particle size analyzer. ...

  19. Performance of ferrite fillers on electrical behavior of polymer nanocomposite electrolyte

    NASA Astrophysics Data System (ADS)

    Pandey, Kamlesh; Mauli Dwivedi, Mrigank; Singh, Markandey; Agrawal, S. L.

    2011-04-01

    Dispersal of nanofillers in polymer electrolytes have shown to improve the ionic properties of Polyethylene oxide (PEO)-based polymer electrolytes in recent times. The effects of different nanoferrite fillers (i.e., Al-Zn ferrite, Mg-Zn ferrite, and Zn ferrite) on the electrical transport properties have been studied here on the composite polymer electrolyte system. The interaction of salt/filler with electrolyte has been investigated by XRD studies. SEM image and infrared spectral studies give an indication of nanocomposite formation. In conductivity studies, all electrolyte systems are seen to follow universal power law. Composition dependence (with ferrite filler) gives the maximum conductivity in [93PEO-7NH4SCN]: X ferrite (where X = 2% in Al-Zn ferrite, 1% Mg-Zn ferrite, and 1% Zn ferrite) system.

  20. A biosensor system using nickel ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Singh, Prachi; Rathore, Deepshikha

    2016-05-01

    NiFe2O4 ferrite nanoparticles were synthesized by chemical co-precipitation method and the structural characteristics were investigated using X-ray diffraction technique, where single cubic phase formation of nanoparticles was confirmed. The average particle size of NiFe2O4 was found to be 4.9 nm. Nanoscale magnetic materials are an important source of labels for biosensing due to their strong magnetic properties which are not found in biological systems. This property of the material was exploited and the fabrication of the NiFe2O4 nanoparticle based biosensor was done in the form of a capacitor system, with NiFe2O4 as the dielectric material. The biosensor system was tested towards different biological materials with the help of electrochemical workstation and the same was analysed through Cole-Cole plot of NiFe2O4. The performance of the sensor was determined based on its sensitivity, response time and recovery time.