WorldWideScience

Sample records for octupole deformation properties

  1. Collective properties of octupole-deformed atomic nuclei

    Collective properties of even-even nuclei in the radium region are studied theoretically. Energy of the lowest collective states and reduced probabilities B(E2) and B(E3) of electromagnetic transitions between these states are mainly analysed. The excited states are treated as large-amplitude quadrupole and octupole vibrations coupled with each other. A large anharmonicity of the spectrum and a large value B(E3) of the transition from the first octupole excited state to the ground state are obtained, for octupole-deformed nuclei. A strong dependence of the results on the shape of the potential energy of a nucleus, treated as a function of its deformation, is stressed. (author)

  2. Rotations of Nuclei with Octupole Deformations

    We study collective interactions capable to generate rotations in nuclei with a simultaneous presence of octupole and quadrupole deformations. On this basis we propose a collective Hamiltonian which incorporates the standard quadrupole terms, octupole terms classified according to the irreducible representations of the octahedron point symmetry group, a quadrupole-octupole interaction, as well as a term for the band-head energy linear in K (the projection of angular momentum on the body-fixed z-axis). The energy is subsequently minimised with respect to K for each given value of the angular momentum I, resulting in K values increasing with I within each band. We demonstrate that this Hamiltonian is able to reproduce a variety of 'beat' patterns observed recently for the odd-even staggering in octupole bands of light actinides. In addition, we suppose that the model can be applied to reproduce the staggering effects in rotational negative parity bands built on octupole vibrations. On the above basis we expect that the interactions involved would provide a relevant handle in the study of collective phenomena in nuclei and other quantum mechanical systems with a presence of octupole degrees of freedom. (authors)

  3. Octupole Deformed Nuclei in the Actinide Region

    Thorsteinsen, T; Rubio barroso, B; Simpson, J; Gulda, K; Sanchez-vega, M; Cocks, J; Nybo, K; Garcia borge, M; Aas, A; Fogelberg, B; Honsi, J; Smith, G; Naumann, R; Grant, I

    2002-01-01

    The aim of the present study is to investigate the limits of the "island" of octupole deformation in the mass region A=225. It is of particular importance to demonstrate experimentally the sudden disappearance of the stable octupole deformation in the presence of a well developed quadrupole field. \\\\ \\\\In order to establish the upper border line the $\\beta$ -decay chains of $^{227}$Rn $\\rightarrow ^{227}$Fr $\\rightarrow ^{227}$Ra and $^{231}$Fr $\\rightarrow ^{231}$Ra $\\rightarrow ^{231}$Ac were studied at PSB-ISOLDE using advanced fast timing and $\\gamma$-ray spectroscopy techniques. The lifetimes of the excited states have been measured in the picosecond range using the time-delayed $\\beta\\gamma\\gamma$(t) method.

  4. Search for octupole deformation in neutron-rich Xe isotopes

    A search for octupole deformation in neutron-rich Xe isotopes has been conducted by prompt gamma-ray spectroscopy of secondary fragments produced in the spontaneous fission of 248Cm. The spectrometer consisted of the Eurogam 1 array and a set of 5 LEPS detectors. Level schemes were constructed for Xe isotopes with mass number ranging from 140 to 144 and excited states for 143,144Xe nuclei were observed for the first time. None of the level schemes exhibit an alternating parity quasimolecular band, a feature usually expected in nuclei in which octupole correlation effects are strong enough to produce stable octupole deformation. For several isotopes, structures observed in the level schemes are consistent with an octupole softness of the nuclei. (orig.)

  5. Search for octupole deformation in neutron rich Xe isotopes

    A search for octupole deformation in neutron rich Xe isotopes has been conducted through gamma-ray spectroscopy of primary fragments produced in the spontaneous fission of 248Cm. The spectrometer consisted of the Eurogam array and a set of 5 LEPS detectors. Level schemes were constructed for Xe isotopes with masses ranging from 138 to 144. Except for 139Xe, none of them exhibit an alternating parity quasimolecular band, α feature usually encountered in octupole deformed nuclei. Substantial evidence for reflection asymmetric shape in the intrinsic system of the nucleus exists for the light actinide nuclei

  6. Search for octupole deformation in neutron rich Xe isotopes

    Bentaleb, M.; Schulz, N.; Lubkiewicz, E. [Universite Louis Pasteur, Strasbourg (France). Centre de Recherches Nucleaires] [and others

    1994-07-01

    A search for octupole deformation in neutron rich Xe isotopes has been conducted through gamma-ray spectroscopy of primary fragments produced in the spontaneous fission of {sup 248}Cm. The spectrometer consisted of the Eurogam array and a set of 5 LEPS detectors. Level schemes were constructed for Xe isotopes with masses ranging from 138 to 144. Except for {sup 139}Xe, none of them exhibit an alternating parity quasimolecular band, {alpha} feature usually encountered in octupole deformed nuclei. Substantial evidence for reflection asymmetric shape in the intrinsic system of the nucleus exists for the light actinide nuclei.

  7. Collective motion of a pure octupole deformed system

    The collective motion of a pure octupole deformed system is treated as the vibrations in body-fixed frame and rotation of this system about the axes of lab-system, as well as the coupling between vibrations and rotation. The quantized operator of kinetic energy is derived and the collective spectra built on some special equilibrium shapes are discussed

  8. Quadrupole-octupole deformation in finite fermion system

    Using a two-level model as well as a modified oscillator model, which simulates the one-particle spectra in an infinite-well potential, we study the most favourable shape of octupole deformation superposed on quadrupole deformation. The importance of the non-axially-symmetric Y33 deformation, which is superposed on prolate or oblate deformation depending on the degree of the shell-filling, is pointed out. In the middle of the major shell almost pure Y32 deformation is found to be energetically most favourable. (orig.)

  9. Studies of Stable Octupole Deformations in the Radium Region

    2002-01-01

    The purpose of the present project is to locate and identify states in the atomic nuclei possessing stable pearshaped octupole deformation. Such states, formally related to the structures known in molecular physics, manifest themselves as families of parity doublets in odd nuclei.\\\\ \\\\ The best possibilities for observing stable octupole deformations are offered in the Ra-region. Both theoretical calculations and experimental indications support such expectations. Such indications are the non-observation of two-phonon octupole vibrational states in the ISOLDE studies of the even-even radium nuclei, and the reversed sign of the decoupling factor of the ground state band in |2|2|5Ra observed in the single-neutron transfer reactions. In order to establish the predicted strong E1 and E3-transitions between the parity doublets in odd nuclei with stable octupole deformations it is proposed to study conversion electrons in odd-mass francium radium and radon isotopes following the @b-decay of francium and astatine. \\...

  10. Influence of the octupole mode on nuclear high-K isomeric properties

    Minkov, Nikolay; Walker, Phil

    2014-05-01

    The influence of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even actinide (U, Pu, Cm, Fm, No), rare-earth (Nd, Sm and Gd), and superheavy (^{270}\\text{Ds}) nuclei is examined within a deformed shell model with pairing interaction. The neutron two-quasiparticle (2qp) isomeric energies and magnetic dipole moments are calculated over a wide range in the plane of quadrupole and octupole deformations. In most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation. At the same time, the calculations outline three different groups of nuclei: with pronounced, shallow, and missing minima in the 2qp energy surfaces with respect to the octupole deformation. The result indicates regions of nuclei with octupole softness as well as with possible octupole deformation in the high-K isomeric states. These findings show the need for further theoretical analysis as well as of detailed experimental measurements of magnetic moments in heavy deformed nuclei.

  11. Influence of the octupole mode on nuclear high-K isomeric properties

    The influence of quadrupole–octupole deformations on the energy and magnetic properties of high-K isomeric states in even–even actinide (U, Pu, Cm, Fm, No), rare-earth (Nd, Sm and Gd), and superheavy (270Ds) nuclei is examined within a deformed shell model with pairing interaction. The neutron two-quasiparticle (2qp) isomeric energies and magnetic dipole moments are calculated over a wide range in the plane of quadrupole and octupole deformations. In most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation. At the same time, the calculations outline three different groups of nuclei: with pronounced, shallow, and missing minima in the 2qp energy surfaces with respect to the octupole deformation. The result indicates regions of nuclei with octupole softness as well as with possible octupole deformation in the high-K isomeric states. These findings show the need for further theoretical analysis as well as of detailed experimental measurements of magnetic moments in heavy deformed nuclei

  12. Further confirmation of octupole deformation in ^144Ba

    Yzaguirre, W. A.; Hamilton, J. H.; Liu, S. H.; Ramayya, A. V.; Hwang, J. K.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.

    2009-11-01

    The energy levels in ^144Ba have been studied with our high statistics 5.7 x10^11 triple- and higher- fold coincidence data taken with Gammasphere. There are reinforcing shell gaps for ?2= 0.13 for Z=56 and Z=88, so octupole deformation is expected in ^144Ba. The even parity ground state band is seen to high spin with crossing E1 transitions from an odd spin, negative parity band earlier, the expected si=1 band. Limited evidence for the expected si=-1 band with the same spins and opposite parities has been reported. si=-1 band has been clearly established now with the expected crossing transitions between the even and odd spins members. In addition, numbers of new crossing transitions in the si=1 band and between the si=-1 band and +1 are seen. These data firmly established the octupole deformation of ^144Ba. Work supported by the U.S. Department of Energy under Grants and Contract Nos. DE-FG05-88ER40407 and DE-AC03- 76SF00098.

  13. Microscopic and semi-classical treatments of octupole deformation in the light actinides

    Microscopic and semi-classical descriptions of octupole deformation are compared. New semi-classical results, obtained with the use of a Woods-Saxon potential are presented. Comparisons with experiment are made. 21 references

  14. Effect of the coriolis and centrifugal forces for nuclei with a stable octupole deformation

    Effects of the Coriolis and centrifugal forces for nuclei with a stable octupole deformation are examined in the frame of a schematic collective model. It is found that these effects are by no means attenuated with a rise of the octupole deformation. Taking them into account seems to allow for a consistent description of a strong anharmonization and differences in the moments of inertia of the positive- and negative-parity bands. (orig.)

  15. Collective models for quadrupole and octupole degrees of freedom and complex nuclear deformations

    We review current advances in the theoretical study of nuclear quadrupole and octupole collectivity and complex shape deformations. We present a collective model formalism which consistently describes the strong parity shift effect observed in low-lying spectra of nuclei with octupole deformations together with the fine rotational band structure developed at higher angular momenta. The parity effect is obtained by the Schroedinger equation for oscillations of the reflection asymmetric (octupole) shape between two opposite orientations in an angular momentum dependent double-well potential. The rotational structure is obtained by the collective quadrupole-octupole rotation Hamiltonian (QORM). The unified model scheme reproduces the complicated beat staggering patterns observed in the octupole bands of light actinide nuclei. It explains the angular momentum evolution of octupole spectra as the interplay between the octupole shape oscillation (parity shift) mode and the stable quadrupole-octupole rotation mode. We also discuss an analytic collective model in which the relative presence of the quadrupole and octupole deformations is determined by a parameter (ψ0), while axial symmetry is obeyed. The model, called the Analytic Quadrupole Octupole Axially Symmetric model (AQOA), involves an infinite well potential, provides predictions for energy and B(EL) ratios which depend only on (ψ0), draws the border between the regions of octupole deformation and octupole vibrations in an essentially parameter-independent way, and describes well 226Th and 226Ra, for which experimental energy data are shown to suggest that they lie close to this border. The similarity of the AQOA results with ψ0=450 for ground state band spectra and B(E2) transition rates to the predictions of the X(5) model is pointed out. Analytic solutions are also obtained for Davidson potentials of the form β2+β4/β2, leading to the AQOA spectrum through a variational procedure. Also, we present results of a recent model study of the rotation-vibration motion of nuclei in which the axial quadrupole and octupole degrees of freedom are coupled through the centrifugal interaction. The collective potential depends on the two deformation variables β2 and β3 as well as on the angular momentum. In the limit of a frozen β2 the system oscillates between positive and negative octupole deformations by tunnelling through the barrier of the double-well potential in β3. When β2 is let to vary, the system oscillates between the positive and negative β3-values by rounding the barrier in the (β2, β3 )- plane, instead of tunnelling. We examine the consequence of the 'rounding' in the cases when: i) the potential minima increase with the angular momentum I, and ii) the minima do not change with I. In the first case the spectrum of the system is characterized by a parity shift effect which decreases with the increase of I, while in the second case a constant parity shift is obtained. This result outlines a general framework for the evolution of nuclear collectivity in the regions where octupole vibrations and octupole deformations are observed

  16. Octupole deformation and Ra puzzle in reflection asymmetric covariant density functional theory

    Yu, L F; Zhang, S Q; Meng, J

    2012-01-01

    Reflection asymmetric covariant density functional theory(CDFT) based on the point-coupling interaction is established on a two-center harmonic-oscillator basis and applied to investigate the Ra puzzle, i.e., the anomalous enhancement of the residual proton-neutron interactions for Ra isotopes around N=135. The octupole deformation and shape evolution in the Ra and Rn isotopes are examined in the potential energy surfaces in(beta2, beta3) plane by the constrained reflection asymmetric calculations. The residual proton-neutron interactions extracted from the double difference of the binding energies for Ra isotopes are compared with the data as well as the axial and the triaxial calculations. It is found that the octupole deformation is responsible for the Ra puzzle in the microscopic CDFT.

  17. Exotic octupole deformation in proton-rich Z=N nuclei

    Takami, Satoshi; Yabana, K. [Niigata Univ. (Japan); Matsuo, M.

    1998-03-01

    We study static non-axial octupole deformations in proton-rich Z=N nuclei, {sup 64}Ge, {sup 68}Se, {sup 72}Kr, {sup 76}Sr, {sup 80}Zr and {sup 84}Mo, by using the Skyrme Hartree-Fock plus BCS method with no restrictions on the nuclear shape. The calculation predicts that the oblate ground state in {sup 68}Se is extremely soft for the Y{sub 33} triangular deformation, and that in {sup 80}Zr the low-lying local minimum state coexisting with the prolate ground state has the Y{sub 32} tetrahedral deformation. (author)

  18. Direct Evidence of Octupole Deformation in Neutron-Rich $^{144}$Ba

    Bucher, B; Wu, C Y; Janssens, R V F; Cline, D; Hayes, A B; Albers, M; Ayangeakaa, A D; Butler, P A; Campbell, C M; Carpenter, M P; Chiara, C J; Clark, J A; Crawford, H L; Cromaz, M; David, H M; Dickerson, C; Gregor, E T; Harker, J; Hoffman, C R; Kay, B P; Kondev, F G; Korichi, A; Lauritsen, T; Macchiavelli, A O; Pardo, R C; Richard, A; Riley, M A; Savard, G; Scheck, M; Seweryniak, D; Smith, M K; Vondrasek, R; Wiens, A

    2016-01-01

    The neutron-rich nucleus $^{144}$Ba ($t_{1/2}$=11.5 s) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers $A$ less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced $E1$ transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multi-step Coulomb excitation of a post-accelerated 650-MeV $^{144}$Ba beam on a 1.0-mg/cm$^2$ $^{208}$Pb target. The measured value of the matrix element, $\\langle 3_1^- \\| \\mathcal{M}(E3) \\| 0_1^+ \\rangle=0.65(^{+17}_{-23})$ $e$b$^{3/2}$, corresponds to a reduced $B(E3)$ transition probability of 48($^{+25}_{-34}$) W.u. This result represents an unambiguous determination of the octupole collectivity, is larger than any available theoretical prediction, and is consistent with octupole deformation.

  19. Octupole deformation in the ground states of even-even nuclei: A global analysis within the covariant density functional theory

    Agbemava, S. E.; Afanasjev, A. V.; Ring, P.

    2016-04-01

    A systematic investigation of octupole-deformed nuclei is presented for even-even systems with Z ≤106 located between the two-proton and two-neutron driplines. For this study we use five most-up-to-date covariant energy density functionals of different types, with a nonlinear meson coupling, with density-dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov theory based on an effective separable particle-particle interaction of finite range. This allows us to assess theoretical uncertainties within the present covariant models for the prediction of physical observables relevant for octupole-deformed nuclei. In addition, a detailed comparison with the predictions of nonrelativistic models is performed. A new region of octupole deformation, centered around Z ˜98 ,N ˜196 is predicted for the first time. In terms of its size in the (Z ,N ) plane and the impact of octupole deformation on binding energies this region is similar to the best known region of octupole-deformed nuclei centered at Z ˜90 ,N ˜136 . For the later island of octupole-deformed nuclei, the calculations suggest substantial increase of its size as compared with available experimental data.

  20. Accuracy of the multipole expansion of density distribution in the presence of octupole deformation

    The accuracy of multipole expansion of density distribution for deformed nuclei is tested. The interaction potential for a deformed-spherical pair of nuclei was calculated using the folding model derived from zero-range nucleonnucleon (NN) interaction. We considered two spherical projectiles Ca40 and Pb208 scattered on U238 deformed target nucleus. The error in the heavy ion (HI) potential resulting from using a truncated multipole density expansion is evaluated for each case in the presence of octupole deformation ?3 besides quadrupole ?2. We are interested in the value of error for R ? RT (touching distance). We found that for values of |?3|?0.1 the error at R = RT reaches reasonable values when six terms expansion is used. For |?3| = 0.2, we calculated the Coulomb barrier parameters using realistic NN force and found that the large error present in six terms for zero range force decreases strongly to less than 1% when the zero range is added to finite range forces and Coulomb interaction to form the Coulomb barrier. It is noted that the negative value of octupole deformation parameters ?3 = -0.1 produce error at orientation angle ? equal in value to that produced at angle (180-?) for the positive values ?3 = 0.1. We also found that the error decreases as the mass number of the projectile nucleus increases. (author)

  1. Octupole deformation in the ground states of even-even nuclei: a global analysis within the covariant density functional theory

    Agbemava, S E; Ring, P

    2016-01-01

    A systematic investigation of octupole deformed nuclei is presented for even-even systems with $Z\\leq 106$ located between the two-proton and two-neutron drip lines. For this study we use five most up-to-date covariant energy density functionals of different types, with a non-linear meson coupling, with density dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov (RHB) theory based on an effective separable particle-particle interaction of finite range. This allows us to assess theoretical uncertainties within the present covariant models for the prediction of physical observables relevant for octupole deformed nuclei. In addition, a detailed comparison with the predictions of non-relativistic models is performed. A new region of octupole deformation, centered around $Z\\sim 98, N\\sim 196$ is predicted for the first time. In terms of its size in the $(Z,N)$ plane and the impact of octupole deformation on binding e...

  2. Study of octupole deformation in n-rich Ba isotopes populated via $\\beta$-decay

    We propose to exploit the unique capability of the ISOLDE facility to produce $^{150−151−152}$Cs beams to investigate their radioactive $\\beta$-decay to $^{150−151−152}$Ba. The interest to study this mass region is twofold: from one side these nuclei are expected to show octupole deformations already in their low-lying state, and, on the other hand, gross information on the $\\beta$-decay is highly demanded for nuclear astrophysical model, given the fact that the r-process path lies in the proximity of 1 accessible nuclei. The experiment will be performed with the ISOLDE Decay Station (IDS) setup using the fast tape station of K.U.-Leuven, equipped with 4 Clover Germanium detectors, 4 LaBr$_{3}$(Ce) detectors and 1 LEP HPGe detector. Information on the $\\beta$-decay, such as lifetimes and delayed neutron-emission probabilities, will be extracted, together with the detailed spectroscopy of the daughter nuclei, via $\\gamma$ - $\\gamma$- coincidences and lifetimes measurement of specific states.

  3. Octupole shapes in heavy nuclei

    Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets

  4. Octupole shapes in heavy nuclei

    Ahmad, I.

    1994-08-01

    Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets.

  5. Observation of K=1/2 octupole deformed bands in 227Th

    High-spin states in 227Th have been populated using the reaction 226Ra(?,3n)227Th at a bombarding energy of 33 MeV. The high-spin rotational structures of this nucleus have been refined and extended. In addition, the linking of these structures with the low-spin states known from 231U ? decay has allowed a comprehensive decay scheme of this nucleus to be assembled for the first time. Four previously known rotational bands are interpreted as Coriolis coupled K?=1/2+ and K?=1/2- bands, in agreement with predictions using a reflection-asymmetric mean field approach. The determination of decoupling parameters for these bands is consistent with the a(K?=1/2+)=-a(K?=1/2-) rigid octupole rotor expectation. A further rotational band is interpreted as having K?=3/2-. Measured D0/Q0 ratios are consistent with an interpolation of the values given for neighboring even-even nuclei, providing further evidence for the significance of strong octupole correlations in this nucleus

  6. Octupole effects in the lanthanides

    Arrays of Anti-Compton Spectrometer enabled systematic investigations of octupole correlations in the neutron-rich lanthanides. The studies mostly confirm the theoretical expectations of moderate octupole deformation at medium spins in nuclei from this region but in some cases predictions deviate from the experiment. In cesium isotopes strong octupole effects are predicted but not observed and new measurements for 139Xe suggest octupole effects stronger than expected. Systematics of excitation energy of the 31 states excitations, updated in the present work for Xe isotopes, indicates the N=85 and Z=54 lines as borders for strong octupole correlations. Systematic of electric dipole moment, upgraded in the present work for Ca and Ce isotopes confirms the Z=54 limit and adds new information about local canceling of electric dipole moment at the N=90 neutron number

  7. Octupole effects in the lanthanides

    Urban, W.; Rzaca-Urban, T.; Phillips, W. R.; Durell, J. L.; Leddy, M. J.; Smith, A. G.; Varley, B. J.; Schulz, N.; Bentaleb, M.; Lubkiewicz, E.; Ahmad, I.; Morss, L. R.

    1999-10-22

    Arrays of Anti-Compton Spectrometer enabled systematic investigations of octupole correlations in the neutron-rich lanthanides. The studies mostly confirm the theoretical expectations of moderate octupole deformation at medium spins in nuclei from this region but in some cases predictions deviate from the experiment. In cesium isotopes strong octupole effects are predicted but not observed and new measurements for {sup 139}Xe suggest octupole effects stronger than expected. Systematics of excitation energy of the 31 states excitations, updated in the present work for Xe isotopes, indicates the N=85 and Z=54 lines as borders for strong octupole correlations. Systematic of electric dipole moment, upgraded in the present work for Ca and Ce isotopes confirms the Z=54 limit and adds new information about local canceling of electric dipole moment at the N=90 neutron number.

  8. Microscopic analysis of the octupole phase transition in Th isotopes

    Nomura, K; Lu, B -N

    2013-01-01

    A shape phase transition between stable octupole deformation and octupole vibrations in Th nuclei is analyzed in a microscopic framework based on nuclear density functional theory. The relativistic functional DD-PC1 is used to calculate axially-symmetric quadrupole-octupole constrained energy surfaces. Observables related to order parameters are computed using an interacting-boson Hamiltonian, with parameters determined by mapping the microscopic energy surfaces to the expectation value of the Hamiltonian in the boson condensate. The systematics of constrained energy surfaces and low-energy excitation spectra point to the occurrence of a phase transition between octupole-deformed shapes and shapes characterized by octupole-soft potentials.

  9. Test of the transport properties of a helical electrostatic quadrupole and quasi-octupole

    A third-generation continuous helical electrostatic quadrupole (HESQ) lens has been built and tested. The new HESQ is 21.5 cm long and has a 3.6 cm diameter aperture. The HESQ has been tested under two separate conditions: with a pulsed 25 keV, 0.5 mA proton beam; and a 25 keV, 10 mA proton beam. The input emittance was fixed using a multi-aperture collimator. A comparison is made between experiment and numerical simulations for a wide variety of operating conditions. A second possible operating mode is the quasi-octupole mode, which offers significantly reduced aberration when compared to the quadrupole mode. The results of preliminary tests in this operating mode will be presented

  10. Octupole collectivity in the Sm isotopes

    Microscopic models suggest the occurrence of strong octupole correlations in nuclei with N≅88. To examine the signatures of octupole correlations in this region, the spdf interacting boson approximation model is applied to Sm isotopes with N=86-92. The effects of including multiple negative-parity bosons in this basis are compared with more standard one negative-parity boson calculations and are analyzed in terms of signatures for strong octupole correlations. It is found that multiple negative-parity bosons are needed to describe properties at medium spin. Bands with strong octupole correlations (multiple negative-parity bosons) become yrast at medium spin in 148,150Sm. This region shares some similarities with the light actinides, where strong octupole correlations were also found at medium spin

  11. Nonaxial-octupole effect in superheavy nuclei

    Chen, Y.-S.; Sun, Yang; Gao, Zao-Chun

    2008-06-01

    The triaxial-octupole Y32 correlation in atomic nuclei has long been expected to exist but experimental evidence has not been clear. We find, in order to explain the very low-lying 2- bands in the transfermium mass region, that this exotic effect may manifest itself in superheavy elements. Favorable conditions for producing triaxial-octupole correlations are shown to be present in the deformed single-particle spectrum, which is further supported by quantitative Reflection Asymmetric Shell Model calculations. It is predicted that the strong nonaxial-octupole effect may persist up to the element 108. Our result thus represents the first concrete example of spontaneous breaking of both axial and reflection symmetries in the heaviest nuclear systems.

  12. Nonaxial-octupole effect in superheavy nuclei

    Chen, Y -S; Gao, Zao-Chun

    2008-01-01

    The triaxial-octupole Y$_{32}$ correlation in atomic nuclei has long been expected to exist but experimental evidence has not been clear. We find, in order to explain the very low-lying 2$^-$ bands in the transfermium mass region, that this exotic effect may manifest itself in superheavy elements. Favorable conditions for producing triaxial-octupole correlations are shown to be present in the deformed single-particle spectrum, which is further supported by quantitative Reflection Asymmetric Shell Model calculations. It is predicted that the strong nonaxial-octupole effect may persist up to the element 108. Our result thus represents the first concrete example of spontaneous breaking of both axial and reflection symmetries in the heaviest nuclear systems.

  13. Microscopic analysis of quadrupole-octupole shape evolution

    Nomura Kosuke

    2015-01-01

    Full Text Available We analyze the quadrupole-octupole collective states based on the microscopic energy density functional framework. By mapping the deformation constrained self-consistent axially symmetric mean-field energy surfaces onto the equivalent Hamiltonian of the sdf interacting boson model (IBM, that is, onto the energy expectation value in the boson coherent state, the Hamiltonian parameters are determined. The resulting IBM Hamiltonian is used to calculate excitation spectra and transition rates for the positive- and negative-parity collective states in large sets of nuclei characteristic for octupole deformation and collectivity. Consistently with the empirical trend, the microscopic calculation based on the systematics of β2 – β3 energy maps, the resulting low-lying negative-parity bands and transition rates show evidence of a shape transition between stable octupole deformation and octupole vibrations characteristic for β3-soft potentials.

  14. Energy levels and reduced probabilities of electric dipole, quadrupole and octupole transitions of 226Ra

    The energy levels and reduced probabilities of electric dipole, quadrupole and octupole transitions measured in the Coulomb excitation of 226Ra are analyzed in the framework of the soft axial-symmetric rotator model with quadrupole and octupole deformations. The calculated values are in good agreement with experimental data. (author). 11 refs., 2 figs

  15. Improvements on the present theoretical understanding of octupole correlations

    Robledo L.M.

    2014-03-01

    Full Text Available Some intriguing results, obtained in a recent survey of octupole properties for all even-even nuclei, are reanalyzed in order to understand the origin of the strong disagreement with experimental data and/or the strange behaviours observed. The limitations of the rotational formula to describe E1 and E3 transition strengths are discussed as well as the role played by octupole-quadrupole coupling in some specific nuclei.

  16. Petrophysical Properties of Deformed Sandstone Reservoir

    2012-01-01

    Small scale deformation structures that mostly occur in highly porous rocks are called deformation bands. Petrophysical characteristics of deformation bands are different from those of host rock and they can act as barriers or conduit to fluid flow. The effect on fluid flow is the most important property of these structures which is essential in many geological fields; for instance oil & gas, CO2 storage and ground water flow, when permeability and capillary pressure are the tw...

  17. Uniform beam distributions using octupoles

    The Gaussian beam profile of the BNL 200 MeV H- Linac beam at the Radiation Effects Facility target location was transformed into a rectangular profile with almost uniform distribution by placing two octupole magnetic elements at particular locations along the beam line. Experimental results of the beam profile projection in the horizontal and vertical planes, with and without octupoles, are presented and compared with third order calculations. 7 refs., 3 figs

  18. Octupole vibrational states in the lead region

    Collective properties of 206Pb, 207Pb, 208Pb and 209Bi have been investigated with gamma-ray spectroscopy using electromagnetic excitation by 208Pb projectiles. By measuring the absolute yields of the de-excitation γ-rays, B(E3) values for the 1-phonon octupole vibrational states were obtained. While the present data for 208Pb and 209Bi are consistent with earlier publications, much smaller values have been found for 206Pb abd 207Pb. Only for the doubly magic nucleus 208Pb one observes the largest octupole collectivity of 34 Weisskopf units (W.u.), which is reduced to 60-70% by the particle-vibration coupling in nuclei which consist of the 208Pb core plus (or minus) a few nucleons. As a consequence of the phonon vibration character of the 3- state, one expects a quadruplet of 2-phonon octupole states with spins and parities 0+, 2+, 4+ and 6+ at about twice the energy of the 1-phonon state. A first scattering experiment suggesting the observation of at least one member of the 2-phonon multiplet was performed via the reaction 208Pb+208Pb at an incident energy well above the Coulomb barrier. In the present experiment the system 208Pb+208Pb has been reinvestigated via Coulomb excitation at a safe bombarding energy at 5.0 MeV/u. The reduced cross-section for the excitation of the octupole states has been compensated by the higher full energy efficiency of five EUROBALL CLUSTER detectors. With the present experimental set-up transition probabilities down to 10-5-10-6 can be measured

  19. Non-yrast quadrupole-octupole spectra

    Lenske H.

    2012-12-01

    Full Text Available A model of strongly coupled quadrupole and octupole vibrations and rotations is applied to describe non-yrast alternating-parity sequences in even-even nuclei and split parity-doublet spectra in odd-mass nuclei. In even-even nuclei the yrast alternating-parity sequence includes the ground-state band and the lowest negative-parity levels with odd angular momenta, while the non-yrast sequences include excited β-bands and higher negative-parity levels. In odd-mass nuclei the yrast levels are described as low-energy rotation-vibration modes coupled to the ground single-particle (s.p. state, while the non-yrast parity-doublets are obtained as higher-energy rotation-vibration modes coupled to excited s.p. configurations. We show that the extended model scheme describes the yrast and non-yrast quadrupole-octupole spectra in both even-even and odd-A nuclei. The involvement of the reflection-asymmetric deformed shell model to explain the single-particle motion and the Coriolis interaction in odd nuclei is discussed.

  20. Toroidal discharges in an octupole field

    Experimental results from the Extrap T1 device are reported. The Extrap T1 machine has a toroidal stainless steel below vessel, R/a=0.5/0.06 m, covered with a segmented shell. A special character of the device is a coil system which produces an octupole magnetic field. The application of the octupole field produce an equilibrium with four poloidal field nulls. Three modes of operation are considered; 1) toroidal field only, 2) toroidal field and octupole field, 3) octupole field only. The purpose of the present experiment was to study the effect of the octupole field. (author) 4 refs., 5 figs

  1. Quadrupole-octupole electromagnetic lens

    Paper introduces a simplified structure of an achromatic quadrupole lens with spherical aberration correction. Electrodes of a quadrupole-octupole lens are made in the form of a cylinder slitted along the constituents into eight sections with similar angular dimensions. In this case, four electrodes placed between the quadrupole electrodes serve as pole pieces of a magnetic lens

  2. The octupoles take pole position

    2002-01-01

    The first preseries octupole magnet was delivered to CERN in December 2001. Hooked up to a main quadrupole magnet, its function will be to correct imperfections in the beams. The LHC will be fitted with about 5000 corrector magnets, whose task it will be to provide maximum precision in beam collisions.

  3. Octupole correlations in low-lying states of 150Nd and 150Sm and their impact on neutrinoless double-beta decay

    Yao, J M

    2016-01-01

    We present a generator-coordinate calculation, based on a relativistic energy-density functional, of the low-lying spectra in the isotopes $^{150}$Nd and $^{150}$Sm and of the nuclear matrix element that governs the neutrinoless double-beta decay of the first isotope to the second. We carefully examine the impact of octupole correlations on both nuclear structure and the double-beta decay matrix element. Octupole correlations turn out to reduce quadrupole collectivity in both nuclei. Shape fluctuations, however, dilute the effects of octupole deformation on the double-beta decay matrix element, so that the overall octupole-induced quenching is only about 7\\%.

  4. Studies of electric dipole moments in the octupole collective regions of heavy Radiums and Bariums

    Hoff, P; Kaczarowski, R

    2002-01-01

    %IS386 %title\\ \\It is proposed to study the electric dipole moments in the regions of octupole collective Ra-Th and Ba-Ce nuclei by means of Advanced Time-Delayed (ATD) $\\beta\\gamma\\gamma(t)$ method with a primary goal to provide new and critical data on the properties of E1 moments. The proposal focuses on the nuclei of $^{225,226,229}$Ra, $^{229,233}$Th and $^{149,150}$Ba.\\ \\The ATD $\\beta\\gamma\\gamma$(t) method was first tested at ISOLDE as part of the IS322 study of Fr-Ra nuclei at the limits of octupole deformation region. The results have greatly increased the knowledge of electric dipole moments in the region and demonstrated that new and unique research capabilities in this field are now available at ISOLDE. Based on the experience and new systematics, we propose a specialized study with the aim to determine the missing key aspects of the E1 moment systematics. We propose : \\begin{enumerate}[a)] \\item to measure the lifetimes of the 1$_{1}^{-}$ and 3$_{1}^{-}$ states in $^{226}$Ra with $\\sim$15\\% prec...

  5. Deformation Properties and Fatigue of Bituminous Mixtures

    Frantisek Schlosser; Jan Mikolaj; Viera Zatkalikova; Juraj Sramek; Dominika Durekova; Lubos Remek

    2013-01-01

    Deformation properties and fatigue performance are important characteristics of asphalt bound materials which are used for construction of pavement layers. Viscoelastic asphalt mixtures are better characterized via dynamic tests. This type of tests allows us to collate materials with regard to axle vibrations which lie usually in the range of 6 Hz–25 Hz for standard conditions. Asphalt modified for heat sensitivity in the range from −20°C to +60°C has significant impact on the overall charact...

  6. The properties of Q-deformed hyperbolic and trigonometric functions in quantum deformation

    Quantum deformation has been studied due to its relation with applications in nuclear physics, conformal field theory, and statistical-quantum theory. The q-deformation of hyperbolic function was introduced by Arai. The application of q-deformed functions has been widely used in quantum mechanics. The properties of this two kinds of system explained in this paper including their derivative. The graph of q-deformed functions presented using Matlab. The special case is given for modified Poschl-Teller plus q-deformed Scarf II trigonometry potentials

  7. The properties of Q-deformed hyperbolic and trigonometric functions in quantum deformation

    Deta, U. A.; Suparmi

    2015-09-01

    Quantum deformation has been studied due to its relation with applications in nuclear physics, conformal field theory, and statistical-quantum theory. The q-deformation of hyperbolic function was introduced by Arai. The application of q-deformed functions has been widely used in quantum mechanics. The properties of this two kinds of system explained in this paper including their derivative. The graph of q-deformed functions presented using Matlab. The special case is given for modified Poschl-Teller plus q-deformed Scarf II trigonometry potentials.

  8. Deformation properties of thin polymer films

    Dion, John Bernard

    Thin polymer films being processed mostly on rigid substrates experience a "self-orientation" tendency toward a preferred planar orientation of the main-chain of the polymer backbone parallel to the in-plane direction of the film. This tendency increases as the length (called the Kuhn length) between the natural hinges of the polymer increases. The orientation causes the thermoelastic properties of the films to vary from the in-plane direction to the out-of-plane direction. Experimental methods are developed to measure the out-of-plane displacement of polymer films, 10-100 mum thick. The films are adhered to rigid substrates and experience thermal and mechanical displacements in the out-of-plane direction. These displacements are influenced by the constraining effect of the substrates which acts within the plane of the film. Thus, the constraining effect is analyzed in order to separate the true properties of elastic modulus and coefficient of thermal expansion from the as-measured or apparent properties. This analysis also required the knowledge of the in-plane and out-of-plane Poisson's ratio. Techniques are developed to measure these ratios which are also dependent on anisotropy in structure. The anisotropic thermomechanical properties of thin films processed on substrates are found to vary by a factor of 2-10, as compared to the in-plane (or isotropic) values for the polyimides PMDA//PDA and BPDA//PDA and epoxy based adhesives. Under an increase in displacement, the elastic response will eventually suffer an increasing amount of inelastic deformation. This non-elastic deformation has also been investigated based on the relaxation of a stress applied to epoxy based adhesive films sandwiched between two rigid substrates. The amount of stress relaxation decreases as the thickness of the epoxy based adhesive films is decreased, due to a hydrostatic state of stress associated with the presence of an in-plane residual stress which occurs during the thermal curing of the film on the rigid substrates and additional in-plane stress produced by substrate constraint.

  9. Optical properties of plastically deformed copper : #an #ellipsometric study

    Rom?evi?, Neboja; Rudolf, Rebeka; Traji?, J.; Rom?evi?, M.; Hadi?, B.; Vasiljevi?-Radovi?, Dana; Anel, Ivan

    2012-01-01

    In this paper the results of optical properties investigations on plastically deformed copper are presented. The optical properties of the plastically deformed copper were studied using spectroscopic ellipsometry in the ultraviolet-visible (UV-VIS) range. Chemically pure copper was deformed by applying the Equal Channel Angular Pressing (ECAP) technique. During the last decade, equal-channel angular pressing procedure was used for the fabrication of ultrafine-grained metals and alloys. The pl...

  10. Quadrupole-octupole coupled states in 112Cd

    The properties of negative-parity states in the 2.5 MeV region in 112Cd have been investigated with the (n,n'γ) reaction. For many of these levels, lifetimes have been measured, and B(E1) and B(E2) values for their decays have been determined. Several transitions exhibit enhanced B(E2) values for decay to the 31- octupole state, indicative of quadrupole-octupole coupled (2+circle-times 3-) states. The B(E1) values observed are typically in the range of 1 - 5x10-4 Weisskopf units (W.u.), irrespective of the final state. copyright 1999 The American Physical Society

  11. Time-dependent Hartree-Fock Study of Octupole Vibrations in doubly magic nuclei

    Simenel, C; Vo-Phuoc, K

    2016-01-01

    Octupole vibrations are studied in some doubly magic nuclei using the time-dependent Hartree-Fock (TDHF) theory with a Skyrme energy density functional. Through the use of the linear response theory, the energies and transition amplitudes of the low-lying vibrational modes for each of the nuclei were determined. Energies were found to be close to experimental results. However, transition amplitudes, quantified by the deformation parameter $\\beta_3$, are underestimated by TDHF. A comparison with single-particle excitations on the Hartree-Fock ground-state shows that the collective octupole vibrations have their energy lowered due to attractive RPA residual interaction.

  12. Deformation bands in porous sandstones, their microstructure and petrophysical properties

    2008-01-01

    Deformation bands are commonly thin tabular zones of crushed or reorganized grains that form in highly porous rocks and sediments. Unlike a fault, typically the slip is negligible in deformation bands. In this dissertation the microstructure and petrophysical properties of deformation bands have been investigated through microscopy and numerical analysis of experimental and natural examples. The experimental work consists of a series of ring-shear experiments performed on porou...

  13. Structure properties of even-even actinides at normal and super deformed shapes analysed using the Gogny force

    Mean field and beyond mean field methods implemented with the D1S force are used in large scale calculations to study the structure properties of fifty five even-even actinides at normal and isomeric potential deformations. The mass region covered is spanned by the 226-236Th, 228-242U, 232-246Pu, 238-250Cm, 238-256Cf, 242-258Fm and 250-262No nuclides. Hartree-Fock-Bogolyubov (HFB) calculations performed with constraints placed on axial and triaxial quadrupole deformations as well as octupole deformations serve to build tensors of inertia and potential energy landscapes up to very large elongations. Long lived spin isomers are investigated through blocking calculations performed with and without breaking time reversal symmetry. Configuration mixing calculations are performed to make predictions for shape isomers and π=+ vibrations in the isomeric potentials and to calculate moments of inertia at low spin. Moments of inertia are also investigated through cranking HFB calculations to high frequency so as to explore in this regime pairing properties of the D1S force in the heavy mass region. The WKB method is adopted in half-life calculations for the γ-back and fission decay modes of shape isomers. All these predictions are challenged through extensive comparisons with measurements for multipole moments, moments of inertia, spin and shape isomers as well as superdeformed phonons, inner and outer potential barrier heights, and shape isomer lifetimes. Most predictions match the experimental data. Finally we predict a shallow minimum on top of the triaxial inner barriers of N∼154 nuclei. This topological property offers a possible explanation for the unexpected structures observed in fission transmissions measured a long time ago for 252Cf and neighboring nuclei

  14. Soft octupole vibrations with K=0 and K≠ built on superdeformed rotational bands and static pairing correlations

    Properties of low-lying octupole vibrations (with K=0, 1, 2 and 3) built on superdeformed rotational bands are investigated by means of the RPA in a uniformly rotating frame. Large configuration space composed of 9 major shells is used. Numerical examples are presented for the superdeformed band in 192Hg as a typical case where appreciable amount of static pairing correlations remains at finite values of the rotational frequency. We obtain strongly collective low-frequency octupole vibrations with K=0, 1 and 2. It is shown that the properties of the K=1 octupole vibrations are especially sensitive to the static pairing correlations. The Coriolis-mixings among these soft octupole vibrations are shown to become important when the rotational frequency ωrot > or approx. 0.2 MeV/ℎ. (author)

  15. Soft Octupole Vibrations with K = 0 and K !=q 0 Built on Superdeformed Rotational Bands and Static Pairing Correlations

    Mizutori, S.; Shimizu, Y. R.; Matsuyanagi, K.

    1991-07-01

    Properties of low-lying octupole vibrations (with K = 0, 1, 2 and 3) built on superdeformed rotational bands are investigated by means of the RPA in a uniformly rotating frame. Large configuration space composed of 9 major shells is used. Numerical examples are presented for the superdeformed band in (192) Hg as a typical case where appreciable amount of static pairing correlations remains at finite values of the rotational frequency. We obtain strongly collective low-frequency octupole vibrations with K = 0, 1 and 2. It is shown that the properties of the K = 1 octupole vibrations are especially sensitive to the static pairing correlations. The Coriolis-mixings among these soft octupole vibrations are shown to become important when the rotational frequency omega_{mathrm{rot}} gtrsim 0.2 MeV/hbar.

  16. Application of the triaxial quadrupole-octupole rotor to the ground and negative-parity levels of actinide nuclei

    Nadirbekov, M S; Strecker, M; Scheid, W

    2016-01-01

    In this work we examine the possibility to describe yrast positive- and negative-parity excitations of deformed even-even nuclei through a collective rotation model in which the nuclear surface is characterized by triaxial quadrupole and octupole deformations. The nuclear moments of inertia are expressed as sums of quadrupole and octupole parts. By assuming an adiabatic separation of rotation and vibration degrees of freedom we suppose that the structure of the positive- and negative- parity bands may be determined by the triaxial-rigid-rotor motion of the nucleus. By diagonalizing the Hamiltonian in a symmetrized rotor basis with embedded parity we obtain a model description for the yrast positive- and negative-parity bands in several actinide nuclei. We show that the energy displacement between the opposite-parity sequences can be explained as the result of the quadrupole-octupole triaxiality.

  17. Some properties of deformed $q$-numbers

    Lobo, Thierry C Petit; Pinho, Suani T R; Borges, Ernesto P

    2009-01-01

    Nonextensive statistical mechanics has been a source of investigation in mathematical structures such as deformed algebraic structures. In this work, we present some consequences of $q$-operations on the construction of $q$-numbers for all numerical sets. Based on such a construction, we present a new product that distributes over the $q$-sum. Finally, we present different patterns of $q$-Pascal's triangles, based on $q$-sum, whose elements are $q$-numbers.

  18. Octupole correlations in 143 Ba and 147 Pr

    High spin states in neutron-rich odd-Z 143,145 Ba nuclei have been investigated from the study of prompt γ-rays in the spontaneous fission of 252 Cf. Alternating parity bands are identified for the first time in 145 Ba and extended in 143 Ba. A new side band with equal, constant dynamic and kinematic moments of inertia equal to the rigid body value, as found in superdeformed bands, is discovered in 145 Ba. Enhanced E1 transitions between the negative- and positive-parity bands in these nuclei give evidence for strong octupole deformation in 143 Ba and in 145 Ba. These collective bands show competition and co-existence between symmetric and asymmetric shapes in 145 Ba. The first evidence is found for crossing M1 and E1 transitions between the s = +i and s = -i doublets in 143 Ba. Neutron-rich 147 Pr also was studied in the spontaneous fission of 252 Cf. Possible parity doublets observed in 147 Pr with N = 88 indicate that neutron-rich 59147 Pr88 nucleus exhibits strong octupole correlations like those observed in the 58146 Ce88 core. (authors)

  19. Corneal biomechanical properties from air-puff corneal deformation imaging

    Marcos, Susana; Kling, Sabine; Bekesi, Nandor; Dorronsoro, Carlos

    2014-02-01

    The combination of air-puff systems with real-time corneal imaging (i.e. Optical Coherence Tomography (OCT), or Scheimpflug) is a promising approach to assess the dynamic biomechanical properties of the corneal tissue in vivo. In this study we present an experimental system which, together with finite element modeling, allows measurements of corneal biomechanical properties from corneal deformation imaging, both ex vivo and in vivo. A spectral OCT instrument combined with an air puff from a non-contact tonometer in a non-collinear configuration was used to image the corneal deformation over full corneal cross-sections, as well as to obtain high speed measurements of the temporal deformation of the corneal apex. Quantitative analysis allows direct extraction of several deformation parameters, such as apex indentation across time, maximal indentation depth, temporal symmetry and peak distance at maximal deformation. The potential of the technique is demonstrated and compared to air-puff imaging with Scheimpflug. Measurements ex vivo were performed on 14 freshly enucleated porcine eyes and five human donor eyes. Measurements in vivo were performed on nine human eyes. Corneal deformation was studied as a function of Intraocular Pressure (IOP, 15-45 mmHg), dehydration, changes in corneal rigidity (produced by UV corneal cross-linking, CXL), and different boundary conditions (sclera, ocular muscles). Geometrical deformation parameters were used as input for inverse finite element simulation to retrieve the corneal dynamic elastic and viscoelastic parameters. Temporal and spatial deformation profiles were very sensitive to the IOP. CXL produced a significant reduction of the cornea indentation (1.41x), and a change in the temporal symmetry of the corneal deformation profile (1.65x), indicating a change in the viscoelastic properties with treatment. Combining air-puff with dynamic imaging and finite element modeling allows characterizing the corneal biomechanics in-vivo.

  20. Symmetry properties of energy bands for some deformed light nuclei

    According to the Bohr's Theory, the first excited states of deformed nuclei are well represented through simple rotational states which are denoted 0+, 2+, 4+, etc., respectively. The ratio of the high excitation energies to the first rotational state (2+) for deformed nuclei demonstrates a well consistency with the integer numbers. These ratio show that there is a symmetry property of deformed nuclei in the excited bands. In this study we have investigated the symmetry properties of energy bands for some deformed light nuclei ( 40K, 52Cr, 55Mn, 58Fe, 59Ni, 60Co) by using of K-quantum number which is projection of the total angular momentum on the axis of symmetry of a nucleus, and also determined energy bands having symmetry

  1. Influence of deformation technology on fatigue properties of titanium

    Jn Miche?; Marin Burk; Petra Lackov

    2014-01-01

    The influence of commercially pure Titanium microstructure on fatigue properties and their improvement or deterioration is analyzed in the presented contribution. One tested material was after cold drawing the other after severe plastic deformation by Equal Channel Angular Pressing (ECAP). Intense plastic deformation (ECAP) resulted in yield point 100 % higher and UTS 97% higher than obtained by traditional cold drawing. The ductility was 57% lower than for cold drawing. However, the fatigue ...

  2. Deformation Properties of TiNi Shape Memory Alloy

    Tobushi, H.; Lin, P.; K.Tanaka; Lexcellent, C.; Ikai, A

    1995-01-01

    In order to describe the deformation properties due to the martensitic transformation and the R-phase transformation of TiNi shape memory alloy, a thermomechanical constitutive equation considering the volume fractions of induced phases associated with both transformations is developed. The proposed constitutive equation expresses well the properties of the shape memory effect, pseudoelasticity and recovery stress.

  3. Mean field study of the quadrupole-octupole degree of freedom in the spdf boson model

    We present a mean field study of the quadrupole-octupole degree of freedom in collective nuclei within the framework of the spdf-boson model. For realistic choices of the Hamiltonian parameters, the ground state of the system is shown to remain axially symmetric, which considerably simplifies the mean field treatment. The critical point for the onset of octupole deformation in quadrupole deformed systems is identified in the parameter space and importance of the parity projection in this process is emphasized. A systematic survey of excitation energies and electric transitions for one-phonon states is given, which will provide useful guidance for detailed studies of negative parity states within the spdf-boson model

  4. Microscopic description of octupole shape-phase transitions in light actinides and rare-earth nuclei

    Nomura, K; Niksic, T; Lu, Bing-Nan

    2014-01-01

    A systematic analysis of low-lying quadrupole and octupole collective states is presented, based on the microscopic energy density functional framework. By mapping the deformation constrained self-consistent axially symmetric mean-field energy surfaces onto the equivalent Hamiltonian of the $sdf$ interacting boson model (IBM), that is, onto the energy expectation value in the boson condensate state, the Hamiltonian parameters are determined. The study is based on the global relativistic energy density functional DD-PC1. The resulting IBM Hamiltonian is used to calculate excitation spectra and transition rates for the positive- and negative-parity collective states in four isotopic chains characteristic for two regions of octupole deformation and collectivity: Th, Ra, Sm and Ba. Consistent with the empirical trend, the microscopic calculation based on the systematics of $\\beta_{2}$-$\\beta_{3}$ energy maps, the resulting low-lying negative-parity bands and transition rates show evidence of a shape transition be...

  5. q-deformed noncommutative cat states and their nonclassical properties

    Dey, Sanjib

    2015-01-01

    We study several classical like properties of q-deformed nonlinear coherent states as well as nonclassical behaviours of q-deformed version of the Schrodinger cat states in noncommutative space. Coherent states in q-deformed space are found to be minimum uncertainty states together with the squeezed photon distributions unlike the ordinary systems, where the photon distributions are always Poissonian. Several advantages of utilising cat states in noncommutative space over the standard quantum mechanical spaces have been reported here. For instance, the q-deformed parameter has been utilised to improve the squeezing of the quadrature beyond the ordinary case. Most importantly, the parameter provides an extra degree of freedom by which we achieve both quadrature squeezed and number squeezed cat states at the same time in a single system, which is impossible to achieve from ordinary cat states.

  6. Nd-Fe-B-Cu hot deformation processing: a comparison of deformation modes, microstructural development and magnetic properties

    Due to its relative simplicity and low cost the hot deformation of Nd-Fe-B ingots is rapidly reaching the status of a valid alternative to sintering. Among the possible deformation modes, pressing, rolling and forging are perhaps the most successful. This paper describes the research programme undertaken so far, by discussing the relationship between deformation mode, microstructure and magnetic properties of magnets produced by hot deformation mode, microstructure and magnetic properties of magnets produced by hot deformation of a number of Nd-fe-B-Cu alloys. Microstructural observation showed that both pressed and forged samples are characterized by a heterogeneous microstructure and from magnetic measurements it was concluded that magnetic properties differ when taken in the center or in the periphery of the sample. On the other hand roller magnets were homogeneous both in terms of microstructure and magnetic properties, and interpretations of the mechanisms of texture development and of microstructural development of hot deformed magnets is put forward. (author)

  7. Strength and Deformation Properties of Tertiary Clay at Moesgaard Museum

    Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    The tertiary clay at Moesgaard Museum near Aarhus in the eastern part of Jutland in Denmark is a highly plastic, glacially disturbed nappe of Viborg Clay. The clay is characterised as a swelling soil, which could lead to damaging of the building due to additional heave of the soil. To take this...... characteristic, as well as the strength and deformation properties, into account during the design phase, two consolidation tests and one triaxial test have been conducted. This paper evaluates the results of the laboratory tests leading to the preconsolidation stress, the deformation parameters consisting of...

  8. Study of the octupole modes in the atomic nucleus of 156Gd: experimental search of the tetrahedral symmetry

    Geometrical symmetries play an important role in the understanding of all physical systems. In nuclear structure they are linked to the shape of the mean-field used to describe the atomic nuclei properties. In the framework of this thesis, we have used the predictions obtained with the help of the nuclear mean-field Hamiltonian with the Universal Woods-Saxon potential to study the effects of the so-called 'High-Rank' symmetries. These point-group symmetries lead to a nuclear state degeneracy of the order of 4. It is predicted that the tetrahedral symmetry affects the stability of nuclei close to the tetrahedral magic numbers [Z,N]=[32,40,56,64,70,90-94,136]. We have selected the Rare-Earth region close to the tetrahedral doubly magic nucleus 154Gd for our study. In this region, there exists negative parity structures poorly understood. Yet the tetrahedral symmetry, as related to a non-axial octupole deformation, breaks the reflection symmetry and leads to the negative parity states. Following a systematics of experimental properties of the nuclei in this region, we have selected 156Gd as the object of our study for the octupole excitation modes. We have used the reduced transitions probabilities to discriminate between these modes. To achieve this goal, we have performed three gamma spectroscopy experiments at the ILL in Grenoble with the EXILL and GAMS detectors to measure the lifetimes and the gamma transition intensities from the candidate states. The analysis of our results shows that including the tetrahedral shape helps to understand the dipole transition probabilities. This result will open new experimental and theoretical perspectives. (author)

  9. Measuring the full transverse beam matrix using a single octupole

    Ögren, Jim; Ruber, Roger; Ziemann, Volker; Farabolini, W.

    2015-01-01

    We propose a method to fully determine the transverse beam matrix using a simple setup consisting of two steering magnets, an octupole field and a screen. This works in principle for any multipole field, i.e., sextupole, octupole magnet or a radio frequency structure with a multipole field. We have experimentally verified the method at the Compact Linear Collider Test Facility 3 at CERN using a Compact Linear Collider accelerating structure, which has an octupole component of the radio freque...

  10. Evidence for octupole vibration in the superdeformed well of {sup 190}Hg from eurogam

    Crowell, B.; Carpenter, M.P.; Janssens, R.V.F. [and others

    1995-08-01

    Gammasphere experiments in 1993-94 brought to light the existence of an excited superdeformed (SD) band in {sup 190}Hg with the unusual property of decaying entirely to the lowest (yrast) SD band over 3-4 transitions, rather than to the normally deformed states as is usually the case in the A {approximately} 150 and A {approximately} 190 regions of superdeformation. Although M1 transitions between signature-partner SD bands were previously observed in {sup 193}Hg, no such mechanism was available to explain the situation in the even-even nucleus {sup 190}Hg, whose yrast SD band has no signature partner. The best explanation appears to lie in long-standing theoretical predictions that the SD minimum in the potential energy surface would be quite soft with respect to octupole vibrations. This would lead to enhanced E1 transitions connecting the one-phonon and zero-phonon states. The data and this interpretation were published. A shortcoming of the Gammasphere experiments was that they did not allow the definitive measurement of the energies of the gamma-ray transitions connecting the two bands, due to the very weak population of the excited band ({approximately}0.05% of the {sup 190}Hg channel) and also partly, we believed, to the angular distributions of the transitions, which were peaked near 90 degrees, where Gammasphere had few detectors.

  11. Experimental fusion barrier distributions reflecting projectile octupole state coupling to prolate and oblate target nuclei

    Fusion excitation functions have been measured spanning the entire barrier region in 1 MeV energy steps for the two systems 40Ca+192Os,194Pt. Precautions were taken to ensure sufficiently small errors to allow for extraction of the distribution of fusion barriers from the second differential of the product of E and ?. These results are compared with coupled channels calculations which take into account the most important degrees of freedom of both projectile and target. The influence of the prolate deformation of 192Os and the oblate deformation of 192Pt as well as the octupole vibration of 40Ca is apparent. copyright 1996 The American Physical Society

  12. Deformation bands in porous sandstones their microstructure and petrophysical properties

    Torabi, Anita

    2007-12-15

    Deformation bands are commonly thin tabular zones of crushed or reorganized grains that form in highly porous rocks and sediments. Unlike a fault, typically the slip is negligible in deformation bands. In this dissertation the microstructure and petrophysical properties of deformation bands have been investigated through microscopy and numerical analysis of experimental and natural examples. The experimental work consists of a series of ring-shear experiments performed on porous sand at 5 and 20 MPa normal stresses and followed by microscopic examination of thin sections from the sheared samples. The results of the ring-shear experiments and comparison of them to natural deformation bands reveals that burial depth (level of normal stress in the experiments) and the amount of shear displacement during deformation are the two significant factors influencing the mode in which grains break and the type of shear zone that forms. Two end-member types of experimental shear zones were identified: (a) Shear zones with diffuse boundaries, which formed at low levels of normal stress and/or shear displacement; and (b) Shear zones with sharp boundaries, which formed at higher levels of normal stress and/or shear displacement. Our interpretation is that with increasing burial depth (approximately more than one kilometer, simulated in the experiments by higher levels of normal stress), the predominant mode of grain fracturing changes from flaking to splitting; which facilitates the formation of sharp-boundary shear zones. This change to grain splitting increases the power law dimension of the grain size distribution (D is about 1.5 in sharp boundary shear zones). Based on our observations, initial grain size has no influence in the deformation behavior of the sand at 5 MPa normal stresses. A new type of cataclastic deformation band is described through outcrop and microscopic studies; here termed a 'slipped deformation band'. Whereas previously reported cataclastic deformation bands are characterized by strain hardening, these new bands feature a central slip surface, which indicates late strain softening. They lack the characteristic compaction envelop, and are typified by higher porosity and lower permeability than previously-described cataclastic deformation bands. Intense background fracturing of the host rock and significant initial porosity are considered to be important in creating these newly-discovered deformation bands. In a related study, we investigate, for millimeter- wide deformation bands, the scale limitation inherent in laboratory measurements of porosity and permeability. The scale limitations imposed by the deformation band relative to the physical sample size motivated us to develop a new method for determining porosity and permeability based on image processing. While plug measurements measure the effective permeability across a 25.4 mm (1 inch) long sample, which includes both host rock and deformation band, the method presented here provides a means to estimate porosity and permeability of deformation band on microscale. This method utilizes low-order (one- and two orders) spatial correlation functions to analyze high-resolution, high-magnification backscatter images, to estimate the porosity and specific surface area of the pore-grain interface in the deformed sandstones. Further, this work demonstrates the use of a modified version of the Kozeny-Carmen relation to calculate permeability by using porosity and specific surface area obtained through the image processing. The result shows that permeability difference between the band and the host rock is up to four orders of magnitude. Moreover, the porosities and permeabilities estimated from image processing are lower than those obtained from their plug measurements; hence the traditional laboratory measurements have been overestimating permeability because of the previously-unrecognized scale problem. In addition, the image processing results clearly show that, as a result of microstructural variation, both porosity and permeability vary along the length of individual deformation bands, with permeability variations of up to two orders of magnitude. Such petrophysical variations are found in several types of deformation bands (disaggregation, cataclastic and dissolution bands), but the range depends on the deformation mechanisms, in particular on the degree of (i) cataclasis, (ii) dissolution in cataclastic and dissolution bands, and (iii) on the phyllosilicate content in disaggregation bands. This microscopic anisotropy in the petrophysical properties of deformation bands opens up a new and fruitful area for further research. Our results show that for phyllosilicate bands the band thickness is related to the phyllosilicate content, whereas for cataclastic bands no apparent correlation was found between thickness and intensity of cataclasis. (author). refs., figs

  13. Microstructure, properties and hot deformability of the new maraging steels

    S.J. Pawlak

    2008-07-01

    Full Text Available Purpose: The effects of relevant metallurgical factors on the structure, fracture mode and properties of the high cobalt and cobalt free maraging steel has been studied. The aim was to better understand structure-property relations and enhance mechanical properties of the steels. To provide data needed for production and manufacturing technology, the high temperature deformability using physical simulation method was used.Design/methodology/approach: To study structure-property relation, broad range of the experimental techniques was used: quantitative metallography, X-ray diffraction phase analysis, transmission electron microscopy and SEM fractography. The flow properties in the range of hot working processes were determined by physical simulation approach, using Gleeble 3800 system.Findings: The cobalt-free maraging steel proved to be a valuable structural steel. At much higher fracture toughness it had only about 100 MPa lower yield stress, compared to that of high cobalt steel. Fracture surface morphologies were highly dependent on the steel grade and type of the mechanical test. The hot stress-strain characteristics were established for cobalt free maraging steel and compared to that of a stainless steel.Research limitations/implications: To fully evaluate potential field of applications, deeper comparative studies of the high cobalt and cobalt-free maraging steels are needed, particularly fracture modes and service properties of some parts.Practical implications: Very high mechanical properties and fracture toughness values obtained for the steels studied, make them suitable for advanced structural applications. The studies on the hot deformation behaviour of the steels are of practical value for the hot working process development.Originality/value: Detailed evaluation of the metallurgical purity, microstructure and fracture modes, allowed for better understanding of the microstructure-property relationships in selected high strength steels. The results obtained are of practical value for the development, production and manufacture of the high strength maraging steels with improved properties.

  14. Effect of deformation diagram on molybdenum structure and properties

    Effect of deformation diagram on a tendency to lamination and mechanical properties of disks made of molybdenum alloy is studied. Investigated samples were subjected to hot rolling or forging. X-ray structural analysis of texture is carried out along with estimation of the level of mechanical properties across item cross section. Sample mechanical bending tests were conducted. Sample microstructure is also studied. It is shown that rolled molybdenum has a tendency to lamination, but forged molybdenum is free of such a tendency. Forged sample ductility is practically equal in all directionse but rolled sample ductility in a surface layer is high and decreases with depth. A conclusion is drawn that forged sample grains in a setting surface are equiaxial, but distinct deformation texture is observed for rolled samples and their grains are elongated in the direction of rolling. A conclusion is made that a flow diagram of the process of disk fabrication by forging or stamping ppovides a necessary complex of physicomechanical properties of metal as compared to polling, and metal discharge coefficient decreases sharply in this case

  15. Rock mass deformation properties of closely jointed basalt

    The deformational behavior of the Columbia River basalt is being investigated as part of a comprehensive site characterization program intended to determine the feasibility of constructing a nuclear waste repository in basalt at Hanford, Washington. Direct field measurements were conducted in a 2-m cube of basalt to obtain truly representative rock mass deformation properties. Load was applied to the test block in three orthogonal directions through the use of flat jacks in two perpendicular planes and a cable anchor system in the third. This configuration allowed the block to be placed in a simulated triaxial stress state at stress levels up to 12.5 MPa. The deformation at the center of the test block was monitored through the use of an optical measurement system developed for this project. The results indicate that the vertically oriented columnar joints have a significant influence on the deformation behavior of the basalt. The modulus in the direction parallel to the column axis was approx. 30 GPa, while the modulus value perpendicular to the columns was approx. 20 GPa. Laboratory measurements of intact specimens taken from this area yielded a value of 80 GPa with no indication of anisotropy. Hysteresis was observed in all loading cycles, but was distinctly more pronounced perpendicular to the column axis, indicative of significant joint displacement in this direction. The results of this test represent the first true rock mass modulus data obtained in closely jointed rock on a large scale. These measurement methods have eliminated many of the ambiguities associated with borehole jacking and surface measurement techniques

  16. Octupole vibrations in the even mercury and lead isotopes

    Prominent groups are observed corresponding to excited states in the region of 2.6 MeV in the scattering of 24 and 27 MeV α-particles from 198200202204Hg and 204206208Pb. For each of the Pb isotopes the state concerned is identified with the known 3- octupole vibration. Angular distribution measurements for scattering to the Pb and 204Hg states are in agreement with octupole-vibration coupled-channels predictions, and systematic trends suggest that the states observed in the isotopes 198200202Hg can also be attributed to octupole vibrations

  17. Octupole correlations in neutron rich, odd-A lanthanum nuclei

    Neutron-rich, odd-Z nuclei 145La and 147La populated in spontaneous fission of 248Cm were studied using the EUROGAM array. The experiment indicates the presence of similar octupole correlations in the studied La isotopes as found in the barium core nuclei. Alternating-parity structures were found in 145La, indicating enhanced octupole correlations, as observed in 144Ba, while in 147La octupole effects are weakened by alignment phenomena, as seen in the core nucleus 146Ba. copyright 1996 The American Physical Society

  18. Photoelectron angular distribution parameters in the octupole approximation

    The expression is presented for the X-ray electron spectra (XES) intensity excited by unpolarized radiation with due account of octupole transitions. The nondipole parameters including octupole transition parameters are calculated in relativistic approximation both for polarized and unpolarized radiation for atoms from Li to Ne. The calculations are performed for 1s-shell and for 2s- and 2p-shells for different photoelectron energies. The substantial contributions (up to 10%) for the XES-intensity are found for 1s-shell when kinetic energy is 5000 eV and 10000 eV. In other cases the octupole contributions are less than 1%

  19. Measuring the full transverse beam matrix using a single octupole

    Ögren, J.; Ruber, R.; Ziemann, V.; Farabolini, W.

    2015-07-01

    We propose a method to fully determine the transverse beam matrix using a simple setup consisting of two steering magnets, an octupole field and a screen. This works in principle for any multipole field, i.e., sextupole, octupole magnet or a radio frequency structure with a multipole field. We have experimentally verified the method at the Compact Linear Collider Test Facility 3 at CERN using a Compact Linear Collider accelerating structure, which has an octupole component of the radio frequency fields. By observing the position shifts of the beam centroid together with changes in transverse beam size on a screen, we determined the full transverse beam matrix, with all correlations.

  20. Octupole vibrations in rare-earth nuclei

    Buessing, Marc Andre; Elvers, Michael; Endres, Janis; Hasper, Jens; Zilges, Andreas [Institut fuer Kernphysik, Universitaet Koeln, D-50823 Koeln (Germany)

    2009-07-01

    The systematics of octupole vibrations in the region of rare-earth nuclei are still not well understood. First test measurements have been carried out at the FN Tandem accelerator of the University of Cologne. The gamma-ray spectroscopy was performed at the highly-efficient HORUS spectrometer which consists of 16 High-Purity Germanium detectors. The nucleus {sup 158}Dy has been investigated via the reactions {sup 156}Gd({alpha},2n) and {sup 149}Sm({sup 12}C,3n), furthermore the nucleus {sup 154}Dy was studied via the reaction {sup 144}Nd({sup 14}N,4n). In addition measurements with the (p,p{sup '}) reaction were carried out on the nuclei {sup 142}Nd and {sup 172}Yb. First results of these measurements are shown in the context of existing data for this mass region.

  1. Spectroscopy of quadrupole and octupole states in rare-earth nuclei from a Gogny force

    Nomura, K; Robledo, L M

    2015-01-01

    Collective quadrupole and octupole states are described in a series of Sm and Gd isotopes within the framework of the interacting boson model (IBM), whose Hamiltonian parameters are deduced from mean field calculations with the Gogny energy density functional. The link between both frameworks is the ($\\beta_2\\beta_3$) potential energy surface computed within the Hartree-Fock-Bogoliubov framework in the case of the Gogny force. The diagonalization of the IBM Hamiltonian provides excitation energies and transition strengths of an assorted set of states including both positive and negative parity states. The resultant spectroscopic properties are compared with the available experimental data and also with the results of the configuration mixing calculations with the Gogny force within the generator coordinate method (GCM). The structure of excited $0^{+}$ states and its connection with double octupole phonons is also addressed. The model is shown to describe the empirical trend of the low-energy quadrupole and o...

  2. Transient deformation properties of Zircaloy for LOCA simulation. Final report

    The creep/creep rupture anisotropic properties of Zircaloy were determined and compared by analytical techniques with ramp-pressure and ramp-temperature test results. Tests were performed over the temperature range of 6000F (5890K) to 22000F (14770K) with the emphasis on the 8000F (7000K) to 20000F (13660K) temperature levels in low pressure air (6.5 x 10-5 atm) and in a 1 atm mixture of 20% oxygen, 80% argon. Stress levels of 60 to 95% of the ultimate tensile stress were used for the majority of the tests at each of the temperature levels tested, with selected tests performed as low as 30% of the ultimate tensile stress. Biaxial and uniaxial testing modes were used to evaluate the anisotropic deformation behavior. The combination of test results and predictive analysis techniques developed as part of this program make it possible to predict the transient deformation of reactor fuel cladding during simulated LOCA conditions. Results include creep/creep rupture strain numerical constitutive relationships out of 120 seconds, computer codes and ramp test data

  3. Fluid and ionic transport properties of deformed salt rock

    This is a final report on work done on the transport properties of salt during the period 1 January 1984 to 30 June 1985. This work was directed largely at the measurement of creep-induced permeability in salt rock, at determining the permeability persistence/decay characteristics of creep-dilated salt rock under hydrostatic conditions, and at ion migration/retention experiments on both deformed and undeformed material. The permeability work was carried out using both gas (argon) and brine, and involved the design and construction of corresponding permeametry systems for use in conjunction with dilatometric triaxial testing apparatus. Ion migration/retention studies involved the use of contaminant species such as Sr2+, Cs+, Fe3+ and TcO4

  4. Effects of cold pre-deformation on aging behavior and mechanical properties of Ti-1300 alloy

    Highlights: • Cold pre-deformation influences aging behavior and mechanical properties. • The slip and twinning are the leading deformation mechanism in the Ti-1300 alloy. • Fine/uniform α precipitates are formed in the slightly deformed zones. • Coarse/needle-like α precipitates are formed in the heavily deformed zones. - Abstract: The effects of cold pre-deformation on aging behavior and mechanical properties in Ti-1300 alloy are examined using optical microscopy, scanning electron microscopy, and transmission electron microscopy analyses. Results show that cold pre-deformation markedly influences the aging behavior and mechanical properties of Ti-1300 alloys. The cold deformation mechanism of Ti-1300 alloys is found to involve the dislocation slip and twinning. The microstructures of the pre-deformation specimens, which were aged at 550 °C, comprise α phases in β matrices regardless of cold deformation reduction. Fine/uniform and coarse/needle-like α precipitates are formed in the slightly and heavily deformed zones, respectively. The Vickers hardness of Ti-1300 alloys aged after cold pre-deformation respectively decreases and increases with increased aging temperature and cold pre-deformation reduction

  5. Evolution of deformation texture and magnetic properties in a nanocrystalline nickel20 wt% cobalt alloy

    The evolution of crystallographic texture in a nanocrystalline nickel20 wt% cobalt alloy has been investigated for deformation up to large strains. The effect of texture on magnetic properties has been evaluated. The material shows characteristic copper-type texture at large strain levels. Microstructural examinations indicate that the evolution of texture is assisted by deformation-induced grain growth. The values of saturation magnetization and coercivity have been correlated with the crystallographic texture and grain size. - Highlights: The deformation of a nanocrystalline nickel-20 wt% cobalt alloy, to large strains, leads to a characteristic copper-type rolling texture. Dislocation based slip process is evident from the deformed microstructures at the later stages of deformation, while grain boundary assisted mechanisms are active during the initial stages. The activity of dislocation at higher strain levels is facilitated by deformation-induced grain growth. The evolution of magnetic properties is dependent on the deformation texture, while the effect of grain size is insignificant

  6. In-situ studies of bulk deformation structures: Static properties under load and dynamics during deformation

    Jakobsen, Bo

    2006-01-01

    width of the peaks, and spatial scanning experiments it is concluded that the individual peaks arise from individual dislocation-free regions (the subgrains) in the dislocation structure. The cloud is attributed to the dislocation rich walls. Samples deformed to 2% tensile strain were investigated under...... asymmetrical line broadening have to be reconsidered. Based on continuous deformation experiments, it is found that the dislocation patterning takes place during the deformation, and that a subgrain structure appears from the moment where plastic deformation is detected. By investigating samples under stress...... relaxation conditions, and unloading, it is found that the overall dislocation structure only depends on the maximum obtained flow stress. However, some changes in orientation and internal strain distribution between the subgrains were observed after the unloading. An in-situ stepwise straining experiment of...

  7. Effects of superplastic deformation on thermal and mechanical properties of 3Y-TZP ceramics (review)

    Our recent activities related to thermal and mechanical properties of superplastic ceramics, 3Y-TZP, are presented in this paper. These properties were obtained after the superplastic deformation process, because the effect of superplastic deformation on their properties is one of the important points from an application viewpoint of superplastic deformation such as forming and joining technologies. As for the thermal properties, specific heat was measured using the DSC method over a wide range of temperatures, from 473 K to 1273 K, with a nominal superplastic deformation strain of 70%. The crystal structure was characterised by measuring X-ray diffraction patterns, and microstructural observation was carried out using a SEM. As for the mechanical properties, dynamic hardness and Young's modulus were measured using the dynamic indentation technique with a maximum superplastic deformation of 150%. Microstructural observation was also carried out using a SEM after a thermal etching. (authors)

  8. A Summary on Landau Octupoles for the LHC

    Koutchouk, Jean-Pierre

    1998-01-01

    The justification and calculation of a Landau octupole scheme for LHC version 5 may be found in ref. [1]. This approach takes advantage of the analysis of 2D Landau damping documented in ref. [2], which shows that the stability is improved as compared to the usual 1D approach. The stability of single and multi-bunch modes for reduced beam intensity in several realistic operational LHC configurations is estimated and reported in ref. [3]. We summarise briefly in this note the above-mentioned studies and provide some missing information, such as the instability growth rates of multi-bunch modes vs chromaticity, to clarify the requirements. After discussing the stability of single bunch head-tail modes, comparing their real coherent tune shifts with tune spreads of different origin, we present stability diagrams of multi-bunch modes having complex coherent tune shifts and discuss Landau octupole schemes making use of arc octupoles or b4 spool-pieces.

  9. String field theory. Algebraic structure, deformation properties and superstrings

    This thesis discusses several aspects of string field theory. The first issue is bosonic open-closed string field theory and its associated algebraic structure - the quantum open-closed homotopy algebra. We describe the quantum open-closed homotopy algebra in the framework of homotopy involutive Lie bialgebras, as a morphism from the loop homotopy Lie algebra of closed string to the involutive Lie bialgebra on the Hochschild complex of open strings. The formulation of the classical/quantum open-closed homotopy algebra in terms of a morphism from the closed string algebra to the open string Hochschild complex reveals deformation properties of closed strings on open string field theory. In particular, we show that inequivalent classical open string field theories are parametrized by closed string backgrounds up to gauge transformations. At the quantum level the correspondence is obstructed, but for other realizations such as the topological string, a non-trivial correspondence persists. Furthermore, we proof the decomposition theorem for the loop homotopy Lie algebra of closed string field theory, which implies uniqueness of closed string field theory on a fixed conformal background. Second, the construction of string field theory can be rephrased in terms of operads. In particular, we show that the formulation of string field theory splits into two parts: The first part is based solely on the moduli space of world sheets and ensures that the perturbative string amplitudes are recovered via Feynman rules. The second part requires a choice of background and determines the real string field theory vertices. Each of these parts can be described equivalently as a morphism between appropriate cyclic and modular operads, at the classical and quantum level respectively. The algebraic structure of string field theory is then encoded in the composition of these two morphisms. Finally, we outline the construction of type II superstring field theory. Specific features of the superstring are the appearance of Ramond punctures and the picture changing operators. The sewing in the Ramond sector requires an additional constraint on the state space of the world sheet conformal field theory, such that the associated symplectic structure is non-degenerate, at least on-shell. Moreover, we formulate an appropriate minimal area metric problem for type II world sheets, which can be utilized to sketch the construction of a consistent set of geometric vertices. The algebraic structure of type II superstring field theory is that of a N = 1 loop homotopy Lie algebra at the quantum level, and that of a N = 1 homotopy Lie algebra at the classical level.

  10. Strength of octupole correlations in the actinides: contrasting behavior in the isotones 237U and 239Pu

    A study of high spin states in the odd-neutron isotones 239Pu and 237U is reported. Striking differences were found in the high-spin properties of rotational bands built on the 1/2+[631] ground states in these two nuclei. These differences mirror those observed in the even-even Pu and U immediate neighbors and appear to be related to the strength of octupole correlations

  11. Changes in microstructure and physical properties of skutterudites after severe plastic deformation

    Rogl, G.; Grytsiv, A.; Buršík, Jiří; Horky, J.; Anbalagan, R.; Bauer, E.; Mallik, R.Ch.; Rogl, P.; Zehetbauer, M.

    2015-01-01

    Roč. 17, č. 5 (2015), s. 3715-3722. ISSN 1463-9076 Institutional support: RVO:68081723 Keywords : physical properties * plastic deformation * TEM, SEM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.493, year: 2014

  12. Food gels filled with emulsion droplets : linking large deformation properties to sensory perception

    Sala, G.

    2007-01-01

    Key words: polymer gels, particle gels, emulsion, large deformation, friction, sensory This thesis reports studies on the large deformation and lubrication properties of emulsion-filled gels and the way these properties are related to the sensory perception of the gels. The design of the studies included polymer and particle gels containing oil droplets of which the interaction with the gel matrix was varied, resulting in droplets either bound or unbound to the matrix. The unique combinatio...

  13. Mechanical properties of hot deformed Inconel 718 and X750

    A. Nowotnik

    2012-02-01

    Full Text Available Purpose: Variations of a flow stress vs. true strain illustrate behavior of material during plastic deformation. Stress-strain relationship is generally evaluated by a torsion, compression and tensile tests.Design/methodology/approach: Compression tests were carried out on precipitations hardenable nickel based superalloys of Inconel 718 and X750 at constant true strain rates of 10-4, 4x10-4s-1 within temperature through which precipitation hardening phases process occurred (720-1150C using thermomechanical simulator Gleeble and dilatometer Baehr 850D/L equipped with compression unit. True stress-true strain curves analysis of hot deformed alloys were described.Findings: On the basis of received flow stress values activation energy of a high-temperature deformation process was estimated. Mathematical dependences (?pl -T i ?pl - ? and compression data were used to determine materials constants. These constants allow to derive a formula that describes the relationship between strain rate (?, deformation temperature (T and flow stress ?pl.Research limitations/implications: Study the flow stress will be continued on the samples after the aging process.Practical implications: The results of high-temperature deformation of the examined Inconel alloys may possibly find some practical use in the workshop practice to predict a flow stress values, but only within particular temperature and strain rate ranges. The results of the study can be used in the aerospace industry to produce blades for jet engines.Originality/value: The results of the study can be used in the aerospace industry to produce blades for jet engines.

  14. Tensile Properties and Deformation Characteristics of a Ni-Fe-Base Superalloy for Steam Boiler Applications

    Zhong, Zhihong; Gu, Yuefeng; Yuan, Yong; Shi, Zhan

    2014-01-01

    Ni-Fe-base superalloys due to their good manufacturability and low cost are the proper candidates for boiler materials in advanced power plants. The major concerns with Ni-Fe-base superalloys are the insufficient mechanical properties at elevated temperatures. In this paper, tensile properties, deformation, and fracture characteristics of a Ni-Fe-base superalloy primarily strengthened by γ' precipitates have been investigated from room temperature to 1073 K (800 °C). The results showed a gradual decrease in the strength up to about 973 K (700 °C) followed by a rapid drop above this temperature and a ductility minimum at around 973 K (700 °C). The fracture surfaces were studied using scanning electron microscopy and the deformation mechanisms were determined by the observation of deformed microstructures using transmission electron microscopy. An attempt has been made to correlate the tensile properties and fracture characteristics at different temperatures with the observed deformation mechanisms.

  15. The influence of large deformations on mechanical properties of sinusoidal ligament structures

    Strek, Tomasz; Jopek, Hubert; Wojciechowski, Krzysztof W.

    2016-05-01

    Studies of mechanical properties of materials, both theoretical and experimental, usually deal with linear characteristics assuming a small range of deformations. In particular, not much research has been published devoted to large deformations of auxetic structures – i.e. structures exhibiting negative Poisson’s ratio. This paper is focused on mechanical properties of selected structures that are subject to large deformations. Four examples of structure built of sinusoidal ligaments are studied and for each geometry the impact of deformation size and geometrical parameters on the effective mechanical properties of these structures are investigated. It is shown that some of them are auxetic when compressed and non-auxetic when stretched. Geometrical parameters describing sinusoidal shape of ligaments strongly affect effective mechanical properties of the structure. In some cases of deformation, the increase of the value of amplitude of the sinusoidal shape decreases the effective Poisson’s ratio by 0.7. Therefore the influence of geometry, as well as the arrangement of ligaments allows for smart control of mechanical properties of the sinusoidal ligament structure being considered. Given the large deformation of the structure, both a linear elastic material model, and a hyperelastic Neo-Hookean material model are used.

  16. Transient deformation properties of Zircaloy for LOCA simulation. Final report

    Hann, C. R.; Mohr, C. L.; Busness, K. M.; Olson, N. J.; Reich, F. R.; Stewart, K. B.

    1980-05-01

    This experimental data report is Volume 4 of a series of 5 volumes describing the oxidation and deformation rate behavior of Zircaloy cladding under simulated LOCA conditions. It contains listings of strain versus stress, time, and temperature evaluated from the numerical constitutive relationships and the original data used to develop them. This volume also contains listings of the ramp load, pressure, and temperature test data from both current and previous phases of the series, as well as material describing applications of the data.

  17. Transient deformation properties of Zircaloy for LOCA simulation. Final report

    This experimental data report is Volume 4 of a series of 5 volumes describing the oxidation and deformation rate behavior of Zircaloy cladding under simulated LOCA conditions. It contains listings of strain versus stress, time, and temperature evaluated from the numerical constitutive relationships and the original data used to develop them. This volume also contains listings of the ramp load, pressure, and temperature test data from both current and previous phases of the series, as well as material describing applications of the data

  18. Mechanical properties of hot deformed Inconel 718 and X750

    A. Nowotnik; P. P?drak; J. Sieniawski; M. Gral

    2012-01-01

    Purpose: Variations of a flow stress vs. true strain illustrate behavior of material during plastic deformation. Stress-strain relationship is generally evaluated by a torsion, compression and tensile tests.Design/methodology/approach: Compression tests were carried out on precipitations hardenable nickel based superalloys of Inconel 718 and X750 at constant true strain rates of 10-4, 4x10-4s-1 within temperature through which precipitation hardening phases process occurred (720-1150C) using...

  19. Tidal deformations of a spinning compact object

    Pani, Paolo; Gualtieri, Leonardo; Maselli, Andrea; Ferrari, Valeria

    2015-07-01

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the tidal Love numbers in general relativity, which are due to the difficulty in separating the tidal field from the linear response of the object in the solution, even in the static case. By extending the standard procedure to identify the linear response in the static case, we prove analytically that the Love numbers of a Kerr black hole remain zero to second order in the spin. As a by-product, we provide the explicit form for a slowly-rotating, tidally-deformed Kerr black hole to quadratic order in the spin, and discuss its geodesic and geometrical properties.

  20. The formation and deformation of protein structures with viscoelastic properties

    Riemsdijk, van, W.H.

    2011-01-01

    This study describes the formation of a gluten substitute.   Chapter 1 describes the properties that are necessary to obtain a gluten substitute.   Chapter 2 describes the formation and properties of protein particle suspensions. Two proteins with different intrinsic properties, gelatin and whey protein, were selected as model materials.   Chapter 3 describes the effects of simple shear flow on the formation and properties of gelatin particle suspensions. The application of wel...

  1. Deformation and elastic properties of WC-Co hard alloys during micro- and macroindentation

    Deformation properties of the alloys and their components are studied during micro- and macroindentation, with recording the penetration strength-depth diagram. Specimens of hard tungsten alloys with 4-98 wt.%Co are studied. Deformation work of the WC-Co alloys during micro- and macroindentation is determined and its variation depending on the cobalt phase content is studied. The work of deformation during constant depth of indentor penetration is shown to be a sensitive characteristics with respect to the structure of hard tungsten alloys

  2. Deslocation structure and mechanical properties of ?-iron in dependence on plastic deformation conditions

    Investigations of dislocation structure and mechanical properties of iron after rolling deformation in shaped rolls and after hydroextrusion are conducted. It is shown that dislocation iron structure slightly changes with deformation degree after rolling in shaped rolls and annealing and it is characterized by low density of screw dislocations. Cold brittleness temperature decreases in the result of rolling and the succeeding recrystallization and impact strength increases both at room temperature and at low temperatures. Screw dislocations having high Peierls barrier prevail in the structure after hydroextrusions. The iron deformed by hydroextrusion at 400 mPa and higher after annealing has high cold brittleness temperature and low impact strength

  3. Effect of High-Temperature Severe Plastic Deformation on Microstructure and Mechanical Properties of IF Steel

    Jindal, Vikas; Rupa, P. K. P.; Mandal, G. K.; Srivastava, V. C.

    2014-06-01

    Extensive research work has been carried out on interstitial-free steel to understand its response to deformation; particularly, the behavior during severe plastic deformation (SPD). However, most of these studies were mainly undertaken in the ferritic regime. The present investigation reports the initial results of our attempt to employ accumulative roll bonding (ARB), one of the variants of SPD, at a high temperature (950 °C). A considerable grain refinement has been observed, which may be attributed to the severity of deformation and recrystallisation at high temperatures. Nanoindentation tests have been performed at various stages of ARB process to understand the evolution of mechanical properties.

  4. Mathematical description of properties of a weakly deformed Gauss peak. 1

    The properties of the weakly deformed Gaussian peak are described by given formulas. The moment generating function and all the higher moments of this weakly deformed Gaussian peak density function are calculated by closed integrations. The density function is useful for the design of Maximum-Likelihood peak shape parameter estimators and the application of spectral techniques with multi-channel spectra. Numerical calculations use the well known Gaussian error integral and can be done by programmable microcomputers or programmable pocket calculators. (author)

  5. Effect of viscosity of petroleum products on deformation properties of concrete

    A.P. Svintsov; Yu.V. Nikolenko; M.I. Kharun; A.S. Kazakov

    2014-01-01

    This paper presents the results of studies of the effect of petroleum products, impregnating in concrete, on its deformation properties. Petroleum products, impregnating in concrete and reinforced concrete structures, have a negative impact on their strength and deformation characteristics. The negative impact of petroleum products on concrete and reinforced concrete is associated with changes in the hydration process of cement, as well as changes in the structure of the concrete. Strength an...

  6. The impact of cold deformation, annealing temperatures and chemical assays on the mechanical properties of platinum

    Trumić B.; Stanković D.; Ivanović A.

    2010-01-01

    In order to form the necessary data base on platinum and platinum metals, certain tests were carried out on platinum samples of different purity of 99.5%, 99.9% and 99.99%. The degree of cold deformation, annealing temperature and chemical assays were tested as well as their impact on the mechanical properties of platinum. The Vickers hardness (HV) values were determined with different deformation degree, starting from annealing temperatures for platinum of different purity and tensile streng...

  7. Structure properties of 226Th and 256,258,260Fm fission fragments: Mean-field analysis with the Gogny force

    The constrained Hartree-Fock-Bogoliubov method is used with the Gogny interaction D1S to calculate potential energy surfaces of fissioning nuclei 226Th and 256,258,260Fm up to very large deformations. The constraints employed are the mass quadrupole and octupole moments. In this subspace of collective coordinates, many scission configurations are identified ranging from symmetric to highly asymmetric fragmentations. Corresponding fragment properties at scission are derived yielding fragment deformations, deformation energies, energy partitioning, neutron binding energies at scission, neutron multiplicities, charge polarization, and total fragment kinetic energies

  8. Correction of chromatic and geometric aberrations using sextupoles and octupoles

    The procedure for applying some chromatic corrections to a final transport line, neglecting space charge, utilizing the method suggested by Brown is described. The possibility of including octupoles into a point-to-point triplet system, as outlined by Fenster is studied. Positive results were obtained in both cases: (i) using 2 + I correcting sections with two pairs of non-interlaced sextupoles increased the fraction of beam with ΔP/P = 1% onto a 0.1 cm radius target by more than a factor of 1.75; (ii) six octupoles placed into a point-to-point triplet system increased the fraction of a full emittance ΔP/P = 0% beam striking a 0.1 cm radius target by a factor of 2.5

  9. Mechanical property of superplastic-deformed ceramics by micro-indentation method

    A neutron irradiation test on superplastic ceramic materials at high temperature has been proposed as an innovative basic research on high-temperature engineering using the High Temperature Engineering Test Reactor (HTTR). We investigated mechanical properties, such as the hardness and Young's modulus, of ceramic specimens after superplastic deformation. The tested material was 3Y-TZP (3mol% Yttria stabilized Tetragonal Zirconia Polycrystal) which is one of the representative superplastic ceramics. The properties were measured by a microindentation method. We also studied the relationship between crystal microstructures and the mechanical properties of deformed 3Y-TZP by scanning electron microscope (SEM). The indentation test showed that the mechanical properties of the specimens were reduced to about 1/2 by 30% deformation and to about 1/4 by 150% deformation. The SEM images showed that average grain size and deviation of grain size of each specimen increased with increasing deformation. From both the results, it was analytically shown that the increasing of the grain size was thought to be one of the causes of the reduction of the mechanical properties. (author)

  10. Coriolis mixing of the octupole vibrational bands in 156Gd

    Coriolis mixing of negative parity states in 156Gd nucleus is considered within the framework of a phenomenological model. Energy spectrum and ratios of effective probabilities of E1-transitions from the levels of octupole bands are described. Possibilities of E1-transitions from Kπ=2--band states are discussed; intraband E2-transitions in Kπ=0--, 1-- and 2--bands are calculated. 16 refs., 2 figs., 4 tabs

  11. Octupole strength in the neutron-rich calcium isotopes

    Riley, L A; Agiorgousis, M L; Baugher, T R; Bazin, D; Bowry, M; Cottle, P D; DeVone, F G; Gade, A; Glowacki, M T; Gregory, S D; Haldeman, E B; Kemper, K W; Lunderberg, E; Noji, S; Recchia, F; Sadler, B V; Scott, M; Weisshaar, D; Zegers, R G T

    2016-01-01

    Low-lying excited states of the neutron-rich calcium isotopes $^{48-52}$Ca have been studied via $\\gamma$-ray spectroscopy following inverse-kinematics proton scattering on a liquid hydrogen target using the GRETINA $\\gamma$-ray tracking array. The energies and strengths of the octupole states in these isotopes are remarkably constant, indicating that these states are dominated by proton excitations.

  12. Estimating the mechanical properties of the brittle deformation zones at Olkiluoto

    In rock mechanics modelling to support repository design and safety assessment for the Olkiluoto site, it is necessary to obtain the relevant rock mechanics parameters, these being an essential pre-requisite for the modelling. The parameters include the rock stress state, the properties of the intact rock and the rock mass, and the properties of the brittle deformation zones which represent major discontinuities in the rock mass continuum. However, because of the size and irregularity of the brittle deformation zones, it is not easy to estimate their mechanical properties, i.e. their deformation and strength properties. Following Section 1 explaining the motivation for the work and the objective of the Report, in Sections 2 and 3, the types of fractures and brittle deformation zones that can be encountered are described with an indication of the mechanisms that lead to complex structures. The geology at Olkiluoto is then summarized in Section 4 within the context of this Report. The practical aspects of encountering the brittle deformation zones in outcrops, drillholes and excavations are described in Sections 5 and 6 with illustrative examples of drillhole core intersections in Section 7. The various theoretical, numerical and practical methods for estimating the mechanical properties of the brittle deformation zones are described in Section 8, together with a Table summarizing each method's advantages, disadvantages and utility in estimating the mechanical properties of the zones. We emphasise that the optimal approach to estimating the mechanical properties of the brittle deformation zones cannot be determined without a good knowledge, not only of each estimation method's capabilities and idiosyncrasies, but also of the structural geology background and the specific nature of the brittle deformation zones being characterized. Finally, in Section 9, a Table is presented outlining each method's applicability to the Olkiluoto site. A flowchart is included to indicate the proposed structure for a brittle deformation zone mechanical property estimation campaign, noting that the exact nature of future work will depend on the results of the ONKALO Prediction-Outcome studies and decisions on the rock mechanics work required to support the repository design. (orig.)

  13. Structure property correlation: electrochemomechanical deformation in polypyrrole films

    Direct electrochemomechanical deformation (ECMD) behavior in the electrodeposited freestanding films of polypyrrole (PPy) doped with naphthalene sulphonic acid (NSA) has been investigated using cyclic voltammetry and cyclic step-voltammetry. It has been found that NSA doped PPy exhibits different film morphology when it was electrodeposited on to the different substrates such as non-corrosive stainless steel, indium-tin-oxide glass and platinum being used as anode. The differential behavior in ECMD characteristics observed on PPy film deposited on different substrates are associated with differential microstructures and porosities of the film as evidenced by scanning electron microscopic observations. An attempt has been made to correlate the effect of film morphology and the relative porosity of the film on the ECMD characteristics in the NSA doped PPy freestanding films

  14. Microstructure and local mechanical property evolution during high strain-rate deformation of tantalum

    Vachhani, Shraddha J.; Mara, Nathan; Livescu, Veronica; Cerreta, Ellen

    2015-09-01

    Shear localization is often a failure mechanism in materials subjected to high strain rate deformation. It is generally accepted that the microstructure evolution during deformation and the resulting heterogeneities strongly influence the development of these shear bands. Information regarding the development of local mechanical heterogeneities during deformation is difficult to characterize and as such, constitute is a critical missing piece in current crystal plasticity models. With the recent advances in spherical nanoindentation data analysis, there is now an unprecedented opportunity to obtain insights into the change in local mechanical properties during deformation in materials at sub-micron length scales. In this work, we quantify the evolution of microstructure and local mechanical properties in tantalum under dynamic loading conditions (split Hopkinson pressure bar), to capture the structure- property correlations at the sub-micron length scale. Relevant information is obtained by combining local mechanical property information captured using spherical nanoindentation with complimentary structure information at the indentation site measured using EBSD. The aim is to gain insight into the role of these microstructural features during macroscopic deformation, particularly their influence on the development of mechanical heterogeneities that lead to failure.

  15. Microstructure, texture and mechanical properties of cyclic expansion–extrusion deformed pure copper

    A recently developed severe plastic deformation technique, cyclic expansion–extrusion (CEE), was applied on a commercial pure copper to investigate the relationship between microstructure, texture and mechanical properties over a wide range of strains. Microstructure and crystallographic texture investigations were performed by optical microscopy, electron back scattering and X-ray diffraction. Significant evolution in grain refinement was achieved down to sub-micron grain size. A considerable texture evolution was also observed within the deformation zone with the extrusion as the decisive step for the final texture. Fiber deformation textures were observed; the 〈111〉 component was found to be the main texture component while the 〈100〉 component became significant only at very large strains. The evolution in hardness and tensile properties was studied and a clear relationship between texture evolution, microstructural parameters and mechanical properties was found and discussed

  16. Alignment of the K = 2- octupole and ground-band angular momenta in 180W

    Excitation of the K = 2- octupole band up to the 14- member in the reaction 181Ta(p, 2n?)180W shows an odd-even energy staggering. This staggering can be interpreted in terms of different Coriolis-induced alignments of the rotational and octupole vibrational angular momenta for the odd- and even-spin members of the K = 2- octupole band. There is no evidence that the K = 2- octupole vibration decomposes into two-quasiparticle decoupled states even at the highest spins observed

  17. Tuning of a deformable image registration procedure for skin component mechanical properties assessment.

    Montin, E; Cutri, E; Spadola, G; Testori, A; Pennati, G; Mainardi, L

    2015-08-01

    Several studies report the mechanical properties of skin tissues but their values largely depend on the measurement method. Therefore, we investigated the feasibility of recognizing the cellular constituents mechanical properties of pigmented skin by Confocal Laser Scanner Microscopy (CLSM). With this purpose, an healthy volunteer was examined in three areas nearby a pigmented skin lesion in two configurations: deforming and non deforming the nevus. The tissue displacement of the nevus was then assessed by means of deformable registration of the images in these two configurations. There are several registration strategy able to overcome this task, among them, we proposed two methods with different deformation models: a Free Form Deformation (FFD) model based on b-spline and a second one based on Demons Registration Algorithm (DRA). These two strategies need the definition of several parameters in order to obtain optimal registration performances. Thus, we tuned these parameters by means of simulated data and evaluated their registration abilities on the real in vivo CLSM acquisitions in the two configurations. The results showed that the registration using DRA had a better performance in comparison to the FFD one, in particular in two out of the three areas the DRA performance was significantly better than the FFD one. The registration procedure highlighted deformation differences among the chosen areas. PMID:26737734

  18. Petrophysical properties of deformation bands and their influence on fluid flow in carbonate grainstones: insights from the Maghlaq Fault, Malta.

    Fossmark, Heidi Synnøve Solli

    2015-01-01

    Deformation bands are tabular, sub- centimeter thick zones, which accommodates shear and/or volumetric deformation. Only a few examples of deformation bands have been documented in porous carbonate rocks, and the knowledge about how petrophysical properties and fluid flow interacts in such settings is thus limited. Motivated by this, the current study focus on deformation bands found in carbonate grainstones in the hangingwall of an extensional fault on the southwestern c...

  19. Homogenized Elastic Properties of Graphene for Small Deformations

    Jurica Sorić

    2013-09-01

    Full Text Available In this paper, we provide the quantification of the linear and non-linear elastic mechanical properties of graphene based upon the judicious combination of molecular mechanics simulation results and homogenization methods. We clarify the influence on computed results by the main model features, such as specimen size, chirality of microstructure, the effect of chosen boundary conditions (imposed displacement versus force and the corresponding plane stress transformation. The proposed approach is capable of explaining the scatter of the results for computed stresses, energy and stiffness and provides the bounds on graphene elastic properties, which are quite important in modeling and simulation of the virtual experiments on graphene-based devices.

  20. gamma-ray spectroscopic study of calcium-48,49 and scandium-50 focusing on low lying octupole vibration excitations

    McPherson, David M.

    An inverse kinematic proton scattering experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) using the GRETINA-S800 detector system in conjunction with the Ursinus College liquid hydrogen target. gamma-ray yields from the experiment were determined using geant4 simulations, generating state population cross sections. These cross sections were used to extract the delta_3 deformation length for the low-lying octupole vibration excitations in Ca-48,49 using the coupled channels analysis code fresco. Particle-core coupling in Ca-49 was studied in comparison to Ca-48 through determination of the neutron and proton deformation lengths. The total inverse kinematic proton scattering deformation lengths were evaluated for the low-lying octupole vibration excitations in Ca-48,49 to be delta_3(Ca-48, 3. -_1) = 1.0(2)fm,delta_3(Ca-49, 9/2. +_1) = 1.2(1)fm, delta_3 (Ca-49, 9/2. +_1) = 1.5(2)fm, delta_3(Ca-49,5/2. +_1) = 1.1(1)fm. Proton and neutron deformation lengths for two of theseoctupole states were also determined to be delta_p(Ca-48, 3. -_1) = 0.9(1)fm,delta_p (Ca-49, 9/2. +_1) = 1.0(1)fm, delta_n(Ca-48, 3. -_1) = 1.1(3)fm, anddelta_n(Ca-49, 9/2. +_1) = 1.3(3)fm. Additionally, the ratios of the neutronto proton transition matrix elements were also determined for these two states to be M_n/M_p(Ca-48, 3. -_1) = 1.7(6) and M_n/M_p(Ca-49, 9/2. +_1) = 2.0(5).Statistically, the derived values for these two nuclei are nearly identical.

  1. Red Blood Cell Deformation Under Shear Flow: The Effect of Changing Cell Properties

    Forsyth, Alison M.; Wan, Jiandi; Ristenpart, William D.; Stone, Howard A.

    2008-11-01

    The deformability of red blood cells plays a major role in the pathology of several diseases, including malaria, sickle cell anemia and spherocytosis. Moreover, deformations are believed to trigger the release of adenosine triphosphate, which helps regulate vascular tone and is consequently an important factor in various vascular diseases. Here we investigate single-cell viscoelastic responses to increased shear stress in poly(dimethylsiloxane) channels with a single constriction 2-4 times larger than a typical erythrocyte. These channels mimic arteriole-sized vessels, and have the advantage that the cell membrane is not in contact with the channel walls which have vastly different mechanical and material properties than living tissue. High-speed video and image analysis were used to quantify the trajectories and deformations of cells exposed to varied doses of diamide, a chemical known to ``rigidify'' erythrocytes. Our results show that (i) deformation is proportional to shear rate and (ii) the deformability of diamide-treated cells is greater than that of untreated cells. The latter is an unforeseen result because micropipette aspiration experiments have shown the opposite. We expect that the experimental procedure described here will be useful for characterizing the effect of different therapeutic agents on cellular deformability.

  2. Self-similarity properties of nafionized and filtered water and deformed coherent states

    Capolupo, A; Elia, V; Germano, R; Napoli, E; Niccoli, M; Tedeschi, A; Vitiello, G

    2013-01-01

    By resorting to measurements of physically characterizing observables of water samples perturbed by the presence of Nafion and by iterative filtration processes, we discuss their scale free, self-similar fractal properties. By use of algebraic methods the isomorphism is proved between such self-similarity features and the deformed coherent state formalism.

  3. Optical properties of plastically deformed copper: an ellipsometric study: Opti?ne lastnosti plasti?no derformiranega bakra: tudij elipsometrije:

    Anel, Ivan; Hadi?, Branka; Rom?evi?, Maja J.; Rom?evi?, Neboja; Rudolf, Rebeka; Traji?, Jelena; Vasiljevi?-Radovi?, Dana

    2011-01-01

    In this paper the results of optical properties investigations on plastically deformed copper are presented. The optical properties of the plastically deformed copper were studied using spectroscopic ellipsometry in the ultraviolet-visible (UV-VIS) range. Chemically pure copper was deformed by applying the Equal Channel Angular Pressing (ECAP) technique. During the last decade, equal-channel angular pressing procedure was used for the fabrication of ultrafine-grained metals and alloys. The pl...

  4. Ambipolar electric fields and turbulence studies in the Wisconsin levitated toroidal octupole

    Detailed studies of hot ion plasmas (T/sub i/ > T/sub e/) in the poloidal field octupole show that the ambipolar electric field which is perpendicular to the flux surfaces is well explained by the observed properties of the microturbulence structures in the plasma. The turbulence structure has been measured by correlation techniques which are carefully described. In these experiments, signals were studied which are aperiodic in time and space, short lived compared to the decay times of the bulk plasma parameters, short ranged compared to the machine size, and are therefore classified as microturbulence structures. The resulting spatial and temporal correlation functions (CFs) are well fitted to a Gaussian function and the associated correlation lengths or times are the half width at half maximum of the CFs. The correlation length is measured to be the ion gyro radius for the hot hydrogen plasma and somewhat less for the helium plasma

  5. Analysis of plastic properties of titanium alloys under severe deformation conditions in machining

    Alexander I. Khaimovich; Andrey V. Balaykin

    2014-01-01

    The present paper presents a method of analysis of titanium alloys plastic properties under severe deformation conditions during milling with registration of the cutting force components Fx, Fy, Fz in real time using a special stand. The obtained constitutive relations in the form the Johnson-Cook law for stresses and dependence for a friction coefficient describing the titanium alloy VT9 plastic properties under simulate operating conditions.

  6. Investigation of electromagnetic quadrupole-octupole lens with simplified construction

    On the basis of analytical expressions for distribution of potential one calculated numerically the trajectories of charged particle beams in a simplified electromagnetic quadrupole-octupole lens. One obtained the positions of focuses within space of image of that lens within wide range of initial condition changing. One determined ratios between electrostatic and magnetic constituents of a lens ensuring correction of chromatic aberrations for the beams remote from the axis that differed from those in the classical case. One calculated phase ellipses at lens outlet in case if beams occupying at the outlet the major part of aperture and determined the conditions of their transformation with most insignificant distortions

  7. High β studies in the Wisconsin Toroidal Octupole

    A wide range of MHD stable high β plasmas is produced in the Wisconsin Levitated Octupole. At or near the single fluid regime we obtain, in the bad curvature region, β = nk(T/sub e/ + T/sub i/)8π/B2 approx. = 8%, twice the theoretical single fluid ballooning instability limit of 4%. We also obtain stable plasmas at β approx. = 35%, 9 times the theoretical limit, in a regime in which both finite ion gyroradius and gyroviscosity effects are important

  8. Octupole correlation effects in 151Pm

    Excited states of 151Pm have been observed using the 150Nd(?,p2n) reaction at a beam energy of 35 MeV. Levels with spin up to 19/2 have been seen in a positive parity band built on the 5/2+ ground state, and up to 21/2 in a negative parity band built on the 5/2- level at 117 keV excitation energy. Levels of the same spin but opposite parity are nearly degenerate and there are strong (?1.1x10-3 W.u.) electric dipole transitions between members of the two bands. The energy staggering of levels and their electromagnetic decay properties are somewhat different for the two bands

  9. Deformation properties of highly plastic fissured Palaeogene clay - Lack of stress memory?

    Krogsbøll, Anette; Hededal, Ole; Foged, Niels Nielsen

    fissuring or debonding. Based on a large amount of high quality tests on Palaeogene clay partly encountered at Fehmarn Belt the typical deformational behaviour during unloading and swelling is discussed and evaluated with focus on stress states. K0-OCR relations are established and the relations are...... deformation properties, and to help explain the large primary and secondary swelling indices measured in Palaeogene clays and how they are related to preconsolidation stress. It is proven that the Palaeogene clay tends to “forget” the preconsolidation stress and the consequence is that OCR is not always a...

  10. Octupole Ordering Model for the Phase IV of CexLa1-xB6

    Kubo, K; Kubo, Katsunori; Kuramoto, Yoshio

    2003-01-01

    An octupole ordering model is studied by the mean field theory, and its relevance to the phase IV of CexLa1-xB6 is discussed. The observed lattice distortion along the [111] direction is interpreted in terms of the \\Gamma_{5g}-type ferro-quadrupole moment induced by an antiferro-octupole ordered state with \\Gamma_{5u} symmetry. The octupole model also accounts for the cusp in the magnetization as in the N\\'{e}el transition, and the softening of the elastic constant C_{44} below the ordering temperature. However, the internal magnetic field due to the octupole moment is smaller than the observed one by an order of magnitude. Also discussed is the possibility of a pressure induced antiferromagnetic moment in the octupole-ordered state.

  11. Symmetries and deformations in the spherical shell model

    Van Isacker, Piet

    2016-01-01

    We discuss symmetries of the spherical shell model that make contact with the geometric collective model of Bohr and Mottelson. The most celebrated symmetry of this kind is SU(3), which is the basis of Elliott's model of rotation. It corresponds to a deformed mean field induced by a quadrupole interaction in a single major oscillator shell N and can be generalized to include several major shells. As such, Elliott's SU(3) model establishes the link between the spherical shell model and the (quadrupole component of the) geometric collective model. We introduce the analogue symmetry induced by an octupole interaction in two major oscillator shells N-1 and N, leading to an octupole-deformed solution of the spherical shell model. We show that in the limit of large oscillator shells (large N) the algebraic octupole interaction tends to that of the geometric collective model.

  12. Symmetries and deformations in the spherical shell model

    Van Isacker, P.; Pittel, S.

    2016-02-01

    We discuss symmetries of the spherical shell model that make contact with the geometric collective model of Bohr and Mottelson. The most celebrated symmetry of this kind is SU(3), which is the basis of Elliotts model of rotation. It corresponds to a deformed mean field induced by a quadrupole interaction in a single major oscillator shell N and can be generalized to include several major shells. As such, Elliotts SU(3) model establishes the link between the spherical shell model and the (quadrupole component of the) geometric collective model. We introduce the analogue symmetry induced by an octupole interaction in two major oscillator shells N-1 and N, leading to an octupole-deformed solution of the spherical shell model. We show that in the limit of large oscillator shells, N\\to ? , the algebraic octupole interaction tends to that of the geometric collective model.

  13. Mechanical properties and microstructure of resistance spot welded severely deformed low carbon steel

    Highlights: → Resistance spot welding is successfully used for severely deformed steel sheet. → Microstructures of FZ and HAZ are refined to lower sizes at higher pass number. → Mechanical properties in FZ and HAZ are increased with increasing the pass number. → Electrode dip and nugget diameter are increased with increasing the pass number. - Abstract: The welding of nanostructured low carbon steel sheets produced by severe plastic deformation (SPD) has been considered in the present paper. Constrained groove pressing (CGP) method is used for imposing the severe plastic deformation to the steel sheets as a large pre-strain. The SPDed sheets are joined using resistance spot welding (RSW) process. The results show that severe plastic deformation can effectively increase the electrical resistivity of steel sheets; therefore it can affect the microstructure and mechanical properties of spot welds. Microstructure and mechanical properties of fusion zone, heat affected zone (HAZ), recrystallized zone and base metal of SPDed sheets are investigated and the results are compared with those of as-received specimens. The results show that with increasing the large pre-strain in sheets, at constant welding parameters (welding current and time), the fusion zone size, electrode indentation and nugget diameter are increased. Thus, peak load and hardness in fusion zone and HAZ are increased with increasing the CGP pass number. Also, the microstructures of fusion zone and HAZ are refined to lower sizes for larger pre-strained specimens.

  14. Determination of the B(E3, 0+ → 3-) strength in the strongly octupole correlated nucleus 224Ra using Coulomb excitation at REX-ISOLDE

    Exploiting the unique capabilities of REX-ISOLDE to provide intense post-accelerated 224Ra radioactive ion beams we were able to Coulomb excite low-lying, low-spin levels of 224Ra. The previously accessible observables, such as the excitation energies of negative parity levels, and theoretical calculations using various models locate this nucleus to be situated in a mass-region with enhanced octupole correlations. Our collaboration was for the first time capable to Coulomb excite opposite parity levels in a post-accelerated radioactive nucleus. Indeed, apart from quasi-stable Uranium isotopes, 224Ra is the so far heaviest post-accelerated nucleus ever. A first, preliminary, B(E3, 0+ → 3-) value provides quantitative information about the octupole correlations in this nucleus. The results will be discussed within the context of a possible stable octupole deformation in the ground state of this nucleus. An observation, that is implicating a CP-violating nuclear Schiff moment. The latter has a strong impact on the search for CP-violating physics in the atomic system of the neighbouring odd-mass Ra-isotopes. Financial support by the BMBF under grant 06DA9036I, HIC for FAIR and the ENSAR programme is gratefully acknowledged.

  15. The change in microstructure and mechanical properties on hot torsional deformation of BT9 titanium alloy

    The influence of temperature, strain rate and percentage reduction on mechanical properties and laminated microstructure evolution is studied for a two-phase titanium alloy VT9 (Ti-6.5Al-3.5Mo-1.6Zr-0.27Si) under hot deformation by torsion. It is revealed that the nature of the change of yield stresses under deformation as well as the margin of plasticity are conditioned by microcrystalline structure formation and are determined not only by temperature and strain rate conditions but also by specific features of torsional deformation. The degree of structural transformation is shown to be considerably lower under torsion compared to tension in spite of a higher level of residual strain

  16. Structure and mechanical properties of austenitic steel during linear and plane-strain low temperature deformation

    The structure and the properties of Kh18N10T steel depending on the kind of the stressed state during the low-temperature straining (at -160 deg C) were examined. It has been established that the intensity of the development of martensite transformation depends on the method of straining. When the linear stress passes over to the flat or plane stress, the resistance of steel to the plastic deformation increases. An analytical expression has been derived for the stress diagram for the strain hardening of austenite and for the resistance to deformation of the forming martensite. In the case of biaxial stretching, the martensite transformation is braked, the parameters of the deformation diagram vary, and the plasticity is decreased

  17. Mechanical properties of mammalian cells in suspension measured by electro-deformation

    We describe a planar, micro-fabricated device for generating fringing non-uniform electric fields. We used it to measure the mechanical properties of individual mammalian cells in suspension by deforming them in time-varying, non-uniform electric fields. Electrical stresses generated by the planar microelectrodes were used to trap and stretch cells, while cell deformation was observed using optical microscopy. Two distinct cell types were compared after fitting strain data with a three-parameter 'standard linear solid' model of visco-elasticity, and with a two-parameter power-law method. Chinese hamster ovary (CHO) cells were approximately twice as stiff as U937 human promonocytes, and CHO cells displayed an elastic behaviour with recovery of initial shape, while U937 strain data bore witness to plastic deformation. Our results demonstrate that electrical stresses generated by micro-fabricated electrodes permit mechanical characterization of distinct mammalian cell types.

  18. Influence of deformation ageing treatment on microstructure and properties of aluminum alloy 2618

    The effects of deformation ageing treatment (DAT) on the microstructure and properties of aluminum alloy 2618 were investigated. The alloy was subjected to deformation ageing treatment which included solution treating at 535 deg. C quenching into water at room-temperature, cold rolling (10%) and further ageing to peak hardness level at 200 deg. C. The electron microscopic studies revealed that the treatment affects the ageing characteristics and the coarsening of ageing phase (S') at elevated-temperature. The dislocation-precipitate tangles substructure couldn't be found in alloy 2618. The tensile and hardness tests showed that deformation-ageing treatment causes a significant improvement in tensile strength and hardness to alloy 2618 at room- and elevated-temperature

  19. Microstructure, Properties and Atomic Level Strain in Severely Deformed Rare Metal Niobium

    Mart SAARNA

    2012-12-01

    Full Text Available The mechanical and physical properties relationship from atomic level strain/stress causes dislocation density and electrical conductivity relationship, as well as crystallites deformation and hkl-parameter change in the severely deformed pure refractory rare metal Nb at ambient temperature and during short processing times. The above mentioned issues are discussed in this study. For ultrafine-grained and nanocrystalline microstructure forming in metal the equal-channel angular pressing and hard cyclic viscoplastic deformation were used. The flat deformation and heat treatment at different parameters were conducted as follows. The focused ion beam method was used for micrometric measures samples manufacturied under nanocrystalline microstructure study by transmission electron microscope. The microstructure features of metal were studied under different orientations by X-ray diffraction scattering method, and according to the atomic level strains, dislocation density, hkl-parameters and crystallite sizes were calculated by different computation methods. According to results the evolutions of atomic level strains/stresses, induced by processing features have great influence on the microstructure and advanced properties forming in pure Nb. Due to cumulative strain increase the tensile stress and hardness were increased significantly. In this case the dislocation density of Nb varies from 5.0E+10 cm–2 to 2.0E+11 cm–2. The samples from Nb at maximal atomic level strain in the (110 and (211 directions have the maximal values of hkl-parameters, highest tensile strength and hardness but minimal electrical conductivity. The crystallite size was minimal and relative atomic level strain maximal in (211 orientation of crystal. Next, flat deformation and heat treatment increase the atomic level parameters of severely deformed metal.DOI: http://dx.doi.org/10.5755/j01.ms.18.4.3091

  20. Effect of viscosity of petroleum products on deformation properties of concrete

    A.P. Svintsov

    2014-11-01

    Full Text Available This paper presents the results of studies of the effect of petroleum products, impregnating in concrete, on its deformation properties. Petroleum products, impregnating in concrete and reinforced concrete structures, have a negative impact on their strength and deformation characteristics. The negative impact of petroleum products on concrete and reinforced concrete is associated with changes in the hydration process of cement, as well as changes in the structure of the concrete. Strength and deformation characteristics of concrete change due to hydraulic pressure of petroleum products in the pores exerted on the skeleton of cement stone. In this aspect, the crucial point is the porosity of concrete as a permeability factor for petroleum products. One of the most important factors affecting the physical and mechanical characteristics of oil-impregnated concrete is their viscosity. In this paper, the mathematical description of the change of deformation depending on the relative viscosity of impregnating of petroleum products, the value of the axial load and the concrete class was proposed. The obtained results allow assessing changes in deformation characteristics of load-bearing concrete and reinforced concrete of industrial buildings, where petroleum products are used in the technological processes.

  1. Effects of recrystallization on texture, microstructure and mechanical properties in HPT-deformed pure Mg

    Bonarski, Bartlomiej J; Schafler, Erhard; Zehetbauer, Michael J [Research Group Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria); Mikulowski, Borys, E-mail: bartlomiej.bonarski@univie.ac.a [Department of Metallic Materials and Nanotechnology, Faculty of Non-Ferrous Metals, AGH - University of Science and Technology, Al. Mickiewicza 30/A-2, PL-30059 Krakow (Poland)

    2010-07-01

    Mg of purity 99.8 wt% was deformed by High Pressure-Torsion at hydrostatic pressures 1 to 4 GPa and RT, up to plastic shear strains of 120. X-ray texture analysis showed up deviations from expected shear texture, which increased with increasing shear strain and hydrostatic pressure. According to TEM and SEM investigations these deviations can be understood in terms of recrystallization. The current paper aimed at the differences of the recrystallization processes which occur during HPT deformation and unloading (dynamic recrystallization, DRX), and those after deformation (static recrystallization, SRX). For this purpose, two sorts of samples were investigated: (i) such being stored at RT immediately after HPT deformation, and (ii) such being stored at 77 K immediately after HPT deformation, and stored at RT for a minimum and constant time needed for preparation. The results show that SRX brings the texture closer to the ideal shear texture and to higher strength values, but to smaller ductilities than DRX does. The mechanical properties can be attributed to changes of texture rather than to those of grain size.

  2. Changes in structure and properties of austenitic steel during hot deformation

    The changes of structure and properties of the 12Kh18N10T steel have been studied during hot deformation by tension. Property changes have been judged by the form of the s-n diagram curve in the true-stress-true strain coordinates. Structure has been studied by the methods of optical and electron microscopy. It is shown that the initial stages of hardening of the hot-deformed austenite (epsilon = 20-25% is the development of the dynamic recrystallization which occurs by the way of subgrain coalescence. The increased dislocation density in recrystallized volumes and the formation of new mean- and high angular boundaries provides the summary hardening of austenite, in spite of the development of dynamic recrystallization processes

  3. Electrical textile sensors for repeated large deformation: structures and electromechanical properties

    Tao, Xiaoming

    2008-11-01

    This paper presents a systematic study of various fibrous structures that exhibit excellent strain/force sensing properties for repeated large deformation (up to 50% or more). The multiple-scaled investigation has been conducted with fibers, yarns and fabrics made from intrinsic electrically conductive materials or coated with conductive polymers or composites. The structures and electrical conductivity of these fibrous assemblies during large deformation have been characterized by various experimental techniques. Several challenges of using textiles as strain sensors and solutions to various problems are discussed. A theoretical analysis of knitted fabric strain sensors is presented to link the fiber properties and fabric structure with the electrical conductivity of the sensors as a function of strain/force.

  4. Aluminium. II - A review of deformation properties of high purity aluminium and dilute aluminium alloys.

    Reed, R. P.

    1972-01-01

    The elastic and plastic deformation behavior of high-purity aluminum and of dilute aluminum alloys is reviewed. Reliable property data, including elastic moduli, elastic coefficients, tensile, creep, fatigue, hardness, and impact are presented. Single crystal tensile results are discussed. Rather comprehensive reference lists, containing publications of the past 20 years, are included for each of the above categories. Defect structures and mechanisms responsible for mechanical behavior are presented. Strengthening techniques (alloys, cold work, irradiation, quenching, composites) and recovery are briefly reviewed.

  5. Processing of ultrafine-grained materials using severe plastic deformation: potential for achieving exceptional properties

    Langdon, T.G.

    2008-01-01

    The processing of polycrystalline metals through the application of severe plastic deformation is attracting much attention because of the potential for achieving significant grain refinement to the submicrometer or nanometer level. This paper reviews the principles of this type of processing with emphasis on two different techniques: Equal- Channel Angular Pressing and High-Pressure Torsion. Exceptional properties may be achieved from these processes including high strength at ambient temper...

  6. Microstructure and Local Mechanical Properties of Cu-Co Alloys after Severe Plastic Deformation

    Buršík, Jiří; Buršíková, V.; Svoboda, Milan; Král, Petr; Dvořák, Jiří; Sklenička, Václav

    Zurich : Trans Tech Publications, 2014 - (Pešek, L.; Zubko, P.), s. 100-103 ISBN 978-3-03785-876-9. ISSN 1013-9826. - (Key Engineering Materials. 586). [LMP 2012 International Conference on Local Mechanical Properties /9./. Levoča (SK), 07.11.2012-09.11.2012] R&D Projects: GA ČR(CZ) GAP108/11/2260 Institutional support: RVO:68081723 Keywords : severe plastic deformation * electron microscopy * EBSD Subject RIV: JG - Metallurgy

  7. Octupole correlations in neutron-rich 143,145Ba and a type of superdeformed band in 145Ba

    High spin states in neutron-rich odd-Z 143,145Ba nuclei have been investigated from the study of prompt ? rays in the spontaneous fission of 252Cf by using ?-?- and ?-?-?- coincidence techniques. Alternating parity bands are identified for the first time in 145Ba and extended in 143Ba. A new side band, with equal, constant dynamic, and kinetic moments of inertia equal to the rigid body value, as found in superdeformed bands, is discovered in 145Ba. Enhanced E1 transitions between the negative- and positive-parity bands in these nuclei give evidence for strong octupole deformation in 143Ba and in 145Ba. These collective bands show competition and coexistence between symmetric and asymmetric shapes in 145Ba. Evidence is found for crossing M1 and E1 transitions between the s=+i and s=-i doublets in 143Ba. copyright 1999 The American Physical Society

  8. Structural and mechanical properties of nanocrystalline titanium processed by severe plastic deformation

    Popov, A.A.; Pyshmintsev, I.Y.; Demakov, S.L.; Illarionov, A.G. [Ural State Technical Univ., Ekaterinburg (Russian Federation); Lowe, T.C. [Los Alamos National Lab., NM (United States); Sergeyeva, A.V.; Valiev, R.Z. [Ufa State Aviation Technical Univ. (Russian Federation). Inst. of Advanced Materials Physics

    1997-10-01

    Recent investigations have demonstrated that materials with ultrafine grain (UFG) structure (nano- and submicron crystalline) can be processed by severe plastic deformation. One advantage of this method is that it can be applied to both pure metals and alloys. Moreover, it produces samples that have no residual porosity so that meaningful measurements of the physical and mechanical properties are possible. Investigations of ultrafine grain copper and aluminum alloys have revealed a number of specific features of their mechanical behavior, namely extremely high hardness and strength, the absence of strain hardening, and deviation form the Hall-Petch relationship. In this work the authors investigate the mechanical properties and thermal stability of UFG titanium.

  9. Experiment and analysis on elastic deformation properties of graphite and carbon materials for HTTR core components

    Fine-grained isotropic graphite grade IG-110, medium-grained near-isotropic graphite grade PGX and coarse-grained baked carbon grade ASR-ORB are employed as structural materials for the High Temperature Engineering Test Reactor (HTTR). The material properties for design are specified in Structural Design Code for Graphite Components of HTTR. This report describes in detail the experiment on deformation behavior including stress-strain relationship, elastic modulas and Poisson's ratio of each grade. An analytical method for linear elastic approximation leads to the property values contained in the Code. (author)

  10. Effect of thermomechanical conditions of deformation on structure and properties of tungsten wire

    The purpose of the investigation is to specify the relation between conditions of plastic deformation of non-slacked tungsten, structure and properties of rods and wire. Planning multifactor experiments is chosen as the basic method for investigation. It is shown that rationai choice of plastic working conditions permits to reduce the tendency to lamination of tungsten wire. Growth of wire ductility is followed by decrease of its residual electroresistance. Rapid porocedure of return due to precipitation of dissolved admixtures is the main reason for improving plastic properties of the wire

  11. Plasma resistivity measurements in the Wisconsin levitated octupole

    Resistivity measurements parallel to the magnetic field were made on gun injected plasmas ranging in density from 109cm-3 to 101parallelcm-3 in the Wisconsin levitated octupole with toroidal and poloidal magnetic fields. The 109cm-3 plasma was collisionless with lambda/sub mfp/ > 100 mirror lengths, had T/sub e/ = 10 eV, T/sub i/ = 30 eV and was found to have anomalous resistivity scaling like eta = √T/sub e//n/sub e/ when E/sub parallel/ > E/su c/ is the Dreicer critical field. The 1012cm-3 plasma was collisional with lambda/sub mfp/ < mirror length, had T/sub e/ = T/sub i/ approx. = .2 eV and was found to have Spitzer resistivity when E/sub parallel/ < E/sub c/

  12. Plasma resistivity measurements in the Wisconsin levitated octupole

    Brouchous, D. A.

    1980-11-01

    Resistivity measurements parallel to the magnetic field were made on gun injected plasmas ranging in density from 10/sup 9/cm/sup -3/ to 10/sup 1/parallelcm/sup -3/ in the Wisconsin levitated octupole with toroidal and poloidal magnetic fields. The 10/sup 9/cm/sup -3/ plasma was collisionless with lambda/sub mfp/ > 100 mirror lengths, had T/sub e/ = 10 eV, T/sub i/ = 30 eV and was found to have anomalous resistivity scaling like eta = ..sqrt..T/sub e//n/sub e/ when E/sub parallel/ > E/su c/ is the Dreicer critical field. The 10/sup 12/cm/sup -3/ plasma was collisional with lambda/sub mfp/ < mirror length, had T/sub e/ = T/sub i/ approx. = .2 eV and was found to have Spitzer resistivity when E/sub parallel/ < E/sub c/.

  13. Prediction of Thermal and Elastic Properties of Honeycomb Sandwich Plate for Analysis of Thermal Deformation

    Thermal problems that are directly related to the lifetime of an electronic device are becoming increasingly important owing to the miniaturization of electronic devices. To solve thermal problems, it is essential to study thermal stability through thermal diffusion and insulation. A honeycomb sandwich plate has anisotropic thermal conductivity. To analyze the thermal deformation and temperature distribution of a system that employs a honeycomb sandwich plate, the thermal and elastic properties need to be determined. In this study, the thermal and elastic properties of a honeycomb sandwich plate, such as thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and shear modulus, are predicted. The properties of a honeycomb sandwich plate vary according to the hexagon size, thickness, and material properties

  14. Structure and properties of Fe-36% Ni alloy after heavy shear deformation

    A study was made into the influence of large shear strain by pressing on structure, mechanical and thermal properties of the Fe-36% Ni invar. The first pressing pass (70% reduction) is shown to result in formation of strip structure. An increase of the number of passes with changing shear deformation direction for reverse one at every even pressing p[ass promotes strip structure transformation into fragmented one. Yield strength of the alloy increases from 300 to 650 N/mm2 after the first pass. After 12 passes at attains the value of 800 N/mm2 due to strain hardening. A linear thermal expansion coefficient varies nonmonotonously with deformation, and after 12 passes preserves a permissible value. 17 refs., 10 figs

  15. Theoretical study on effect of radial and axial deformation on electron transport properties in a semiconducting Si–C nanotube

    Sudhanshu Choudhary; S Qureshi

    2012-10-01

    We investigate electron transport properties in a deformed (8, 0) silicon carbide nanotube by applying self consistent non-equilibrium Green’s function formalism in combination with the density-functional theory to a two-probe molecular junction constructed from deformed nanotube. The results suggest significant reduction in threshold voltage in the case of both radially compressed and axially elongated (8, 0) SiCNTs, a large difference in current–voltage characteristics was observed. Analysis of frontier molecular orbitals (FMO) and transmission spectrum show bandgap reduction in deformed nanotubes. Deformation introduces electronic states near the Fermi level, enhancing the conduction properties of (8, 0) SiCNT. The FMOs and the orbitals corresponding to peaks in () around Fermi level obviously has some major contributions from the deformed site. However, localization of the electronic state near the Fermi level is weak in (8, 0) SiCNT, possibly because of its large bandgap.

  16. Deformation properties of osmium, platinum, mercury isotopes from self-consistent calculations: influence of the pairing treatment

    The deformation properties of several isotopes of the elements Os, Pt and Hg have been computed by means of Hartree-Fock plus BCS calculations. The Hartree-Fock potential has been derived from the Skyrme interaction S III. Two approximations have been used for the treatment of pairing correlations: the constant (versus deformation) gap method and the constant (versus deformation) pairing matrix element method. A good agreement with experimental data is obtained for ground state deformation properties except for the exact location of the prolate-oblate transition as a function of the neutron number. For one nucleus 184Hg, the pairing matrix elements have been calculated from the Gogny interaction D1, in order to study their single particle state- and deformation-dependence. From these results, the validity of the two approximations used for pairing correlations, is discussed

  17. Electric octupole contribution to the angular distribution of the krypton 4p photoelectrons

    The angular distribution of Kr 4p photoelectrons was measured with linearly polarized synchrotron radiation in the function of the photon energy. The shape of the measured angular distributions indicates the presence of octupol interaction.

  18. Octupole transitions in the /sup 92/Mo(. pi. /sup + -/,. pi. /sup + -/) reactions

    Doss, K.G.R.; Eisenstein, R.A.; Wharton, W.R.; Blanpied, G.; Burleson, G.R.; Amann, J.F.

    1979-07-15

    The /sup 92/Mo(..pi../sup + -/,..pi../sup + -/) reactions at T/sub ..pi../=180 MeV populating octupole states are examined to suggest the (..pi..,..pi..') reaction as an interesting probe of nuclear structure.

  19. Optimisation by plastic deformation of structural and mechanical uranium alloys properties

    Structural and mechanical properties evolution of rich and poor uranium alloys are investigated. Good usual properties are obtained with few metallic additions with a limited effect giving a fine and isotrope grain structure. Amelioration is observed with heat treatment from ? and ? phases high temperature range. However, dynamic recrystallisation, related to hot working, is the better phenomena to maximize the usual mechanical and structural properties. So high temperature behaviour of rich and poor uranium alloys in ?, ? and ? crystalline structure is studied: - dynamic recrystallisation phenomena begins only in ?, and ? phases high temperature range; - high strength and brittle ? phase shows a very large ductility above 700 deg C. Recrystallisation is a thermal actived phenomena localised at grain boundary, dependant with alloys concentration and crystalline structure. ? phase activation energy and deformation rate for dynamic recrystallisation beginning are most important, than ? and ? phases in relation with quadratic structure complexity. Both temperature and deformation rate are the main dynamic recrystallisation factors. Optimal usual mechanical and structural properties obtained by hot working (forging, milling) are sensible to hydrogen embrittlement

  20. Octupole correlations in the nucleus $^{144}$Ba described with symmetry conserving configuration mixing calculations

    Bernard, Rémi N; Rodríguez, Tomás R

    2016-01-01

    We study the interplay of quadrupole and octupole degrees of freedom in the structure of the isotope $^{144}$Ba. A symmetry conserving configuration mixing method (SCCM) based on a Gogny energy density functional (EDF) has been used. The method includes particle number, parity and angular momentum restoration as well as axial quadrupole and octupole shape mixing within the generator coordinate method. Predictions both for excitation energies and electromagnetic transition probabilities are in good agreement with the most recent experimental data.

  1. Mixed-symmetry octupole and hexadecapole excitations in the N=52 isotones

    Hennig, A.; Spieker, M.(Institute for Nuclear Physics, University of Cologne, Zlpicher Strae 77, Cologne, D-50937, Germany); Werner, V.; Ahn, T; Anagnostatou, V.; Cooper, N.; Derya, V.; Elvers, M.; Endres, J.; Goddard, P.; Heinz, A.; Huges, R. O.; Ilie, G.; Mineva, M. N.; Petkov, P.

    2015-01-01

    Background: Excitations with mixed proton-neutron symmetry have been previously observed in the $N=52$ isotones. Besides the well established quadrupole mixed-symmetry states (MSS), octupole and hexadecapole MSS have been recently proposed for the nuclei $^{92}$Zr and $^{94}$Mo. Purpose: The heaviest stable $N=52$ isotone $^{96}$Ru was investigated to study the evolution of octupole and hexadecapole MSS with increasing proton number. Methods: Two inelastic proton-scattering experiments on $^{...

  2. Application of Severe Plastic Deformation Techniques to Magnesium for Enhanced Hydrogen Sorption Properties

    Daniel Fruchart

    2012-08-01

    Full Text Available In this paper we review the latest developments in the use of severe plastic deformation (SPD techniques for enhancement of hydrogen sorption properties of magnesium and magnesium alloys. Main focus will be on two techniques: Equal Channel Angular Pressing (ECAP and Cold Rolling (CR. After a brief description of these two techniques we will discuss their effects on the texture and hydrogen sorption properties of magnesium alloys. In particular, the effect of the processing temperature in ECAP on texture will be demonstrated. We also show that ECAP and CR have produced different textures. Despite the scarcity of experimental results, the investigations up to now indicate that SPD techniques produce metal hydrides with enhanced hydrogen storage properties.

  3. Superplastic deformation effect on the structure and mechanical properties of titanium alloy VT9

    The structure and mechanical properties of the VT9 alloy after superplastic deformation (SPD) and serial treatment (ST), thermally treated after cooling in air according to two versions. It is shown that mechanical properties of VT9 alloy after treatment under SPD conditions is more homogeneous, and characteristics of plasticity, impact strength, rupture work and durability are higher than those after ST. As a result of SPD more homogeneous macro- and microstructure are formed in the alloy, the metastable β-phase decay is more uniform in different billet areas than that after ST. The features of ST and SPD effects on the structure and mechanical properties considered for VT9 alloy permit to substantiate these or those treatment conditions for two-phase titanium alloys

  4. Deformation, fracture, and mechanical properties of low-temperature-tempered martensite in SAE 43xx steels

    Saeglitz, M. [Deutsche Bahn AG, Brandenburg-Kirchmoeser (Germany); Krauss, G. [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgical and Materials Engineering

    1997-02-01

    Uniaxial tensile tests were performed on 4330, 4340, and 4350 steels in the as-quenched (AQ) condition and after quenching and tempering at 150 C, 175 C, and 200 C for times of 10 minutes, 1 hour, and 10 hours, respectively. Strength parameters decreased and ductility parameters increased continuously with increasing tempering. Mechanical properties are presented as a function of tempering conditions and steel carbon content, and hardness and ultimate strength changes are given as a function of Hollomon-Jaffe tempering parameters. All tempered specimens, except for some lightly tempered 4350 specimens, deformed plastically through necking instability and failed by ductile fracture. The stresses required for the ductile fracture, estimated from an analysis of the interfacial stresses at particles in the neck at fracture, showed no systematic variation with carbon content of tempering conditions despite significant variations in deformation and strain hardening. The AQ specimens of the 4340 and 4350 steels, and some of the lightly tempered 4350 steels, failed by brittle mechanisms. The deformation and fracture of the low-temperature-tempered 43xx steels are discussed in terms of the changes in fine structure, namely, the formation of transition carbides and a rearranged dislocation substructure that evolve from an AQ martensitic substructure consisting of dislocations with and without carbon atom segregation.

  5. Effect of cryogenic deformation on the structure and properties of chromium-nickel steels

    Glezer, A. M.; Rusanenko, V. V.; Zhukov, O. P.; Libman, M. A.; Klippenshtein, A. D.

    2012-10-01

    The effect of rolling at a temperature of 77 K and subsequent tempering on the structure and properties of chromium-nickel 05Kh14N14T2 and 15Kh14N14Yu1 steels is investigated. The formation of a nanocrystalline martensite phase in an austenitic matrix has been established. It is shown that additional hardening of the metal occurs due to the precipitation of intermetallic phases during heat treatment. The steels under study are high-strength and hard-magnetic after cryogenic deformation and heat treatment.

  6. Processing of metals by severe plastic deformation (SPD – structure and mechanical properties respond

    J. Zrnik

    2008-07-01

    Full Text Available SPD methods are used to convert coarse grain metals and alloys into ultrafine grained (UFG materials. Obtained UFG materials then possess improved mechanical and physical properties which destine them for a wide commercial use. This paper, in one direction, looks into historical development of SPD processes and their effect at obtaining fine crystalline structure, and on the other side also partially focuses on development of UFG structure and its stability in commercial pure aluminium as a function of strain and post-deformation annealing applied.

  7. Property optimization of nanostructured ARB-processed Al by post-process deformation

    Huang, Xiaoxu; Kamikawa, Naoya; Hansen, Niels

    The effect of post-process deformation on the mechanical properties of nanostructured aluminum (99.2% purity) has been investigated by cold rolling of samples which have been processed by accumulative roll bonding (ARB) to a strain of epsilon(vM) = 4.8. Samples have been cold rolled to 10, 15, and...... 50% reductions and ultimate tensile strength (UTS), yield stress and elongation have been determined by tensile testing at room temperature. The mechanical testing shows that cold rolling to low strains (10% and 15%) leads to softening and increase in elongation compared to the as-processed ARB...

  8. Processing of ultrafine-grained materials using severe plastic deformation: potential for achieving exception properties

    Langdon, T. G.

    2008-07-01

    The processing of polycrystalline metals through the application of severe plastic deformation is attracting much attention because of the potential for achieving significant grain refinement to the submicrometer or nanometer level. This paper reviews the principles of this type of processing with emphasis on two different techniques: Equal-Channel Angular Pressing and High-Pressure Torsion. Exceptional properties may be achieved from these processes including high strength at ambient temperatures and a rapid superplastic forming capability at elevated temperatures. Some examples are presented demonstrating the potential use of this type of processing. (Author) 53 refs.

  9. Change of mechanical properties of 1201 welding alloy under deformation and gamma-irradiation action

    The effect of #betta#-irradiation and strain on mechanical properties of the aged 1201 alloy has been studied. It has been shown that the 1201 aluminium alloy straining by a single-axis stretching with the deformation degree of epsilon=3-5% after quenching before artificial ageing leads to the 20-30% strength growth and to 1.5-2 times ductility growth. The process of #betta#-irradiation between strain and artificial ageing increases the alloy strength up to epsilon=9% within the high ductility. The above regularities are also true for welded joint metal

  10. Enhanced mechanical properties in a Zr-based metallic glass caused by deformation-induced nanocrystallization

    Bulk metallic glass with composition Zr62Cu18Ni10Al10 exhibits high yield stress, large elasticity and large plasticity when compressed. During nanoindentation, strain hardening is observed until the maximum applied load reaches 100 mN; for higher maximum loads the typical softening found in metallic glasses is evidenced. Transmission electron microscopy observation of the nanoindented and compressed samples reveals the occurrence of deformation-induced nanocrystallization, which is likely to be related to the mechanical properties observed in this alloy.

  11. Effects of deformation on the electronic properties of B-C-N nanotubes

    Azevedo, S., E-mail: sazevedo@fisica.ufpb.br [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58059-900 Joao Pessoa-PB (Brazil); Rosas, A. [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58059-900 Joao Pessoa-PB (Brazil); Machado, M. [Departamento de Fisica, Universidade Federal de Pelotas, Caixa Postal 354, 96010-900 Pelotas-RS (Brazil); Kaschny, J.R. [Instituto Federal da Bahia-Campus Vitoria da Conquista, Av. Amazonas 3150, 45030-220 Vitoria da Conquista-BA (Brazil); Chacham, H. [Departamento de Fisica, ICEX, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970 Belo Horizonte-MG (Brazil)

    2013-01-15

    We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC{sub 2}N and C-doped BNNTs. Four different types of BC{sub 2}N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. - Graphical Abstract: We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC{sub 2}N and C-doped BNNTs. Four different types of BC{sub 2}N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. Highlights: Black-Right-Pointing-Pointer We investigated electronic properties of flattened BC{sub 2}N nanotubes. Black-Right-Pointing-Pointer The electronic states depend strongly on compression. Black-Right-Pointing-Pointer It is studied flattened BN nanotubes doped with a carbon atom. Black-Right-Pointing-Pointer The flattened C-doped structures, presents a significant reduction of the gap.

  12. Effects of deformation on the electronic properties of BCN nanotubes

    We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC2N and C-doped BNNTs. Four different types of BC2N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. - Graphical Abstract: We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC2N and C-doped BNNTs. Four different types of BC2N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. Highlights: ? We investigated electronic properties of flattened BC2N nanotubes. ? The electronic states depend strongly on compression. ? It is studied flattened BN nanotubes doped with a carbon atom. ? The flattened C-doped structures, presents a significant reduction of the gap.

  13. Developing superplastic properties in an aluminum alloy through severe plastic deformation

    Lee, S.; Berbon, P.B. [University of Southern California, Los Angeles, CA (United States). Dept. of Materials Science; Furukawa, M. [Department of Technology, Fukuoka University of Education, Munakata, Fukuoka (Japan); Horita, Z.; Nemoto, M. [Department of Materials Science and Engineering, Kyushu University, Fukuoka (Japan); Tsenev, N.K. [Institute of Chemical Technology, Ufa State Petroleum Technical University, Ufa (Russian Federation); Valiev, R.Z. [Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa (Russian Federation); Langdon, T.G. [Departments of Materials Science and Mechanical Engineering University of Southern California, Los Angeles (United States)

    1999-11-15

    Equal-channel angular (ECA) pressing is a processing procedure which subjects a material to severe plastic deformation. Tests were conducted on a commercial cast aluminum alloy to evaluate the properties associated with samples subjected to three different ECA pressing procedures. The results show that all three procedures lead to an ultrafine microstructure and each procedure is capable of producing samples which exhibit high strain rate superplasticity. Optimum superplastic properties were achieved in samples subjected to ECA pressing to a strain of {proportional_to}12. Under these conditions, the measured elongations to failure at a temperature of 673 K were 1210 and 950% at strain rates of 10{sup -1} and 1 s{sup -1}, respectively. (orig.)

  14. Effect of deformation and annealing on the microstructure and magnetic properties of grain-oriented electrical steels

    The effect of plastic deformation and subsequent annealing on the magnetic properties and microstructure of a grain-oriented (GO) electrical steel has been studied. True strain (?) from 0.002 to 0.23 was applied by rolling in two directions, rolling (RD) and transverse (TD). The deterioration of power losses varies according to the direction of deformation. Annealing the strained material-at 800 deg. C/2 h-leads to a recrystallization and restored magnetic properties. The main components of annealed-textures are around 15-35o from those of deformed-textures for both RD and TD. Rolling along {1 1 0} direction leads to the development of deformation twins

  15. Ion-cyclotron-resonance heating in the Wisconsin Levitated Octupole

    Ion-cyclotron-resonance heating has been investigated, both experimentally and theoretically, on the Wisconsin Levitated Octupole. Heating of both ions and electrons has been observed. Typically, a two-component ion energy distribution is produced (300 eV and 50 eV) with 500 kW of rf power coupled into a 5 x 1012 cm-3 plasma. Power is coupled to the plasma with an antenna that also serves as the inductor of an oscillator tank circuit. The oscillator is tunable from 1 to 3 MHz and can be applied for periods up to 10 msec. The experiments were performed with hydrogen, gun-injected plasmas. Most of the theortical work presented deals with a calculation that predicts the plasma loading. A slab model is used, and the questions of accessibility, polarization, and damping of the radio-frequency electromagnetic fields are addressed. It is found that cold-plasma theory cannot account for the heating and, therefore, hot-plasma theory is invoked to explain the results. The loading measurements and theoretical predictions are found to be in reasonable agreement

  16. Octupole Focusing Relativistic Self-Magnetometer Electric Storage Ring "Bottle"

    Talman, Richard

    2015-01-01

    A method proposed for measuring the electric dipole moment (EDM) of a charged fundamental particle such as the proton, is to measure the spin precession caused by a radial electric bend field $E_r$, acting on the EDMs of frozen spin polarized protons circulating in an all-electric storage ring. The dominant systematic error limiting such a measurement comes from spurious spin precession caused by unintentional and unknown average radial magnetic field $B_r$ acting on the (vastly larger) magnetic dipole moments (MDM) of the protons. Along with taking extreme magnetic shielding measures, the best protection against this systematic error is to use the storage ring itself, as a "self-magnetometer"; the exact magnetic field average $\\langle B_r\\rangle$ that produces systematic EDM error, is nulled to exquisite precision by orbit position control. By using octupole rather than quadrupole focusing the restoring force can be vanishingly small for small amplitude vertical betatron-like motion yet strong enough at larg...

  17. Observation of the Nuclear Magnetic Octupole Moment of 137Ba+

    Hoffman, Matthew

    Single trapped ions are ideal systems in which to test atomic physics at high precision, which can in turn be used for searches for violations of fundamental symmetries and physics beyond the standard model, in addition to quantum computation and a number of other applications. The ion is confined in ultra-high vacuum, is laser cooled to mK temperatures, and kept well isolated from the environment which allows these experimental efforts. In this thesis, a few diagnostic techniques will be discussed, covering a method to measure the linewidth of a narrowband laser in the presence of magnetic field noise, as well as a procedure to measure the ion's temperature using such a narrowband laser. This work has led to two precision experiments to measure atomic structure in 138Ba+, and 137Ba+ discussed here. First, employing laser and radio frequency spectroscopy techniques in 138Ba+, we measured the Lande- gJ factor of the 5D5/2 level at the part-per-million level, the highest precision to date. Later, the development of apparatus to efficiently trap and laser cool 137Ba+ has enabled a measurement of the hyperfine splittings of the 5D3/2 manifold, culminating in the observation of the nuclear magnetic octupole moment of 137Ba+.

  18. Deformed bialgebra of diffeomorphisms

    We review some of the properties of deformed spaces. Especially, the concept of derivatives is analyzed in detail. As a new result we present the deformed bialgebra of diffeomorphisms and among them the special example of deformed Lorentz transformations. (author)

  19. Investigation of the rheological properties of planetary ice-rock analogues using triaxial deformation and neutron diffraction experiments.

    Middleton, C.

    2012-01-01

    In this thesis I present work on the rheological properties of ice-rock mixtures, with particular application to the flow of materials in icy planetary bodies. Details of manufacture of analogue samples, triaxial deformation experiments, and combined deformation and neutron diffraction experiments are presented. These experimental results are used to consider the effect of an ice rock rheology on planetary processes through computer modelling of the evolution of the dwarf planet Ceres. Water ...

  20. Bending Deformation and Fatigue Properties of Precision-Casted TiNi Shape-Memory Alloy Brain Spatula

    Tobushi, Hisaaki; KITAMURA, KAZUHIRO; Yoshimi, Yukiharu; Date, Kousuke

    2010-01-01

    In order to develop the SMA-brain spatula, the mechanical characteristics of the TiNi castand rolled-SMAs and the copper used for the brain spatula were compared based on the tensile deformation properties, and the characteristics of the SMA-brain spatula were discussed. The fatigue properties of these materials were also investigated by the pulsating-

  1. Optomechanical properties of cancer cells revealed by light-induced deformation and quantitative phase microscopy

    Kastl, Lena; Budde, Björn; Isbach, Michael; Rommel, Christina; Kemper, Björn; Schnekenburger, Jürgen

    2015-05-01

    There is a growing interest in cell biology and clinical diagnostics in label-free, optical techniques as the interaction with the sample is minimized and substances like dyes or fixatives do not affect the investigated cells. Such techniques include digital holographic microscopy (DHM) and the optical stretching by fiber optical two beam traps. DHM enables quantitative phase contrast imaging and thereby the determination of the cellular refractive index, dry mass and the volume, whereas optical cell stretching reveals the deformability of cells. Since optical stretching strongly depends on the optical properties and the shape of the investigated material we combined the usage of fiber optical stretching and DHM for the characterization of pancreatic tumor cells. The risk of tumors is their potential to metastasize, spread through the bloodstream and build distal tumors/metastases. The grade of dedifferentiation in which the cells lose their cell type specific properties is a measure for this metastatic potential. The less differentiated the cells are, the higher is their risk to metastasize. Our results demonstrate that pancreatic tumor cells, which are from the same tumor but vary in their grade of differentiation, show significant differences in their deformability. The retrieved data show that differentiated cells have a higher stiffness than less differentiated cells of the same tumor. Even cells that differ only in the expression of a single tumor suppressor gene which is responsible for cell-cell adhesions can be distinguished by their mechanical properties. Additionally, results from DHM measurements yield that the refractive index shows only few variations, indicating that it does not significantly influence optical cell stretching. The obtained results show a promising new approach for the phenotyping of different cell types, especially in tumor cell characterization and cancer diagnostics.

  2. Octupole correlations in positive-parity states of rare-earth and actinide nuclei

    Spieker M.

    2015-01-01

    Full Text Available In this contribution, further evidence of the importance of multiphonon-octupole excitations to describe experimental data in the rare earths and actinides will be presented. First, new results of a (p, t experiment at the Q3D magnetic spectrograph in Munich will be discussed, which was performed to selectively excite J? = 0+ states in 240Pu. spdf interacting boson model (IBM calculations suggest that the previously proposed double-octupole phonon nature of the J? = 0+2 state is not in conflict with its strong (p, t population. Second, the framework of the IBM has been adopted for the description of experimental observables related to octupole excitations in the rare earths. Here, the IBM is able to describe the signature splitting for positiveand negative-parity states when multi-dipole and multi-octupole bosons are included. The present study might support the idea of octupole-phonon condensation at intermediate spin (J? = 10+ leading to the change in yrast structure observed in 146Nd.

  3. Effects of dehydration on the viscoelastic properties of vocal folds in large deformations.

    Miri, Amir K; Barthelat, François; Mongeau, Luc

    2012-11-01

    Dehydration may alter vocal fold viscoelastic properties, thereby hampering phonation. The effects of water loss induced by an osmotic pressure potential on vocal fold tissue viscoelastic properties were investigated. Porcine vocal folds were dehydrated by immersion in a hypertonic solution, and quasi-static and low-frequency dynamic traction tests were performed for elongations of up to 50%. Digital image correlation was used to determine local strains from surface deformations. The elastic modulus and the loss factor were then determined for normal and dehydrated tissues. An eight-chain hyperelastic model was used to describe the observed nonlinear stress-stretch behavior. Contrary to the expectations, the mass history indicated that the tissue absorbed water during cyclic extension when submerged in a hypertonic solution. During loading history, the elastic modulus was increased for dehydrated tissues as a function of strain. The response of dehydrated tissues was much less affected when the load was released. This observation suggests that hydration should be considered in micromechanical models of the vocal folds. The internal hysteresis, which is often linked to phonation effort, increased significantly with water loss. The effects of dehydration on the viscoelastic properties of vocal fold tissue were quantified in a systematic way. A better understanding of the role of hydration on the mechanical properties of vocal fold tissue may help to establish objective dehydration and phonotrauma criteria. PMID:22483778

  4. Evaluation on plastic deformation property of copper nano-film by nano-scale cantilever specimen

    We investigate the elasto-plastic deformation properties of a 20-nm-thick copper (Cu) thin film. A nano-scale cantilever specimen is fabricated from multilayer thin films, where the Cu thin film is sandwiched between a silicon nitride layer and a silicon substrate. During bending, the load, P, and displacement, d, are carefully monitored using an electron microscope, and a distinct non-linearity is observed. The plastic constitutive equation of the Cu thin film, which is assumed to obey a power hardening law (σ = Rεn (σ > σy)), is inversely derived by finite element method fitting the experimental results. The residual stress in each layer is experimentally examined, and the effect is included in the inverse analysis. We obtain σ = 3316ε0.29 [MPa] and a yield stress of 765 MPa for the Cu film. The yield stress is about 10 times higher than that of the bulk, and the exponent is also larger. Moreover, inverse analysis based on the bending experiment data, without considering the residual stress, gives a good approximation of the plastic law. This is because the plastic deformation preferentially takes place at the top and bottom surfaces, where the residual stress is relieved during fabrication of the specimen.

  5. FlexyDos3D: a deformable anthropomorphic 3D radiation dosimeter: radiation properties.

    De Deene, Y; Skyt, P S; Hil, R; Booth, J T

    2015-02-21

    Three dimensional radiation dosimetry has received growing interest with the implementation of highly conformal radiotherapy treatments. The radiotherapy community faces new challenges with the commissioning of image guided and image gated radiotherapy treatments (IGRT) and deformable image registration software.A new three dimensional anthropomorphically shaped flexible dosimeter, further called 'FlexyDos3D', has been constructed and a new fast optical scanning method has been implemented that enables scanning of irregular shaped dosimeters. The FlexyDos3D phantom can be actuated and deformed during the actual treatment. FlexyDos3D offers the additional advantage that it is easy to fabricate, is non-toxic and can be molded in an arbitrary shape with high geometrical precision.The dosimeter formulation has been optimized in terms of dose sensitivity. The influence of the casting material and oxygen concentration has also been investigated. The radiophysical properties of this new dosimeter are discussed including stability, spatial integrity, temperature dependence of the dosimeter during radiation, readout and storage, dose rate dependence and tissue equivalence. PMID:25615261

  6. FlexyDos3D: a deformable anthropomorphic 3D radiation dosimeter: radiation properties

    Three dimensional radiation dosimetry has received growing interest with the implementation of highly conformal radiotherapy treatments. The radiotherapy community faces new challenges with the commissioning of image guided and image gated radiotherapy treatments (IGRT) and deformable image registration software. A new three dimensional anthropomorphically shaped flexible dosimeter, further called ‘FlexyDos3D’, has been constructed and a new fast optical scanning method has been implemented that enables scanning of irregular shaped dosimeters. The FlexyDos3D phantom can be actuated and deformed during the actual treatment. FlexyDos3D offers the additional advantage that it is easy to fabricate, is non-toxic and can be molded in an arbitrary shape with high geometrical precision. The dosimeter formulation has been optimized in terms of dose sensitivity. The influence of the casting material and oxygen concentration has also been investigated. The radiophysical properties of this new dosimeter are discussed including stability, spatial integrity, temperature dependence of the dosimeter during radiation, readout and storage, dose rate dependence and tissue equivalence. (paper)

  7. Evaluation on plastic deformation property of copper nano-film by nano-scale cantilever specimen

    Sumigawa, Takashi, E-mail: sumigawa@cyber.kues.kyoto-u.ac.j [Department of Mechanical Engineering and Science, Kyoto University, Kyoto 606-8501 (Japan); Shishido, Tetsuya; Murakami, Tadashi [Department of Mechanical Engineering and Science, Kyoto University, Kyoto 606-8501 (Japan); Iwasaki, Tomio [Mechanical Engineering Research Laboratory, Hitachi, Ltd., Katsuta, Ibaraki 312-0034 (Japan); Kitamura, Takayuki [Department of Mechanical Engineering and Science, Kyoto University, Kyoto 606-8501 (Japan)

    2010-08-31

    We investigate the elasto-plastic deformation properties of a 20-nm-thick copper (Cu) thin film. A nano-scale cantilever specimen is fabricated from multilayer thin films, where the Cu thin film is sandwiched between a silicon nitride layer and a silicon substrate. During bending, the load, P, and displacement, d, are carefully monitored using an electron microscope, and a distinct non-linearity is observed. The plastic constitutive equation of the Cu thin film, which is assumed to obey a power hardening law ({sigma} = R{epsilon}{sup n} ({sigma} > {sigma}{sub y})), is inversely derived by finite element method fitting the experimental results. The residual stress in each layer is experimentally examined, and the effect is included in the inverse analysis. We obtain {sigma} = 3316{epsilon}{sup 0.29} [MPa] and a yield stress of 765 MPa for the Cu film. The yield stress is about 10 times higher than that of the bulk, and the exponent is also larger. Moreover, inverse analysis based on the bending experiment data, without considering the residual stress, gives a good approximation of the plastic law. This is because the plastic deformation preferentially takes place at the top and bottom surfaces, where the residual stress is relieved during fabrication of the specimen.

  8. Plasma Confinement in a Toroidal Octupole Magnetic Field

    The confinement of low-density (n = 109 cm-3) collisionless plasmas with Ti ? 40 eV, Te ? 10 eV produced by gun injection or with Te ? 1 eV. Ti -3of the Bohm diffusion coefficient which was not large enough to produce the observed radial loss. Studies were also made to determine the importance of low-frequency fluctuations or convective cells which may have been produced by injection, magnetic field perturbations or azimuthal density variations. The addition of a toroidal magnetic field decreased the lifetime slightly and generated large-scale convective cells in the shearless layer near the plasma surface. Currents parallel to the magnetic field have been observed which must be considered in determining the cause of increased fluctuation with the increase of the toroidal field. The mechanical supports were also guarded with magnetic dipoles in the manner proposed by Lehnert. The plasma flux to one of the supports was reduced for the hot ion plasma by an order of magnitude when there was one ion gyroradius between the mechanical support and the guard field separatrix. However, the plasma flux along the guard field separatrix increased to the value of the original support flux and there was a negligible ( ? 20%) improvement of the lifetime. An inductively excited, magnetically force-free octupole is being assembled with transiently withdrawn supports to eliminate the plasma loss to hoop supports. The device will provide at least 10 msec of experimental time during which only 5% of the magnetic flux diffuses into the internal hoops. 100 eV protons will have 15 gyroradii on each side of the separatrix. (author)

  9. Formation of structure and properties of commercial titanium with nanocrystalline structure after deformation and subsequent heating

    The influence of shear deformation degree on grain size and mechanical properties of titanium VT1-0 alloy was investigated. it is revealed that the structure with mean grain size of 100 nm can be produced by way of intense torsion. As this takes place some areas with grain size of 20-30 nm can exist. Postdeformation heating results in two main stages of structural transformations. The low temperature transformation (below 250 deg C) proceeds with a fairly high rate and involves stress and dislocation redistribution. Transformations above 300 deg C proceed by recrystallization mechanism. Nanocrystalline commercial titanium exhibits the best combination of strength and plasticity being annealed at 250 deg C

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

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

    2008-10-15

    A surface severe plastic deformation (S{sup 2}PD) method has been applied to bulk specimens of HASTELLOY C-2000 alloy, a nickel-base alloy. The mechanical properties of the processed C-2000 alloy were determined via tensile tests and Vickers hardness measurements, whereas the microstructure was characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The improved tensile strength was related to the nanostructure at the surface region, the residual compressive stresses, and the work-hardened surface layer, all of which resulted from the S{sup 2}PD process. To understand the contributions of these three factors, finite element modeling was performed. It was found that the improved tensile strength could be interpreted based on the contributions of nano-grains, residual stresses, and work hardening.

  11. The Properties of Bulk Ultrafine-Grained Metals Processed Through the Application of Severe Plastic Deformation

    Langdon, Terence G.

    Processing through the application of severe plastic deformation (SPD) provides a very attractive tool for the production of bulk ultrafine-grained materials. These materials typically have grain sizes in the submicrometer or nanometer ranges and they exhibit high strength at ambient temperature and, if the ultrafine grains are reasonably stable at elevated temperatures, they have a potential for use in superplastic forming operations. Several procedures are now available for applying SPD to metal samples but the most promising are Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT). This paper examines the basic principles of ECAP and HPT and describes some of the properties that may be achieved using these processing techniques.

  12. Structure evolution and changes in magnetic properties of severe plastic deformed Nd(Pr)-Fe-B alloys during annealing

    Structural changes and hysteresis properties of Nd(Pr)-Fe-B alloys of various compositions were studied after severe torsion straining under high pressure and following annealing. It was shown that in all the alloys studied, severe plastic deformation leads to formation of ultrafine-grained non-equilibrium structure and, at extremely large strains, even to formation of an amorphous structure. Annealing resulted in crystallization of alloys, formation of stable magnetic and non-magnetic phases and in marked improvements in hard magnetic properties. Homogenization of alloys is responsible for an increase in coercivity of the deformed samples. (orig.)

  13. Lattice Distortion and Octupole Ordering Model in CexLa1-xB6

    Kubo, K; Kubo, Katsunori; Kuramoto, Yoshio

    2003-01-01

    Possible order parameters of the phase IV in CexLa1-xB6 are discussed with special attention to the lattice distortion recently observed. A \\Gamma_{5u}-type octupole order with finite wave number is proposed as the origin of the distortion along the [111] direction. The \\Gamma_8 crystalline electric field (CEF) level splits into three levels by a mean field with the \\Gamma_{5u} symmetry. The ground and highest singlets have the same quadrupole moment, while the intermediate doublet has an opposite sign. It is shown that any collinear order of \\Gamma_{5u}-type octupole moment accompanies the \\Gamma_{5g}-type ferro-quadrupole order, and the coupling of the quadrupole moment with the lattice induces the distortion. The cusp in the magnetization at the phase transition is reproduced, but the internal magnetic field due to the octupole moment is smaller than the observed one by an order of magnitude.

  14. Accretion onto Stars with Octupole Magnetic Fields: Matter Flow, Hot Spots and Phase Shifts

    Long, Min; Lamb, Frederick K

    2009-01-01

    Recent measurements of the surface magnetic fields of classical T Tauri stars (CTTSs) and magnetic cataclysmic variables show that their magnetic fields have a complex structure. The magnetic field associated with the octupole moment may dominate the magnetic field associated with other moments in some stars, such as the CTTS V2129 Oph. Previously, we studied disc accretion onto stars with magnetic fields described by a superposition of aligned or misaligned dipole and quadrupole moments. In this paper, we present results of the first simulations of disc accretion onto stars with an \\textit {octupole} field. As examples, we consider stars with a superposition of octupole and dipole fields of different strengths and investigate matter flow around them, the shapes of hot spots on their surfaces, and the light curves produced by their rotation. We investigate two possible mechanisms for producing phase shifts in the light curves of stars with complex fields: (1) change of the star's intrinsic magnetic field and ...

  15. Optimization of the magnetic properties of FePd alloys by severe plastic deformation

    Chbihi, Abdelahad; Sauvage, Xavier; Genevois, Ccile; Blavette, Didier; Gunderov, Dmitry; Popov, Alexander

    2012-01-01

    A FePd alloy was nanostructured by severe plastic deformation following two different routes: ordered and disordered states were processed by high pressure torsion (HPT). A grain size in a range of 50 to 150 nm is obtained in both cases. Severe plastic deformation induces some significant disordering of the long range ordered L10 phase. However, Transmission Electron Microscopy (TEM) data clearly show that few ordered nanocrystals remain in the deformed state. The deformed materials were anne...

  16. Rare-earth nuclei: Radii, isotope-shifts and deformation properties in the relativistic mean field theory

    A systematic study of the ground-state properties of even-even rare earth nuclei has been performed in the framework of the Relativistic Mean-Field (RMF) theory using the parameter set NL-Sh. Nuclear radii, isotope shifts and deformation properties of the heavier rare-earth nuclei have been obtained, which encompass atomic numbers ranging from Z=60 to Z=70 and include a large range of isospin. It is shown that RMF theory is able to provide a good and comprehensive description of the empirical binding energies of the isotopic chains. At the same time the quadrupole deformations β2 obtained in the RMF theory are found to be in good agreement with the available empirical values. The theory predicts a shape transition from prolate to oblate for nuclei at neutron number N=78 in all the chains. A further addition of neutrons up to the magic number 82 brings about the spherical shape. For nuclei above N-82, the RMF theory predicts the well-known onset of prolate deformation at about N-88, which saturates at about N-102. The deformation properties display an identical behaviour for all the nuclear chains. A good description of the above deformation transitions in the RMF theory in all the isotopic chains leads to a successful reproduction of the anomalous behaviour of the empirical isotopic shifts of the rare-earth nuclei. The RMF theory exhibits a remarkable success in providing a unified and microscopic description of various empirical data. (orig.)

  17. Specifications of the octupole magnets required for the ATF2 ultra-low * lattice

    Marin, E.; /SLAC; Modena, M.; /CERN; Tauchi, T.; Terunuma, N.; /KEK, Tsukuba; Tomas, R.; /CERN; White, G.R.; /SLAC

    2014-05-28

    The Accelerator Test Facility 2 (ATF2) aims to test the novel chromaticity correction for higher chromaticity lattices as the one of CLIC. To this end the ATF2 ultra-low * lattice is designed to vertically focus the beam at the focal point or usually referred to as interaction point (IP), down to 23 nm. However when the measured multipole components of the ATF2 magnets are considered in the simulations, the evaluated spot sizes at the IP are well above the design value. The designed spot size is effectively recovered by inserting a pair of octupole magnets. In this note we address the technical specifications required for these octupole magnets.

  18. Specifications of the octupole magnets required for the ATF2 ultra-low β* lattice

    The Accelerator Test Facility 2 (ATF2) aims to test the novel chromaticity correction for higher chromaticity lattices as the one of CLIC. To this end the ATF2 ultra-low β* lattice is designed to vertically focus the beam at the focal point or usually referred to as interaction point (IP), down to 23 nm. However when the measured multipole components of the ATF2 magnets are considered in the simulations, the evaluated spot sizes at the IP are well above the design value. The designed spot size is effectively recovered by inserting a pair of octupole magnets. In this note we address the technical specifications required for these octupole magnets

  19. Postseismic Deformations of the Aceh, Nias and Benkulu Earthquakes and the Viscoelastic Properties of the Mantle

    Fleitout, L.; Garaud, J.; Cailletaud, G.; Vigny, C.; Simons, W. J.; Ambrosius, B. A.; Trisirisatayawong, I.; Satirapod, C.; Geotecdi Song

    2011-12-01

    The giant seism of Aceh (december 2004),followed by the Nias and Bengkulu earthquakes, broke a large portion of the boundary between the Indian ocean and the Sunda block. For the first time in history, the deformations associated with a very large earthquake can be followed by GPS, in particular by the SEAMERGE (far-field) and SUGAR (near-field) GPS networks. A 3D finite element code (Zebulon-Zset) is used to model both the cosismic and the postseismic deformations. The modeled zone is a large portion of spherical shell around Sumatra extanding over more than 60 degrees in latitude and longitude and from the Earth's surface to the core-mantle boundary. The mesh is refined close to the subduction zone. First, the inverted cosismic displacements on the subduction plane are inverted for and provide a very good fit to the GPS data for the three seisms. The observed postseismic displacements, non-dimensionalized by the cosismic displacements, present three very different patterns as function of time: For GPS stations in the far-field, the total horizontal post-seismic displacement after 4 years is as large as the cosismic displacement. The velocities vary slowly over 4 years. A large subsidence affects Thailand and Malaysia. In the near-field, the postseismic displacement reaches only some 15% of the cosismic displacement and it levels off after 2 years. In the middle-field (south-west coast of Sumatra), the postseismic displacement also levels-off with time but more slowly and it reaches more than 30% of the cosismic displacement after four years. In order to fit these three distinct displacement patterns, we need to invoke both viscoelastic deformation in the asthenosphere and a low-viscosity wedge: Neither the vertical subsidence nor the amplitude of the far-field horizontal velocities could be explained by postseismic sliding on the subduction interface. The low viscosity wedge permits to explain the large middle-field velocities. The viscoelastic properties of the asthenosphere are consistent with a Burger rheology with a transient creep represented by a Kelvin-Voigt element with a viscosity of 3.1018Pas and μ Kelvin}=μ {elastic/3. A second Kelvin-Voigt element with very limited amplitude may explain some characteristics of the short time-scale signal. The viscosity of the low viscosity wedge is also of the order of 3. 1018 Pas. The near-field displacements are not explained by viscoelastic relaxation and post-seismic slip on the fault plane (15% of the cosismic slip) occured in the months after the earthquakes. These large post-seismic deformations affect the deviatoric stresses in the whole Sunda-block. They also imply sizable far-field interseismic deformations.

  20. The influence of hydrogen, deformation geometry, and grain size on the rheological properties of olivine at upper mantle conditions

    Tielke, Jacob A.

    Many important geophysical processes, including mantle convection and the associated movement of Earth's tectonic plates, are strongly dependent upon the rheological properties of Earth's upper mantle. Olivine is the most abundant mineral in the upper mantle and therefore largely controls the mechanical behavior of this region of Earth's interior. Many experimental investigations have been carried out to study the rheological properties of olivine single crystals, synthetically produced aggregates, and naturally occurring mantle rocks at asthenospheric temperatures. In contrast, relatively few studies have focused on measuring the rheological properties of olivine deforming at lithospheric temperatures. Furthermore, there are several unanswered questions about the microphysical processes that control deformation of olivine at upper mantle conditions. One outstanding question in the field of rock and mineral physics is Do different microphysical processes control the rate of deformation of olivine at asthenospheric compared to lithospheric mantle conditions? To address this question we carried out direct shear experiments on olivine single crystals at temperatures that span the transition from lithospheric to asthenospheric mantle conditions. The results of these experiments, which are presented in Chapter 2, demonstrate that the dependence of strain rate upon stress transitions from a power-law relationship at high temperatures to an exponential dependence at lower temperatures. This transition in rheological behavior is consistent with deformation that is controlled by the climb of dislocations at high-temperature conditions and deformation that is controlled by the glide of dislocations at low-temperature conditions. Furthermore, the direct shear geometry allows for isolation of the (001)[100] and (100)[001] dislocation slip systems, which cannot be individually activated in triaxial compression. At high-temperature conditions, crystals oriented for shear on the (001)[100] slip system are observed to be weaker than crystals oriented for shear on the (100)[001] slip system. At low-temperature conditions the opposite relationship is observed: crystals oriented for shear on the (100)[001] slip system are weakest. Another important outstanding question is Do the mechanisms of hydrolytic weakening in olivine differ at asthenospheric compared to lithospheric mantle conditions? In Chapter 3 we report the results of experiments carried out on olivine single crystals under hydrous conditions at both asthenospheric and lithospheric temperatures. For crystals deformed at high-temperatures and under hydrous conditions, the dependence of strain rate on stress follows a power-law relationship with a stress exponent (n) of ~2.5, consistent with deformation that is rate limited by diffusion of silicon through the olivine lattice. In contrast, crystals deformed at high-temperatures and under anhydrous conditions yield n values of ~3.5, consistent with deformation that is rate limited by diffusion of silicon through the cores of dislocations. At low temperature conditions, the strain rate of both hydrous and anhydrous crystals are equally well described by the same exponential dependence of stress. These observations demonstrate significant hydrolytic weakening occurs at asthenospheric temperatures, but hydrolytic weakening cannot be resolved at lithospheric temperatures for our experimental conditions. Lastly, we address a question about polycrystalline deformation: What deformation mechanism is responsible for grain-size sensitive (GSS) power-law creep of olivine aggregates? In Chapter 4 we compare strain rates measured during deformation experiments on olivine aggregates to strain rates calculated from a micromechanical model of intragranular slip. The micromechanical model uses the measured stress from deformation experiments and grain orientations determined from post-deformation electron backscatter diffraction measurements to approximate the contribution of dislocation creep to the strain rate. Olivine aggregates deform up to a f

  1. Mechanical properties and constitutive relations for tantalum and tantalum alloys under high-rate deformation

    Tantalum and its alloys have received increased interest as a model bcc metal and for defense-related applications. The stress-strain behavior of several tantalums, possessing varied compositions and manufacturing histories, and tantalum alloyed with tungsten, was investigated as a function of temperature from -196 C to 1,000 C, and strain rate from 10-3 s-1 to 8,000 s-1. The yield stress for all the Ta-materials was found to be sensitive to the test temperature, the impurity and solute contents; however, the strain hardening remained very similar for various ''pure'' tantalums but increased with alloying. Powder-metallurgy (P/M) tantalum with various levels of oxygen content produced via different processing paths was also investigated. Similar mechanical properties compared to conventionally processed tantalums were achieved in the P/M Ta. This data suggests that the frequently observed inhomogeneities in the mechanical behavior of tantalum inherited from conventional processes can be overcome. Constitutive relations based upon the Johnson-Cook, the Zerilli-Armstrong, and the Mechanical Threshold Stress models were evaluated for all the Ta-based materials. Parameters were also fit for these models to a tantalum-bar material. Flow stresses of a Ta bar stock subjected to a large-strain deformation of var-epsilon = 1.85 via multiple upset forging were obtained. The capabilities and limitations of each model for large-strain applications are examined. The deformation mechanisms controlling high-rate plasticity in tantalum are revisited

  2. Influence of sensitizing additives on deformation-strength properties of radiation vulcanized rubber

    Full text: Expanding the practical use of products of radiation-vulcanized elastopolymers (RVEP) makes it necessary to increase their operational properties. Applied to the exploitation of polymers in the field of the ionizing radiation does not always meet shown requirements to them. In the present report the influence of sensitizer of disulpho chloride aromatic compounds on deformation-strength and their ageing under the influence of radiation exposure is being examined. The serial produced aromatic compounds of disulpho chloride bezene (DSCB) were used as sensitizers. It is established that, during the sensitization of radiation chemical vulcanization the mixture of butadiene-nitrile rubber with PVC with other ingredients affect the density of the spatial grid which determines the mechanical properties of vulcanized rubber. Two processes simultaneously run in the presence of sensitizing additives: inhibition of radiation oxidation which causes cross-linking and formation of the spatial grid in BNC. The role of sensitizer in the process of radiation vulcanization is defined first of all by reducing the doze of irradiation in the vulcanization process; simultaneously accelerate the cross-linking of the polymer chains. On the base of physical mechanical and structure of DSCB, can be judged that the influence of ionizing radiation leads the polar groups to ionization besides, their excited potential during ionization is very high which provides material with radiation resistance. Considering the resistance of DSCB to radiation, its practical value is high and can conduct vulcanization at low doses (150-300 kGy). (authors)

  3. Investigation of structure and properties of Co-Cr-Mo alloy in as-cast and hot-deformed states

    The microstructure, phase composition and mechanical properties of as-cast and hot-deformed samples of Co-Cr-Mo alloys were investigated using the methods of metallographic and X-ray diffraction analyses during furnace and rapid heating. (authors).

  4. The influence of severe plastic deformation on the structure and magnetic properties of a Pr-Fe-B-Cu alloy

    The influence of severe plastic torsion straining under pressure on the structure and magnetic properties of the alloy Pr20 Fe 73.5 N 5 Cu 1.5 at % is considered in the present work. Deformation results in the formation of an ultrafine-gained structure and subsequent annealing leads to an increase in coercivity to 1500 kA/m. (authors)

  5. Experimental study of dynamic compressive properties of rigid polyurethane foams under high deformation velocities using an impulsive shock technique

    This paper presents an experimental study on dynamic compressive properties of rigid urethane foams under high deformation velocities realized by means of an impulsive shock device. Two kind of rigid foams are studied within the impulse range: 500 pa. s to 1.200 pa.s. Experimental results are analysed and a comparison between static and dynamic behaviour is made

  6. Interpretation of fluid inclusions in quartz deformed by weak ductile shearing: reconstruction of differential stress magnitudes and pre-deformation fluid properties

    Tarantola, Alexandre; Diamond, Larryn W.

    2015-04-01

    A well developed theoretical framework is available in which paleofluid properties, such as chemical composition and density, can be reconstructed from fluid inclusions in minerals that have undergone no ductile deformation. Fluid inclusions are known to reequilibrate during strong post-entrapment changes in hydrostatic confining pressure (e.g. Sterner and Bodnar 1989). The present study extends this framework to encompass fluid inclusions hosted by quartz that has undergone weak ductile deformation following fluid entrapment. Recent piston-cylinder experiments (Griggs apparatus) made on single quartz crystals have shown that such deformation causes inclusions to become dismembered into clusters of irregularly shaped relict inclusions surrounded by planar arrays of tiny, new-formed (neonate) inclusions (Diamond et al. 2010; Tarantola et al. 2010, 2012). Comparison of the experimental samples with a naturally sheared quartz vein from Grimsel Pass, Central Alps, Switzerland, reveals striking similarities. This strong concordance justifies applying the experimentally derived rules of fluid inclusion behaviour to nature. Thus, planar arrays of dismembered inclusions defining cleavage planes in quartz may be taken as diagnostic of small amounts of intracrystalline strain. Deformed inclusions preserve their pre-deformation concentration ratios of gases to electrolytes, but their H2O contents typically have changed. Morphologically intact inclusions, in contrast, preserve the pre-deformation composition and density of their originally trapped fluid. The orientation of the maximum principal compressive stress (?1) at the time of shear deformation can be derived from the pole to the cleavage plane within which the dismembered inclusions are aligned. Finally, the density of neonate inclusions is commensurate with the pressure value of ?1 at the temperature and time of deformation. This last rule offers a means to estimate magnitudes of shear stresses from fluid inclusion studies. Application of this new paleopiezometer approach to the Grimsel vein yields a differential stress (?1 - ?3) of ~300 MPa at 390 30 C during late Miocene NNW-SSE orogenic shortening and regional uplift of the Aar Massif. This differential stress resulted in strain-hardening of the quartz at very low total strain (<5%) while nearby shear zones were accommodating significant displacements. Further implementation of these experimentally derived rules should provide new insight into processes of fluid-rock interaction in the ductile regime within the Earth's crust. Diamond, L.W., Tarantola, A., Stnitz, H., 2010. Modification of fluid inclusions in quartz by deviatoric stress II: Experimentally induced changes in inclusion volume and composition. Contrib. Mineral. Petrol. 160, 845-864. Sterner, S.M. and Bodnar, R.J., 1989. Synthetic fluid inclusions-VII. Re-equilibration of fluid inclusions in quartz during laboratory-simulated metamorphic burial and uplift. J. Metamorph. Geol., 7, 243-260. Tarantola, A., Diamond, L.W., Stnitz, H., 2010. Modification of fluid inclusions in quartz by deviatoric stress. I: Experimentally induced changes in inclusion shapes and microstructures. Contrib. Mineral. Petrol. 160, 825-843. Tarantola, A., Diamond, L.W., Stnitz, H., Thust, A., Pec, M., 2012. Modification of fluid inclusions in quartz by deviatoric stress. III: Influence of principal stresses on inclusion density and orientation. Contrib. Mineral. Petrol. 164, 527-550.

  7. Microstructure and properties of 700 MPa grade HSLA steel during high temperature deformation

    Highlights: • Hot deformation behavior of 700 MPa HSLA steel above 1200 °C in was detailed studied. • Uniform and granular bainite is formed when the deformation amount is 40%. • Deformation resistance value under steady-equilibrium state is about 56 MPa. - Abstract: A high temperature deformation experiment was conducted on a high strength low alloy (HSLA) steel Q690 using Thermecmastor-Z thermal/physical simulator. During the experiment, the specimens were heated from room temperature to 1200 °C with the heating rate of 10 °C/s and 50 °C/s, respectively. The deformation temperature was 1200 °C and the deformation amounts were 0%, 10% and 40%, respectively. The microstructures, stress–strain diagram and hardness were obtained. The results revealed that the microstructure transformation of deformed austenite was quite different from that of the normal situation. With the increasing of deformation amount, more lath-shaped microstructure and less granulous microstructure were observed. The compressive deformation effectively prevented the precipitation of carbides. Larger deformation amount or lower heating rate was conducive to the atomic diffusion, which led to the microstructure uniformity and hardness decreasing. The maximum stress was 68.4 MPa and the steady stress was about 56 MPa

  8. THE EFFECTS OF HYDROGEN, TRITIUM, AND HEAT TREATMENT ON THE DEFORMATION AND FRACTURE TOUGHNESS PROPERTIES OF STAINLESS STEEL

    Morgan, M.; Tosten, M.; Chapman, G.

    2013-09-06

    The deformation and fracture toughness properties of forged stainless steels pre-charged with tritium were compared to the deformation and fracture toughness properties of the same steels heat treated at 773 K or 873 K and precharged with hydrogen. Forged stainless steels pre-charged with tritium exhibit an aging effect: Fracture toughness values decrease with aging time after precharging because of the increase in concentration of helium from tritium decay. This study shows that forged stainless steels given a prior heat treatment and then pre-charged with hydrogen also exhibit an aging effect: Fracture toughness values decrease with increasing time at temperature. A microstructural analysis showed that the fracture toughness reduction in the heat-treated steels was due to patches of recrystallized grains that form within the forged matrix during the heat treatment. The combination of hydrogen and the patches of recrystallized grains resulted in more deformation twinning. Heavy deformation twinning on multiple slip planes was typical for the hydrogen-charged samples; whereas, in the non-charged samples, less twinning was observed and was generally limited to one slip plane. Similar effects occur in tritium pre-charged steels, but the deformation twinning is brought on by the hardening associated with decay helium bubbles in the microstructure.

  9. The study of magnetic properties, coercivity mechanism and bending strength of hot-deformed RE-Fe-B magnets

    The effect on mechanical properties and magnetic properties of hot-deformed magnets with different rare earth (RE) content has been investigated. The results show that the optimal comprehensive magnetic properties are obtained at 13.09 at% RE. The bending strength parallel to c-axis orientation increases with the increasing of RE content, while that perpendicular to c-axis orientation exhibits decrease. Moreover, the micro magnetic structure was observed and the coercivity mechanism of the hot-deformed magnet sample was discussed. - Highlights: • The optimal comprehensive magnetic properties are obtained at 13.09 at% RE. • The bending strength with different rare earth content is determined. • Domain wall moved irreversibly when the external field gets close to the coercivity. • Inhomogeneous domain wall pinning should be the dominant coercivity mechanism

  10. Deformed configurations, band structures and spectroscopic properties of = 50 Ge and Se nuclei

    S K Ghorui; C R Praharaj

    2014-04-01

    The deformed configurations and rotational band structures in =50 Ge and Se nuclei are studied by deformed Hartree–Fock with quadrupole constraint and angular momentum projection. Apart from the `almost’ spherical HF solution, a well-deformed configuration occurs at low excitation. A deformed well-mixed = 1/2+ neutron orbit comes down in energy (from the shell above = 50) to break the = 50 spherical shell closure. A = 7− isomer is predicted in 84Se at fairly low excitation energy. At higher excitation energies (8 MeV), a deformed band with = 7/2+–1/2− (based on $h_{11/2}$) neutron 1p–1h excitation, for 82Ge and 84Se, is shown in our calculation. Our study gives insight into possible deformed structures at spherical shell closure.

  11. Effect of cold deformation on structure and properties of aluminium alloy 1441 sheets

    The influence of tensile deformation on the 1441 alloy (Al-Cu-Mg-Li-Zr) in four states: quenched; quenched, straightened and naturally aged; annealed; quenched, straightened and artificially aged one, has been studied. It has been ascertained that deformation after quenching results in a considerable growth of yield strength. Artificial aging makes an insignificant contribution to stregthening of deformed sheet. 2 refs.; 4 figs

  12. Study of deformed nuclei properties using the Hartree-Fock method with the effective Skyrme-type interaction

    By the Hartree-Fock method with the effective Skyrme forces the program system is described to calculate a wide range of static and dynamic properties of deformed nuclei. Some improvements are realized in the developed algorithms of Hartree-Fock equations allowing to save the time and to improve simultaneously the computation accuracy. On the base of these programs the theoretical analysis of binding energies of light deformed nuclei is carried out and good agreement with experiment is obtained. The spectra of 25Mg single-particle levels a are calculated and an essential rearrangement of a self-consistent field at high spin values is found

  13. Possible discontinuity in octupole behaviour in the Pt-Hg region

    Values of B(E3;O1+ ? 31-) have been determined for the nuclei 194,196,198Pt by Coulomb excitation, giving 0.125(8), 0.102(4), and 0.084(18) e2b3, respectively. The results are discussed within the context of a previously suggested discontinuity in octupole behaviour in the Pt-Hg region

  14. Octupole Resonance in the AGS at High Intensity: A SIMBAD study

    We studied the Octupole (Montague) resonance in the AGS, in its high intensity mode, by tracking with the PIC code SIMBAD. We calculated, turn-by-turn, the betatron tune footprint from the eigenvalues of the one-turn matrix. We show that one should exercise particular caution when the betatron tunes are close together, since the matrix gives ambiguous results at the resonance

  15. Convective cells and their relationship to vortex diffusion in the Wisconsin Levitated Octupole

    The purpose of this thesis is two-fold: first, to present floating potential structure for different plasmas and operating parameters in the Wisconsin Levitated Octupole. Second, to show how the observed potential structure can be used, within the framework of vortex diffusion, to account for enhanced diffusion in the appropriate parameter regimes

  16. Single-beam measurements of LHC instability threshold in terms of octupole current

    Mounet, N; Buffat, X; Burov, A; Hemelsoet, G; Metral, E; Papotti, G; Pieloni, T; Pojer, M; Salvant, B; Trad, G

    2012-01-01

    This note summarizes two machine development (MD) studies aimed at determining the octupole current needed in the LHC in order to stabilize all headtail instabilities at 4TeV/c, before and after the squeeze, with tight collimator settings, and when a single beam (beam 2) at maximum intensity (1380 bunches, 2.1 1014 protons) is present in the machine. The MDs followed the normal physics operation procedure, at the notable exception that a single beam was used, the other beam containing only one non-colliding nominal bunch. Octupole current (with negative polarity in the focusing octupoles and the opposite in the defocusing ones) was decreased by small steps until the instability threshold was reached. This was performed in two distinct MDs, one before the squeeze and the other after it, testing also several chromaticity values and the effect of the transverse damper in the latter case. Octupole thresholds are shown in each case studied, as well as the rise times of the instabilities observed.

  17. Examination of different strengths of octupole correlations in neutron-rich Pr and Pm isotopes

    Thiamova, G.; Alexa, P.; Hons, Zdeněk; Simpson, G.S.

    2012-01-01

    Roč. 86, č. 4 (2012), 044334/1-044334/5. ISSN 0556-2813 R&D Projects: GA ČR GAP203/10/0310 Institutional support: RVO:61389005 Keywords : neutron rich nuclei * octupole correlations Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.715, year: 2012

  18. Investigation of microstructure and mechanical properties of hot worked NiAl bronze alloy with different deformation degree

    Lv, Yuting; Wang, Liqiang, E-mail: wang_liqiang@sjtu.edu.cn; Han, Yuanfei; Xu, Xiaoyan; Lu, Weijie, E-mail: luweijie@sjtu.edu.cn

    2015-09-03

    In this study, the forged NiAl bronze (NAB) were hot rolled with the deformation degree of 40%, 60%, 80%, 90% and 95% at 850 °C, respectively. Effects of rolling deformation degree on the microstructure and mechanical properties of the NAB alloy were investigated. Scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) methods were used to characterize the microstructure. The results show that α grains are refined by the dynamic recovery and recrystallization, penetration of β phase into α phase and particle-stimulated nucleation (PSN) of recrystallization during rolling. The refined grains make a main contribution to the increase of mechanical properties of rolled NAB. When the deformation degree is increased to 80%, the optimum tensile properties with ultimate strength of 861.3±8.5 MPa, yield strength of 634.5±7 MPa and elongation of 19.3±0.05% is obtained. With further increasing the deformation degree, the strength of rolled NAB alloy increase and the elongation decrease due to the increase of work hardening effect and the formation of martensitic nano-twins.

  19. Investigation of microstructure and mechanical properties of hot worked NiAl bronze alloy with different deformation degree

    In this study, the forged NiAl bronze (NAB) were hot rolled with the deformation degree of 40%, 60%, 80%, 90% and 95% at 850 °C, respectively. Effects of rolling deformation degree on the microstructure and mechanical properties of the NAB alloy were investigated. Scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) methods were used to characterize the microstructure. The results show that α grains are refined by the dynamic recovery and recrystallization, penetration of β phase into α phase and particle-stimulated nucleation (PSN) of recrystallization during rolling. The refined grains make a main contribution to the increase of mechanical properties of rolled NAB. When the deformation degree is increased to 80%, the optimum tensile properties with ultimate strength of 861.3±8.5 MPa, yield strength of 634.5±7 MPa and elongation of 19.3±0.05% is obtained. With further increasing the deformation degree, the strength of rolled NAB alloy increase and the elongation decrease due to the increase of work hardening effect and the formation of martensitic nano-twins

  20. Effect of severe plastic deformation on the specific heat and magnetic properties of cold rolled Gd sheets

    Taskaev, S.; Skokov, K.; Khovaylo, V.; Buchelnikov, V.; Pellenen, A.; Karpenkov, D.; Ulyanov, M.; Bataev, D.; Usenko, A.; Lyange, M.; Gutfleisch, O.

    2015-03-01

    We report on specific heat and magnetic properties of thin Gd sheets obtained by means of a cold rolling technique. At temperatures well below Curie temperature TC, the cold rolling has a minor impact on the specific heat Cp. However, a well defined λ-type anomaly of Cp seen in the vicinity of TC in a polycrystalline Gd sample is markedly suppressed in the severely deformed samples. Depression of the λ peak is due to a large decrease of magnetization that presumably originates in a local magnetic anisotropy induced by the severe plastic deformation. Results of calculation of magnetocaloric effect from the Cp and magnetization data indicate that the magnetocaloric effect gradually decreases as the degree of plastic deformation increases. This trend is further confirmed by the direct measurements of the adiabatic temperature change ΔTad.

  1. Deformed photon-added entangled squeezed vacuum and one-photon states: Entanglement, polarization, and nonclassical properties

    A, Karimi; M, K. Tavassoly

    2016-04-01

    In this paper, after a brief review on the entangled squeezed states, we produce a new class of the continuous-variable-type entangled states, namely, deformed photon-added entangled squeezed states. These states are obtained via the iterated action of the f-deformed creation operator A = f (n)a † on the entangled squeezed states. In the continuation, by studying the criteria such as the degree of entanglement, quantum polarization as well as sub-Poissonian photon statistics, the two-mode correlation function, one-mode and two-mode squeezing, we investigate the nonclassical behaviors of the introduced states in detail by choosing a particular f-deformation function. It is revealed that the above-mentioned physical properties can be affected and so may be tuned by justifying the excitation number, after choosing a nonlinearity function. Finally, to generate the introduced states, we propose a theoretical scheme using the nonlinear Jaynes–Cummings model.

  2. Microstructural Analysis of Severe Plastic Deformed Twin Roll Cast AZ31 for the Optimization of Superplastic Properties

    Young, John P.; Askari, Hesam A.; Heiden, Michael J.; Hovanski, Yuri; Field, David P.; Zbib, Hussein M.

    2013-07-08

    In recent years magnesium alloys have attracted significant attention as potential candidates to replace many of the heavier metals used in some automotive applications. However, the limited formability of magnesium and its alloys at room temperature has driven interest in the superplastic forming magnesium as an alternative shaping method. Severe plastic deformation techniques have become a well studied method of refining the grain size and modifying the microstructural characteristics of many magnesium alloys to achieve greater superplastic properties. In this study twin roll cast (TRC) AZ31 magnesium alloy was subjected to equal channel angular pressing (ECAP) and friction stir welding (FSW). The influence of these severe plastic deformation processes on the grain size, texture and grain boundary character distribution was investigated to identify the optimum severe plastic deformation process for the superplastic forming of AZ31.

  3. Comparison of mechanical and microstructural properties of conventional and severe plastic deformation processes

    Szombathelyi, V.; Krallics, Gy

    2014-08-01

    The effect of the deformation processes on yield stress, Vickers microhardness and dislocation density were investigated using commercial purity (A1050) and alloyed aluminum (Al 6082). For the evolution of the dislocation density X-ray line profile analysis was used. In the large plastic strain range the variation of mechanical and microstructure evolution of A1050 and of Al 6082 processed by equal channel angular pressing are investigated using route BC and route C. In the plastic strain range up to 3 plane strain compression test was used to evaluate mechanical properties. The hardness and the yield stress showed a sharp increase after the first pass. In the case of A1050 it was found that the two examined routes has not resulted difference in the flow stress. In the case of Al 6082 the effect of the routes on the yield stress is significant. The present results showed that in the comparable plastic strain range higher yield stress values can be achieved by plane strain compression test than by ECAP.

  4. Dry-sliding tribological properties of ultrafine-grained Ti prepared by severe plastic deformation

    La Peiqing [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Tianshui Road 342, Lanzhou, Gansu 730000 (China)]. E-mail: pqla@ns.lzb.ac.cn; Ma Jiqiang [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Tianshui Road 342, Lanzhou, Gansu 730000 (China); Zhu, Yuntian T. [Materials Science and Technology Division, MS, G755, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Yang Jun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Tianshui Road 342, Lanzhou, Gansu 730000 (China); Liu Weimin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Tianshui Road 342, Lanzhou, Gansu 730000 (China); Xue Qunji [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Tianshui Road 342, Lanzhou, Gansu 730000 (China); Valiev, Ruslan Z. [Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa 450000, K. Marksa 12 (Russian Federation)

    2005-11-15

    This paper reports the tribological properties of ultrafine-grained (UFG) Ti prepared by severe plastic deformation under dry sliding against AISI52100 steel in ambient environment and at varying load and sliding speed. Worn surfaces of the UFG Ti were examined with a scanning electron microscope and X-ray photoelectron spectroscope. It was found that the wear rate of the UFG Ti under dry sliding was of the magnitude of 10{sup -3} mm{sup 3} m{sup -1}, which is lower than that of the annealed coarse-grained (CG) Ti. The wear rate of the UFG Ti increased with the load, while it decreased with the sliding speed. The friction coefficient of the UFG Ti was in the range of 0.45-0.60, slightly lower than that of the CG Ti, and did not change with the load and sliding time after the initial transient period. The friction coefficient increased with increasing sliding speed to a maximum point and then decreased. The wear mechanism of the UFG Ti was micro-ploughing and delamination. The worn surfaces were covered by a TiO{sub 2} layer. These results demonstrated that UFG structures improved the wear resistance but did not significantly affect the friction coefficient of Ti.

  5. Dry-sliding tribological properties of ultrafine-grained Ti prepared by severe plastic deformation

    This paper reports the tribological properties of ultrafine-grained (UFG) Ti prepared by severe plastic deformation under dry sliding against AISI52100 steel in ambient environment and at varying load and sliding speed. Worn surfaces of the UFG Ti were examined with a scanning electron microscope and X-ray photoelectron spectroscope. It was found that the wear rate of the UFG Ti under dry sliding was of the magnitude of 10-3 mm3 m-1, which is lower than that of the annealed coarse-grained (CG) Ti. The wear rate of the UFG Ti increased with the load, while it decreased with the sliding speed. The friction coefficient of the UFG Ti was in the range of 0.45-0.60, slightly lower than that of the CG Ti, and did not change with the load and sliding time after the initial transient period. The friction coefficient increased with increasing sliding speed to a maximum point and then decreased. The wear mechanism of the UFG Ti was micro-ploughing and delamination. The worn surfaces were covered by a TiO2 layer. These results demonstrated that UFG structures improved the wear resistance but did not significantly affect the friction coefficient of Ti

  6. Processing of ultrafine-grained materials using severe plastic deformation: potential for achieving exceptional properties

    Langdon, T. G.

    2008-12-01

    Full Text Available The processing of polycrystalline metals through the application of severe plastic deformation is attracting much attention because of the potential for achieving significant grain refinement to the submicrometer or nanometer level. This paper reviews the principles of this type of processing with emphasis on two different techniques: Equal- Channel Angular Pressing and High-Pressure Torsion. Exceptional properties may be achieved from these processes including high strength at ambient temperatures and a rapid superplastic forming capability at elevated temperatures. Some examples are presented demonstrating the potential use of this type of processing.

    El procesado de metales policristalinos a través de deformación plástica severa está atrayendo mucha atención, debido al potencial para alcanzar un importante afino de grano a niveles submicrométricos o nanométricos. Esta publicación revisa los principios de este tipo de procesado haciendo hincapié en dos técnicas diferentes: prensado en canal angular y torsión bajo alta presión. Mediante estos procesos, se pueden alcanzar propiedades excepcionales incluyendo alta resistencia a temperatura ambiente y una capacidad de conformación superplástica rápida a elevadas temperaturas. Se presentan algunos ejemplos demostrando el uso potencial de este tipo de procesado.

  7. The effects of severe plastic deformation on some properties relevant to Ti implants

    Anibal Andrade, Mendes Filho; Vitor Luiz, Sordi; Maurizio, Ferrante.

    2012-02-01

    Full Text Available In some types of surgical implants, such as bone screws and plates, Grade 2 Ti is seriously considered as a replacement for the Ti-6Al-4V alloy. Advantages are lower cost and the absence of Al and V, which have been identified as potentially harmful to human health. The present paper shows that the [...] lower strength of the commercially pure metal can be enhanced by Severe Plastic Deformation followed by conventional cold rolling, so as to reach a strength level higher than the technical requirements applicable to the alloy. This was ascertained by tensile and Vickers hardness tests from which it was concluded that the best combination of properties are obtained by submitting the metal to Equal Channel Angular Pressing (four passes at 300 C) followed by a 70% thickness reduction by cold rolling. Although the present results are valid for the material only, and not for the product considered, that is, bone screws, it appears that this solution is a step towards the replacement of the Ti6-4 alloy by Grade 2 Ti, at least for some types of metallic medical implants.

  8. The effects of severe plastic deformation on some properties relevant to Ti implants

    Anibal Andrade Mendes Filho

    2012-02-01

    Full Text Available In some types of surgical implants, such as bone screws and plates, Grade 2 Ti is seriously considered as a replacement for the Ti-6Al-4V alloy. Advantages are lower cost and the absence of Al and V, which have been identified as potentially harmful to human health. The present paper shows that the lower strength of the commercially pure metal can be enhanced by Severe Plastic Deformation followed by conventional cold rolling, so as to reach a strength level higher than the technical requirements applicable to the alloy. This was ascertained by tensile and Vickers hardness tests from which it was concluded that the best combination of properties are obtained by submitting the metal to Equal Channel Angular Pressing (four passes at 300 C followed by a 70% thickness reduction by cold rolling. Although the present results are valid for the material only, and not for the product considered, that is, bone screws, it appears that this solution is a step towards the replacement of the Ti6-4 alloy by Grade 2 Ti, at least for some types of metallic medical implants.

  9. Anharmonicity of the excited octupole band in actinides using supersymmetric quantum mechanics

    Jolos, R. V.; von Brentano, P.; Casten, R. F.

    2013-09-01

    Background: Low-lying octupole collective excitations play an important role in the description of the structure of nuclei in the actinide region. Ground state alternating parity rotational bands combining both positive and negative parity states are known in several nuclei. However, only recently it has been discovered in 240Pu an excited positive parity rotational band having an octupole nature and demonstrating strong anharmonicity of the octupole motion in the band head energies.Purpose: To suggest a model describing both ground state and excited alternating parity bands, which includes a description of the anharmonic effects in the bandhead excitation energies and can be used to predict the energies of the excited rotational bands of octupole nature and the E1 transition probabilities.Methods: The mathematical technique of the supersymmetric quantum mechanics with a collective Hamiltonian depending only on the octupole collective variable which keeps axial symmetry is used to describe the ground state and excited alternating parity rotational bands.Results: The excitation energies of the states belonging to the lowest negative parity and the excited positive parity bands are calculated for 232Th, 238U, and 240Pu. The E1 transition matrix elements are also calculated for 240Pu.Conclusions: It is shown that the suggested model describes the excitation energies of the states of the lowest negative parity band with the accuracy around 10 keV. The anharmonicity in the bandhead energy of the excited positive parity band is described also. The bandhead energy of the excited positive parity band is described with the accuracy around 100 keV.

  10. Studying physical properties of deformed intact and fractured rocks by micro-scale hydro-mechanical-seismicity model

    Raziperchikolaee, Samin

    The pore pressure variation in an underground formation during hydraulic stimulation of low permeability formations or CO2 sequestration into saline aquifers can induce microseismicity due to fracture generation or pre-existing fracture activation. While the analysis of microseismic data mainly focuses on mapping the location of fractures, the seismic waves generated by the microseismic events also contain information for understanding of fracture mechanisms based on microseismic source analysis. We developed a micro-scale geomechanics, fluid-flow and seismic model that can predict transport and seismic source behavior during rock failure. This model features the incorporation of microseismic source analysis in fractured and intact rock transport properties during possible rock damage and failure. The modeling method considers comprehensive grains and cements interaction through a bonded-particle-model. As a result of grain deformation and microcrack development in the rock sample, forces and displacements in the grains involved in the bond breakage are measured to determine seismic moment tensor. In addition, geometric description of the complex pore structure is regenerated to predict fluid flow behavior of fractured samples. Numerical experiments are conducted for different intact and fractured digital rock samples, representing various mechanical behaviors of rocks and fracture surface properties, to consider their roles on seismic and transport properties of rocks during deformation. Studying rock deformation in detail provides an opportunity to understand the relationship between source mechanism of microseismic events and transport properties of damaged rocks to have a better characterizing of fluid flow behavior in subsurface formations.

  11. Quantitative genetic properties of four measures of deformity in yellowtail kingfish Seriola lalandi Valenciennes, 1833.

    Nguyen, N H; Whatmore, P; Miller, A; Knibb, W

    2016-02-01

    The main aim of this study was to estimate the heritability for four measures of deformity and their genetic associations with growth (body weight and length), carcass (fillet weight and yield) and flesh-quality (fillet fat content) traits in yellowtail kingfish Seriola lalandi. The observed major deformities included lower jaw, nasal erosion, deformed operculum and skinny fish on 480 individuals from 22 families at Clean Seas Tuna Ltd. They were typically recorded as binary traits (presence or absence) and were analysed separately by both threshold generalized models and standard animal mixed models. Consistency of the models was evaluated by calculating simple Pearson correlation of breeding values of full-sib families for jaw deformity. Genetic and phenotypic correlations among traits were estimated using a multitrait linear mixed model in ASReml. Both threshold and linear mixed model analysis showed that there is additive genetic variation in the four measures of deformity, with the estimates of heritability obtained from the former (threshold) models on liability scale ranging from 0.14 to 0.66 (SE 0.32-0.56) and from the latter (linear animal and sire) models on original (observed) scale, 0.01-0.23 (SE 0.03-0.16). When the estimates on the underlying liability were transformed to the observed scale (0, 1), they were generally consistent between threshold and linear mixed models. Phenotypic correlations among deformity traits were weak (close to zero). The genetic correlations among deformity traits were not significantly different from zero. Body weight and fillet carcass showed significant positive genetic correlations with jaw deformity (0.75 and 0.95, respectively). Genetic correlation between body weight and operculum was negative (-0.51, P < 0.05). The genetic correlations' estimates of body and carcass traits with other deformity were not significant due to their relatively high standard errors. Our results showed that there are prospects for genetic selection to improve deformity in yellowtail kingfish and that measures of deformity should be included in the recording scheme, breeding objectives and selection index in practical selective breeding programmes due to the antagonistic genetic correlations of deformed jaws with body and carcass performance. PMID:25683477

  12. Microstructure, mechanical properties, deformation, and fracture of V-4Ti-4Cr alloys

    Full text of publication follows: The effect of the mode of thermomechanical treatment (TMT) on the microstructure, mechanical properties, mechanisms of plastic deformation, and fracture of V-4Ti-4Cr alloys has been studied. For these alloys, the TMT modes that provide a volumetrically uniform distribution of superfine particles of oxy-carbonitride phases, a substantial growth of their density, and an increase in recrystallization temperature have been substantiated. Interrelations have been found between the microstructure of the alloys and the features of their mechanical behavior, such as the level of strength and plasticity, discontinuous yielding, and an abnormal temperature dependence of strength. It has been shown that these phenomena are underlined by the high thermodynamic instability of the V-4Ti-4Cr alloys after TMT which is due to the presence of supersaturated solid solutions of titanium with interstitial elements, local inhomogeneities in composition, and superfine particles of oxy-carbonitride phases. The great variety of thermally activated obstacles that appear during TMT and mechanical tests at elevated temperatures are responsible for the significantly extended range of the anomalous temperature dependence of yield strength and the conservation of high values of strength up to T ≅850 deg. C. The phenomenon of strain localization has been revealed whose temperature range coincides with the range of discontinuous yielding. The conclusion has been made that this phenomenon can be a direct reason for the discontinuous yielding that testifies to local mechanical instabilities in strain localization bands. Analysis of possible mechanisms and important features of the structural and stream instabilities of plastic flow in these bands has been performed. The TMT modes have been substantiated that provide high thermal stability of the microstructure and a significant increase in short-time strength of the V-4Ti-4Cr alloys over a wide temperature range (from 20 to 1000 deg. C), leaving rather much margin for plasticity. (authors)

  13. Dependence of the powder nickel alloy mechanical properties on the deformation temperature and rate

    Nickel superalloy of ZhS6 type has been studied. Being obtained by conventional casting this alloy cannot be subjected to deformation because of extremely low plasticity. It has been determined that the strength and plasticity of the cast nickel alloy obtained by the method of granule metallurgy at indoor temperature are 1.5 and 3.4 times as high , respectively, than those of the alloy obtained by conventional casting. It has been shown that at temperatures of 1000-1150 deg C the powder alloy shows the superplasticity effect: at low deformation rates its elongation reaches some hundreds per cent with loadings of about 0.1?sub(0.2); a relative elongation of the sample, the value of the applied loading and the deformation diagram type depend to a considerable extent on the deformation rate; with its decrease ?sub(k) sharply increases and the loading decreases

  14. Thermo-mechanical properties of a deformable mirror with screen printed actuator

    Bruchmann, C.; Appelfelder, M.; Beckert, E.; Eberhardt, R.; Tünnermann, A.

    2012-03-01

    This paper reports on the thermo-mechanical modeling and characterization of a screen printed deformable mirror. The unimorph mirror offers a ceramic LTCC substrate with screen printed PZT layers on its rear surface and a machined copper layer on its front surface. We present the thermo-mechanical model of the deformable mirror based on Ansys multiphysics. The developed mirror design is practically characterized. The homogeneous loading of the optimized design results in a membrane deformation with a rate of -0.2 μm/K, while a laser loading causes a change with a rate of 1.3 μm/W. The proposed mirror design is also suitable to pre-compensate laser generated mirror deformations by homogeneous thermal loading (heating). We experimentally show that a 35 K pre-heating of the mirror assembly could compensate an absorbed laser power of 1.25 W.

  15. Effect of plastic deformation of a quenched maraging steel on its mechanical properties

    The after quenching effect of plastic deformation on structural strength and operation reliability of N17K12M5T ssheet maraging steel was investigated. It was determined that after double quenching and before aging plastic deformation positively affected structural strength characteristics, in particular, strength limit of fractured samples, creep-rupture strength during the test on slow destructuon in water, corrosion under stress and stress intensity coefficient

  16. Cyclis deformation properties of 15Kh2MFA material for reactor pressure vessels

    The limit service life curves were determined for steel 15Kh2MFA undergoing low-cycle and high-cycle fatigue, respectively. Low-cycle stress results in reducing the steel strength. Good agreement was found of the limit curve obtained for stress with constant Δepsilon with a limit curve as specified by ASME. The cyclic deformation curve was determined using two different techniques. In stress with constant force, plastic deformation increases in form of cyclic creep, this also in steels. The independence of service life of the mean deformation at stress with constant Δepsilon was also tested. At normal temperatures, a reduced loading rate from 0.2 Hz to 0.0009 Hz and a delay in the maximum deformation in a cycle reduces the average service life of steel 15Kh2MFA by about 30%. One alternating cycle with a constant of Δepsilon=8x10-3 reduces the average high-cycle fatigue 2.4 times, a hundred previous cycles of alternating deformation Δepsilon=8x10-3 more than 5 times. Elevated temperature to up to 350 degC does not significantly affect the service life of alloyed steel in low-cycle fatigue. The elevated temperature affects more significantly the cyclic deformation curve. Neutron flux irradiation of alloyed steel did not significantly affect the service life after low-cycle fatigue. (B.S.)

  17. Oxide dispersion strengthened ferritic alloys. 14/20% chromium: effects of processing on deformation texture, recrystallization and tensile properties

    The ferritic oxide dispersion strengthened alloys are promising candidates for high temperature application materials, in particular for long life core components of advanced nuclear reactors. The aim of this work is to control the microstructure, in order to optimise the mechanical properties. The two ferritic alloys examined here, MA956 and MA957, are obtained by Mechanical Alloying techniques. They are characterised by quite anisotropic microstructure and mechanical properties. We have investigated the influence of hot and cold working processes (hot extrusion, swaging and cold-drawing) and recrystallization heat treatments on deformation textures, microstructures and tensile properties. The aim was to control the size of the grains and their anisotropic shape, using recrystallization heat treatments. After consolidation and hot extrusion, as-received materials present a extremely fine microstructure with elongated grains and a very strong (110) deformation texture with single-crystal character. At that stage of processing, recrystallization temperature are very high (1450 degrees C for MA957 alloy and 1350 degrees C for MA956 alloy) and materials develop millimetric recrystallized grains. Additional hot extrusion induce a fibre texture. Cold-drawing maintains a fibre texture, but the intensity decreases with increasing cold-work level. For both materials, the decrease of texture intensities correspond to a decrease of the recrystallization temperatures (from 1350 degrees C for a low cold-work level to 750 degrees C for 60 % cold-deformation, case of MA956 alloy) and a refinement of the grain size (from a millimetric size to less than an hundred of micrometer). Swaging develop a cyclic component where the intensity increases with increasing deformation in this case, the recrystallization temperature remains always very high and the millimetric grain size is slightly modified, even though cold-work level increases. Technologically, cold-drawing is the only way that permits the decreasing of the recrystallization temperature of several hundred degrees and giving the best compromise between mechanical strength and ductility. (author). 72 refs., 6 appends

  18. Octupole excitations in vibrational nuclei and the sdf interacting boson model

    Proton and deuteron inelastic scattering experiments, performed with an energy resolution of 12-15 keV, have been used to study negative-parity states of vibrational and transitional nuclei with mass between 98 and 150. The analysis has been focussed on the isovector components, on the quadrupole-octupole two-phonon states and on the fragmentation of the octupole strength. This latter displays a regular dependence on the product of proton and neutron valence particle numbers and is satisfactorily reproduced by IBM-1+f-boson calculations. Other features of the experimental spectra, as the relative positions of the 3- states, exhibit a dependence on the ratio of valence particle numbers and indicate that a IBM-2 approach might be more appropriate. (orig.)

  19. Spin-controlled octupole-shape transition in 224Ra: a microscopic description

    Yao, J M; Li, Z P

    2015-01-01

    We report the first beyond-mean-field study of low-lying parity-doublet states in 224Ra by extending the multireference relativistic energy density functional method to include dynamical correlations related to symmetry restoration and quadrupole-octupole shape fluctuation with a generator coordinate method combined with parity, particle-number, and angular-momentum projections. We clarify full microscopically that there is a novel spin-controlled phase transition from dynamical octupole shapes to a stable one, where the dominated shape of positive-parity states drifts gradually to that of negative-parity states. This transition is characterized by the gradually reduced odd-even staggering in the excitation energies of parity doublets when approaching the transition from below.

  20. Lower hybrid heating associated with mode conversion on the Wisconsin octupole

    This thesis addresses the following key issues in the lower hybrid frequency range: 1. What are the importent physics aspects of wave propagation and heating in an experimental situation. 2. How effective is plasma heating in the complex magnetic field configuration of the octupole. Experimental work is accomplished by launching 1-10ms pulses of up to 40kW of radio frequency power at 140MHz corresponding to the hot plasma lower hybrid resonance in the octupole. A diploe antenna which is moveable radially and is also rotatable couples wave power to the plasma. Coupling efficiencies greater than 95% are achieved by proper antenna placement near the edge of the plasma radial density profile

  1. Lower hybrid heating associated with mode conversion on the Wisconsin octupole

    Owens, T.L.

    1979-08-01

    This thesis addresses the following key issues in the lower hybrid frequency range: 1. What are the importent physics aspects of wave propagation and heating in an experimental situation. 2. How effective is plasma heating in the complex magnetic field configuration of the octupole. Experimental work is accomplished by launching 1-10ms pulses of up to 40kW of radio frequency power at 140MHz corresponding to the hot plasma lower hybrid resonance in the octupole. A diploe antenna which is moveable radially and is also rotatable couples wave power to the plasma. Coupling efficiencies greater than 95% are achieved by proper antenna placement near the edge of the plasma radial density profile.

  2. Mixed-symmetry octupole and hexadecapole excitations in the N=52 isotones

    Hennig, A; Werner, V; Ahn, T; Anagnostatou, V; Cooper, N; Derya, V; Elvers, M; Endres, J; Goddard, P; Heinz, A; Huges, R O; Ilie, G; Mineva, M N; Petkov, P; Pickstone, S G; Pietralla, N; Radeck, D; Ross, T J; Savran, D; Zilges, A

    2015-01-01

    Background: Excitations with mixed proton-neutron symmetry have been previously observed in the $N=52$ isotones. Besides the well established quadrupole mixed-symmetry states (MSS), octupole and hexadecapole MSS have been recently proposed for the nuclei $^{92}$Zr and $^{94}$Mo. Purpose: The heaviest stable $N=52$ isotone $^{96}$Ru was investigated to study the evolution of octupole and hexadecapole MSS with increasing proton number. Methods: Two inelastic proton-scattering experiments on $^{96}$Ru were performed to extract branching ratios, multipole mixing ratios, and level lifetimes. From the combined data, absolute transition strengths were calculated. Results: Strong $M1$ transitions between the lowest-lying $3^-$ and $4^+$ states were observed, providing evidence for a one-phonon mixed-symmetry character of the $3^{(-)}_2$ and $4^+_2$ states. Conclusions: $sdg$-IBM-2 calculations were performed for $^{96}$Ru. The results are in excellent agreement with the experimental data, pointing out a one-phonon he...

  3. Hyperfine-induced electric dipole contributions to the electric octupole and magnetic quadrupole atomic clock transitions

    Dzuba, V A

    2016-01-01

    Hyperfine-induced electric dipole contributions may significantly increase probabilities of otherwise very weak electric octupole and magnetic quadrupole atomic clock transitions (e.g. transitions between $s$ and $f$ electron orbitals). These transitions can be used for exceptionally accurate atomic clocks, quantum information processing and search for dark matter. They are very sensitive to new physics beyond the Standard Model, such as temporal variation of the fine structure constant, the Lorentz invariance and Einstein equivalence principle violation. We formulate conditions under which the hyperfine-induced electric dipole contribution dominates. Due to the hyperfine quenching the electric octupole clock transition in $^{173}$Yb$^+$ is two orders of magnitude stronger than that in currently used $^{171}$Yb$^+$. Some enhancement is found in $^{143}$Nd$^{13+}$, $^{149}$Pm$^{14+}$, $^{147}$Sm$^{14+}$, and $^{147}$Sm$^{15+}$ ions.

  4. Measurements of octupole collectivity in Rn and Ra nuclei using Coulomb excitation

    We propose to exploit the unique capability of HIE-ISOLDE to provide post-accelerated $^{221,222}$Rn and $^{222,226,228}$Ra ion beams for the study of octupole collectivity in these nuclei. We will measure E3 transition moments in $^{222}$Rn and $^{222,226,228}$Ra in order to fully map out the variation in E3 strengh in the octupole mass region with Z$\\thicksim$88 and N$\\thicksim$134. This will validate model calculations that predict different behaviour as a function of N. We will also locate the position of the parity doublet partner of the ground state in $^{221}$Rn, in order to test the suitability of odd-A radon isotopes for EDM searches.

  5. Deformation and energy absorption properties of powder-metallurgy produced Al foams

    Highlights: ? Porous Al fabricated via a dissolution and sintering method using raw cane sugar. ? Different deformation mode depending on the relative density of the foams. ? Enhanced energy absorption by reducing pore size and relative density of the foam. ? Pore size uniformity and sintering temperature affect energy absorption. - Abstract: Al-foams with relative densities ranging from 0.30 to 0.60 and mean pore sizes of 0.35, 0.70 and 1.35 mm were manufactured by a powder metallurgy technology, based on raw cane sugar as a space-holder material. Compressive tests were carried out to investigate the deformation and energy absorbing characteristics and mechanisms of the produced Al-foams. The deformation mode of low density Al-foams is dominated by the bending and buckling of cell walls and the formation of macroscopic deformation bands whereas that of high density Al-foams is predominantly attributed to plastic yielding. The energy absorbing capacity of Al-foams rises for increased relative density and compressive strength. The sintering temperature of Al-foams having similar relative densities has a marked influence on both, energy absorbing efficiency and capacity. Pore size has a marginal effect on energy efficiency aside from Al-foams with mean pore size of 0.35 which exhibit enhanced energy absorption as a result of increased friction during deformation at lower strain levels.

  6. Mechanical properties and local mobility of atactic-polystyrene films under constant-shear deformation.

    Hudzinskyy, D; Michels, M A J; Lyulin, A V

    2012-09-28

    We have performed molecular-dynamics simulations of atactic polystyrene thin films to study the effect of shear rate, pressure, and temperature on the stress-strain behaviour, the relevant energetic contributions and non-affine displacements of polymer chains during constant-shear deformation. Under this deformation sliding motion is observed at high shear rates between the top substrate and top polymer layer, which disappears when the shear rate decreases. At low shear rates stick-slip motion of the whole film with respect to the bottom substrate takes place. We found that at low shear rates the yield stress logarithmically depends on the shear rate; this behaviour can be explained in terms of the Eyring model. It was also observed that an increase in the normal pressure leads to an increase in the yield stress in agreement with experiments. The contributions to the total shear stress and energy are mainly given by the excluded-volume interactions. It corresponds to a local translational dynamics under constant shear in which particles are forced to leave their original cages much earlier as compared to the case of the isotropic, non-sheared film. Moreover, it was observed that under constant-shear deformation the polymer glass is deformed non-affinely. As a result, the middle part of the film is much more deformed than the layers close to the supporting substrates, meaning that the well-known effect of shear-banding occurs. PMID:23020347

  7. Relative spins and excitation energies of superdeformed bands in 190Hg: Further evidence for octupole vibration

    An experiment using the Eurogam phase II ?-ray spectrometer confirms the existence of an excited superdeformed (SD) band in 190Hg and its very unusual decay into the lowest SD band over 3--4 transitions. The energies of the transitions linking the two SD bands have been firmly established, and their angular distributions are consistent with a dipole character. Comparisons with calculations using random-phase approximation indicate that the excited SD band can be interpreted as an octupole-vibrational structure

  8. Progress Towards A Permanent Octupole Magnetic Ultra-Cold Neutron Trap for Lifetime Measurements

    Leung, Kent; Zimmer, Oliver

    2008-01-01

    The current knowledge of the neutron $\\beta$-decay lifetime has come under scrutiny as of late due to large disagreements between recent precise measurements. Measurements using magnetically trapped Ultra-Cold Neutrons (UCNs) offer the possibility of storage without spurious losses which can provide a reliable value for the neutron lifetime. The progress towards realizing a neutron lifetime measurement using a Ioffe-type trap made with a Halbach-type permanent octupole magnet is presented her...

  9. Relative spins and excitation energies of superdeformed bands in $^{190}$Hg further evidence for octupole vibration

    Crowell, B; Janssens, R V F; Blumenthal, D J; Wilson, A N; Sharpey-Schafer, J F; Nakatsukasa, T; Ahmad, I; Astier, A; Azaiez, F; Du Croix, L; Gall, B J P; Hannachi, F; Khoo, T L; Korichi, A; Lauritsen, T; Lpez-Martens, A; Meyer, M R; Nisius, D; Paul, E S; Porquet, M G; Redon, N; Crowell, B; Carpenter, M P; Janssens, R V F; Blumenthal, D J; Wilson, A N; Sharpey-Schafer, J F; Nakatsukasa, T; du Croux, L; Gall, B J P; Hannachi, F; Khoo, T L; Korichi, A; Lauritsen, T; Lopez-Martens, A; Meyer, M; Nisius, D; Paul, E S; Porquet, M G; Redon, N

    1994-01-01

    An experiment using the Eurogam Phase II gamma-ray spectrometer confirms the existence of an excited superdeformed (SD) band in 190Hg and its very unusual decay into the lowest SD band over 3-4 transitions. The energies and dipole character of the transitions linking the two SD bands have been firmly established. Comparisons with RPA calculations indicate that the excited SD band can be interpreted as an octupole-vibrational structure.

  10. Mixed-symmetry octupole and hexadecapole excitations in N=52 isotones

    Hennig, Andreas; Spieker, Mark; Werner, Volker; Ahn, Tan; Anagnostatou, Vassia; Cooper, Nathan; Derya, Vera; Elvers, Michael; Endres, Janis; Goddard, Phil; Heinz, Andreas; Hughes, Richard O.; Ilie, Gabriela; Mineva, Milena N.; Pickstone, Simon G.; Petkov, Pavel; Pietralla, Norbert; Radeck, Desire; Ross, Tim J.; Savran, Deniz; Zilges, Andreas

    2015-05-01

    In addition to the well-established quadrupole mixed-symmetry states, octupole and hexadecapole excitations with mixed-symmetry character have been recently proposed for the N = 52 isotones 92Zr and 94Mo. We performed two inelastic proton-scattering experiments to study this kind of excitations in the heaviest stable N = 52 isotone 96Ru. From the combined experimental data of both experiments absolute transition strengths were extracted.

  11. Mixed-symmetry octupole and hexadecapole excitations in N=52 isotones

    Hennig Andreas

    2015-01-01

    Full Text Available In addition to the well-established quadrupole mixed-symmetry states, octupole and hexadecapole excitations with mixed-symmetry character have been recently proposed for the N = 52 isotones 92Zr and 94Mo. We performed two inelastic proton-scattering experiments to study this kind of excitations in the heaviest stable N = 52 isotone 96Ru. From the combined experimental data of both experiments absolute transition strengths were extracted.

  12. Characterization of properties in plastically deformed austenitic-stainless steels joined by friction welding

    Friction welding is widely used as a mass-production method in various industries. Welding is used for joining parts with equal and/or different diameters. Austenitic-stainless steels are preferred over other stainless steels due greater ease in welding. In the present study, an experimental set-up was designed in order to achieve friction welding of plastically deformed austenitic-stainless steels. AISI 304 austenitic-stainless steels having equal and different diameters were welded under different process parameters. Strengths of the joints having equal diameter were determined by using a statistical approach as a result of tension tests. Hardness variations and microstructures using scanning electron microscope (SEM) analysis in the welding zone were obtained and examined. Subsequently, the effects on the welding zone of plastic deformation was analysed. It has been established that plastic deformation of AISI 304 austenitic-stainless steel has neither an effect on the process nor on the strength of the welding joint

  13. Characterization of properties in plastically deformed austenitic-stainless steels joined by friction welding

    Sahin, Mumin [Mechanical Engineering Department, Engineering and Architecture Faculty, Trakya University, 22180 Edirne (Turkey)], E-mail: mumins@trakya.edu.tr

    2009-01-15

    Friction welding is widely used as a mass-production method in various industries. Welding is used for joining parts with equal and/or different diameters. Austenitic-stainless steels are preferred over other stainless steels due greater ease in welding. In the present study, an experimental set-up was designed in order to achieve friction welding of plastically deformed austenitic-stainless steels. AISI 304 austenitic-stainless steels having equal and different diameters were welded under different process parameters. Strengths of the joints having equal diameter were determined by using a statistical approach as a result of tension tests. Hardness variations and microstructures using scanning electron microscope (SEM) analysis in the welding zone were obtained and examined. Subsequently, the effects on the welding zone of plastic deformation was analysed. It has been established that plastic deformation of AISI 304 austenitic-stainless steel has neither an effect on the process nor on the strength of the welding joint.

  14. Influence of plastic deformation on superconducting properties of V3Si single crystals

    Effects of the plastic deformation at elevated temperatures on the critical parameters Tsub(c) and jsub(c) of V3Si single crystals are reported. Plastic deformation can increase as well as decrease the critical temperature. The sign of the change in Tsub(c) can be attributed to different available point defect types on both sides from stoichiometry. In samples with excess V a decrease in Tsub(c) is observed combined with an increase of the electrical resistivity ratio r. The transition becomes broader and the critical current density increases with the deformation. In samples with excess Si the critical temperature is found to be increased as r decreases, at the same time the critical current density is lowered. (author)

  15. Cold deformation effect on the microstructures and mechanical properties of AISI 301LN and 316L stainless steels

    As austenitic stainless steels have an adequate combination of mechanical resistance, conformability and resistance to corrosion they are used in a wide variety of industries, such as the food, transport, nuclear and petrochemical industries. Among these austenitic steels, the AISI 301LN and 316L steels have attracted prominent attention due to their excellent mechanical resistance. In this paper a microstructural characterization of AISI 301LN and 316L steels was made using various techniques such as metallography, optical microscopy, scanning electronic microscopy and atomic force microscopy, in order to analyze the cold deformation effect. Also, the microstructural changes were correlated with the alterations of mechanical properties of the materials under study. One of the numerous uses of AISI 301LN and 316L steels is in the structure of wagons for metropolitan surface trains. For this type of application it is imperative to know their microstructural behavior when subjected to cold deformation and correlate it with their mechanical properties and resistance to corrosion. Microstructural analysis showed that cold deformation causes significant microstructural modifications in these steels, mainly hardening. This modification increases the mechanical resistance of the materials appropriately for their foreseen application. Nonetheless, the materials become susceptible to pitting corrosion.

  16. Steel Processing Properties and Their Effect on Impact Deformation of Lightweight Structures

    Simunovic, S

    2003-09-23

    The objective of the research was to perform a comprehensive computational analysis of the effects of material and process modeling approaches on performance of UltraLight Steel Auto Body (ULSAB) vehicle models. The research addressed numerous material related effects, impact conditions as well as analyzed the performance of the ULSAB vehicles in crashes against designs representing the current US vehicle fleet. This report is organized into three main sections. The first section describes the results of the computational analysis of ULSAB crash simulations that were performed using advanced material modeling techniques. The effects of strain-rate sensitivity on a high strength steel (HSS) intensive vehicle were analyzed. Frontal and frontal offset crash scenarios were used in a finite element parametric study of the ULSAB body structure. Comparisons are made between the crash results using the piece-wise-linear isotropic plasticity strain-rate dependent material model, and the isotropic plasticity material model based on quasi-static properties. The simulation results show the importance of advanced material modeling techniques for vehicle crash simulations due to strain-rate sensitivity and rapid hardening characteristics of advanced high strength steels. Material substitution was investigated for the main frontal crush structure using the material of similar yield stress a significantly different strain-rate and hardening characteristics. The objective of the research presented in Section 2 was to assess the influence of stamping process on crash response of ULSAB vehicle. Considered forming effects included thickness variations and plastic strain hardening imparted in the part forming process. The as-formed thickness and plastic strain for front crash parts were used as input data for vehicle crash analysis. Differences in structural performance between crash models with and without forming data were analyzed in order to determine the effects and feasibility of integration of forming processes and crash models. Computational analysis of vehicle-to-vehicle crashes between ULSAB and conventional car designs is reported in Section 3. The study involved vehicles of comparable weights and dimensions to assess the compatibility of the ULSAB with existing designs. Deformation and acceleration data for crashed vehicles were analyzed. Vehicle-modeling approaches have strong influence on computational results and the requirements for compatibility of models were identified for future research on vehicle-to-vehicle crash modeling.

  17. Deformation and Fracture Properties in Neutron Irradiated Pure Mo and Mo Alloys

    Byun, T.S.; Snead, L. [ORNL, Oak Ridge National Laboratory, Bldg. 9201-2, MS-8072, Oak Ridge, Tennessee, TN 37831-8072 (United States); Li, M. [Oak Ridge Noational Laboratory, PO 2008, MS 6138, Oak Ridge, TN 37931-6138 (United States); Cockeram, B.V. [Bettis Atomic Power Laboratory, West Mifflin, AK PA 15122 (United States)

    2007-07-01

    Full text of publication follows: The evolution in microstructural and mechanical properties was investigated for molybdenum and molybdenum alloys after high temperature neutron irradiation. Test materials include oxide dispersion-strengthened (ODS) molybdenum alloy, molybdenum- 0.5% titanium-0.1% zirconium (TZM) alloy, and low carbon arc-cast (LCAC) molybdenum. Tensile specimens were irradiated in high flux isotope reactor (HFIR) at temperatures in the range {approx}300 - 1000 deg. C to neutron fluences of 2.28 - 24.7 x 10{sup 25} n/m{sup 2} (E>0.1 MeV) or 1.2-13.1 dpa. Tensile tests were performed at temperatures ranging from -150 deg. C to 1000 deg. C. To evaluate irradiation effects, true stress parameters (yield stress, plastic instability stress, and true fracture stress) and ductility parameters (uniform strain, fracture strain, and reduction area) were compared for both irradiated and non-irradiated materials. Fracture toughness was also evaluated from the fracture stress and fracture strain data using a fracture strain model. The fracture strain was used to determine the ductile-to-brittle transition temperature (DBTT). Results indicate that irradiation in the temperature range of 600 - 800 deg. C hardened the materials by up to 70%, while the irradiation hardening outside this temperature range was much lower (<40%). The plastic instability stress was strongly dependent on test temperature; however, it was nearly independent of irradiation dose and temperature. It was also found that the true fracture stress was dependent on test temperature. The true fracture stress was not significantly influenced by irradiation at elevated and high test temperatures; however, it was decreased significantly at sub-zero temperatures after irradiation due to material embrittlement. The DBTT for 600 deg. C irradiated ODS molybdenum alloy was found to be about room temperature or lower, and among the test materials the ODS alloy showed the highest resistance to irradiation embrittlement. The as-irradiated and deformed microstructures were characterized by TEM and compared to explain the high toughness behavior of the ODS alloy. (authors)

  18. Mica, deformation fabrics and the seismic properties of the continental crust

    Lloyd, Geoffrey E.; Butler, Robert W. H.; Casey, Martin; Mainprice, David

    2009-10-01

    Seismic anisotropy originating within the continental crust is used to determine kinematic flow lines within active mountain belts and is widely attributed to regionally aligned mica. However, naturally deformed micaceous rocks commonly show composite (e.g. S-C) fabrics. It is necessary therefore to understand how both varying mica content and differing intensities of multiple foliations impact on seismic interpretations in terms of deformation fields. An outcrop analogue for granitic mid-crustal deformed zones is used here to calibrate the seismic response against both parameters. Seismic responses are modelled using crystallographic preferred orientations for polymineralic, micaceous granitic gneisses, measured using Electron Back-Scatter Diffraction. The sample results are generalised by modelling the effects of variations in modal composition and the relative importance of deformation fabrics of variable orientation, so-called rock and fabric recipes. The maximum P- and S-anisotropy are calculated at 16.6% and 23.9% for single-foliation gneisses but for mixed (i.e. S-C) foliation gneisses these values reduce to 5.8% and 7.5% respectively. Furthermore, mixtures of multiple foliations generate significant variations in the geometry of the seismic anisotropy. This effect, coupled with the geographical orientation of fabrics in nature, can generate substantial variations in the orientation and magnitude of seismic anisotropy (especially for shear waves) as measured for the continental crust using existing receiver function and teleseismic near-vertical incidence methods. Thus, maps of seismic anisotropy varying with depth in deforming continents need not imply necessarily depth-varying deformation kinematics and tectonic decoupling.

  19. Tidal deformations of a spinning compact object

    Pani, Paolo; Maselli, Andrea; Ferrari, Valeria

    2015-01-01

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the multipole mom...

  20. The influence of plastic deformation on the structure and properties of high-entropy alloys

    Deformability studied solid solutions high-entropy alloys CrMnFeCoNi2Cu FCC alloys and Ti25Zr25Hf25Nb12,5Ta12,5 BCC structure. It is shown that despite the high strength characteristics as cast these alloys have high technological plasticity. During the deformation occurs in high-entropy alloys nanostructure formation which substantially improves the strength characteristics of the material. Fracture behavior in these alloys is tough fracture, and they have high strength and ductility in the temperature range 273...1123 K

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

    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

  2. Magnetic octupole transitions in odd-mass nuclei

    The reduced probabilities of the M3-transitions in the odd nuclei are studied. The calculations are based on the nucleus quasi-phonon model. The studied states in the deformed nuclei have primarily the single-quasiparticle structure and the B(M3)-values are calculated with an account of the single-quasiparticle and polarization mechanisms. Satisfactory agreement of the theory and experiment is obtained in the 175Yb and 179Hf nuclei. At the same time one cannot yet explain extremely low B(M3)-values in the 179W and 183Pt neutron-deficient nuclides. The calculations in the soft 121Cs and 207Po nuclei are carried out in the assumption, that the states, connected with the M3-transition, have the structure, wherein the components of quasiparticle x phonon type are dominant

  3. Influence of plastic deformation and alloying on magnetic properties and structure of Fe-Mo-Ni base alloys for permanent magnets

    The effect of high degrees of preliminary plastic deformation on hysteresis magnetic properties obtained after annealing is investigated. The effect of gallium additions on magnetic properties of Fe-Mo-Ni alloys is also studied. Plastic deformation with high degrees of reduction (>99%) preceding annealing is found to increase the coercive force of Fe-Mo-Ni alloys. Gallium doping preserves alloy plasticity at increased molybdenum content, that permits to additionally increase the magnetic characteristics

  4. Peculiarities of strength and deformability properties of clay soils in districts of Western Siberia

    Efimenko, Sergey; Efimenko, Vladimir; Sukhorukov, Alexey

    2016-01-01

    The article demonstrates the methodology of the substantiation of the calculated values of moisture, strength, and deformability characteristics of clay subgrade soils for the design of pavements by strength conditions in II, III, and IV road-climatic zones in West Siberia. The main purpose of the work is to ensure the quality of the design of roads in newly developed regions of Russia. To achieve this goal the following problems have been solved: the dislocation of boundary lines of road-climatic zones has been specified, zoning of the investigated territory for the design of roads has been detailed; regularities of changes in strength and deformability characteristics of clay subgrade soils of their moisture have been established; the territorial normalization of the calculated values of moisture, strength, and deformability of clay subgrade soils in relation to the allocated road districts has been carried out. Specification of boundary lines of road-climatic zones has been implemented on the basis of the taxonomic system "zone-subzone-road district". The calculated values of moisture, strength, and deformability characteristics of clay soils, established and differentiated according to road-climatic zones, will ensure the required level of the reliability of transport infrastructure facilities during the life cycle of roads.

  5. Mechanical and electrical properties of blood and evaluation of RBC aggregation and deformability

    Antonova, N.; Říha, Pavel; Ivanov, I.; Gluhcheva, Y.

    Warsaw : International Centre of Biocybernetics (ICB), 2012 - (Bedzinski, R.; Petrtyl, M.), s. 28-32 [Current trends in development of implantable tissue structures. Warsaw (PL), 18.04.2012-20.04.2012] Institutional support: RVO:67985874 Keywords : apparent viscosity * conductivity * dextrans * glutaraldehyde * RBC aggregation * RBC deformability Subject RIV: JB - Sensors, Measurment, Regulation

  6. A physical interpretation for the stability property of a localized disturbance in a deformation flow

    The relationship between the local shape of an unstable disturbance and the basic deformation field has been put forward by Mak and Cai as a general condition for barotropic instability of a zonally varying nondivergent basic flow. The general condition states that an unstable disturbance has to be elongated locally at an angle of less than 45 degrees along the axis of contraction of the basic deformation field. The conventional condition for barotropic instability of a zonally uniform basic flow (an unstable disturbance necessarily leans against the basic shear) is a special case of the general condition. To physically interpret the general condition, we have analyzed the immediate subsequent evolution of a localized elliptic-shaped disturbance (defined in terms of streamfunction) embedded in a purely deformation flow. The localized disturbance has the minimum kinetic energy and enstrophy when its shape is circular. Under the influence of the basic deformation, the disturbance tends to shrink along the axis of contraction and to expand along the axis of dilatation. Hence, the disturbance with the major axis along the axis of contraction would deform toward a circle shape. The change in eccentricity of such a disturbance alone acts to reduce its total energy and enstrophy. Because of the conservation constraint of the total perturbation enstrophy, the amplitude of the disturbance has to increase as its eccentricity decreases. The energy change due to the change in amplitude overwhelms that resulting from the change in eccentricity. Therefore, the overall kinetic energy of the localized disturbance tends to increase with time during the course of its evolution. The same arguments also explain why the disturbance with major axis along the axis of dilatation is decaying. 9 refs., 3 figs

  7. Effect of rolling deformation and solution treatment on microstructure and mechanical properties of a cast duplex stainless steel

    S K Ghosh; D Mahata; R Roychaudhuri; R Mondal

    2012-10-01

    The present study deals with the effect of rolling deformation and solution treatment on the microstructure and mechanical properties of a cast duplex stainless steel. Cast steel reveals acicular/Widmanstätten morphology as well as island of austenite within the -ferrite matrix. Hot rolled samples exhibit the presence of lower volume percent of elongated band of -ferrite (∼40%) and austenite phase which convert into finer and fragmented microstructural constituents after 30% cold deformation. By the solution treatment, the elongated and broken crystalline grains recrystallize which leads to the formation of finer grains (<10 m) of austenite. X-ray diffraction analysis has corroborated well with the above-mentioned microstructural investigation. Enhancement in hardness, yield strength and tensile strength values as well as drop in percent elongation with cold deformation increases its suitability for use in thinner sections. 30% cold rolled and solution treated sample reveals attractive combination of strength and ductility (25.22 GPa%). The examination of fracture surface also substantiates the tensile results. The sub-surface micrographs provide the potential sites for initiation of microvoids.

  8. Scale effects of nanomechanical properties and deformation behavior of Au nanoparticle and thin film using depth sensing nanoindentation

    Dave Maharaj

    2014-06-01

    Full Text Available Nanoscale research of bulk solid surfaces, thin films and micro- and nano-objects has shown that mechanical properties are enhanced at smaller scales. Experimental studies that directly compare local with global deformation are lacking. In this research, spherical Au nanoparticles, 500 nm in diameter and 100 nm thick Au films were selected. Nanoindentation (local deformation and compression tests (global deformation were performed with a nanoindenter using a sharp Berkovich tip and a flat punch, respectively. Data from nanoindentation studies were compared with bulk to study scale effects. Nanoscale hardness of the film was found to be higher than the nanoparticles with both being higher than bulk. Both nanoparticles and film showed increasing hardness for decreasing penetration depth. For the film, creep and strain rate effects were observed. In comparison of nanoindentation and compression tests, more pop-ins during loading were observed during the nanoindentation of nanoparticles. Repeated compression tests of nanoparticles were performed that showed a strain hardening effect and increased pop-ins during subsequent loads.

  9. The effect of microstructure on tensile properties, deformation mechanisms and fracture models of TG6 high temperature titanium alloy

    Research highlights: → Fine α hindered dislocation slip and crack nucleation and decreased crack propagation velocity. → α lamellae decided the type and amount of slip system and the crack propagation. → Fine α lamellae promoted the deformation coordination and the start of new slip systems. → The fracture model of the samples with bimodal microstructure was not sensitive to α lamellae. → Fracture model with the bimodal microstructures was a mixture fracture at room temperature. - Abstract: The tensile properties at room temperature and 600 deg. C of TG6 titanium alloy with different microstructures {bi-modal microstructures with thick α lamella (BTL) and fine α lamella (BFL), and a mixed microstructure with different morphologies of α phase} were obtained. It was found that the BFL microstructure possessed the highest tensile strength, and the elongations of the BTL and BFL microstructures were almost the same of about 13% at room temperature and 17% at 600 deg. C, respectively. In addition, the mixed microstructure had the lowest plasticity. The tensile deformation mechanisms of α lamella (αL), primary α phase (αp), equiaxed α phase (αe) and α colonies were researched by the analysis of respective dislocation morphologies. Notably, the accommodative deformations through grain/phase boundaries sliding determined the deformation models of αL, αp, and αe. Compared to the thick αL and α colony, the fine αL and α colony activated more slip systems due to their excellent accommodative deformation capability. Furthermore the deformation mechanisms at room temperature and 600 deg. C were different from each other. Scanning electron microscope (SEM), energy-dispersive spectrometer (EDS) and transmission electron microscopy (TEM) were used to research the crack propagation paths and fracture models. Crack propagation path crossing α colonies and αp were discussed, respectively. The colonies boundaries, αp/colonies boundaries, αe/αe boundaries and silicide were found to be the stress concentration locations. The micro-plasticity of tensile specimens determined the fracture morphologies and fracture models.

  10. Effect of large deformation pre-loads on the wave properties of hexagonal lattices

    Pal, Raj Kumar; Rimoli, Julian; Ruzzene, Massimo

    2016-05-01

    We study linear wave propagation in nonlinear hexagonal lattices capable of undergoing large deformations, under different levels of pre-load. The lattices are composed of a set of masses connected by linear axial and angular springs, with the nonlinearity arising solely from geometric effects. By applying different levels of pre-load, the small amplitude linear wave propagation response can be varied from isotropic to highly directional. Analytical expressions for the stiffness of a unit cell in the deformed configuration are derived and they are used to analyze the dispersion surfaces and group velocity variation with pre-load. Numerical simulations on finite lattices demonstrate the validity of our unit cell predictions and illustrate the wave steering potential of our lattice.

  11. Severe plastic deformation effect on mechanical properties and substructure of HfO2 nanoparticles bearing copper

    The effect of intense plastic deformation in the course of rolling on the temperature dependence of the ultimate strength of copper containing dispersed HfO2 nanoparticles was studied. The results of thermoactivation analysis of the experimental data showed that the introduction of HfO2 particles did not change the activation energy and, hence, the mechanism of fracture. The presence of dispersed nanoparticles is manifested primarily by an increase in the thermal stability of copper subgrains and their mutual misorientation. This leads to increasing thermal stability of the strength properties. Rolling significantly influences the elastic modulus of the dispersion-strengthened composite

  12. Structure and mechanical behaviour of an aluminium alloy AMg6 after severe plastic deformation and annealing: 2. Mechanical properties

    The peculiarities of the mechanical behavior at the room temperature of the AMg6 industrial aluminium alloy with submicro- and microcrystalline structures, obtained through intensive plastic deformation (IPD) by the equichannel angular pressing and subsequent annealing, are considered. The effect of the structural state on the discontinuous fluidity and characteristics of the alloy static strength, including crack resistance, is analyzed. The conclusion is made, that IPD of the AMg6 alloy increased its tensile properties at the room temperature. The obtained data, however, present no basis for the conclusion on the IPD favorable effect on the alloy plasticity

  13. Microstructure and properties of copper deformed by accumulative roll-bonding

    Núñez Aguilar, Carlota

    2013-01-01

    Accumulative Roll Bonding (ARB), which is a process of severe plastic deformation (SPD), was applied to commercially pure copper 99, 97 % by performing up to 7 ARB cycles at room temperature (RT) conditions without lubrication, at cryogenic temperature (CT) conditions, and high temperature (HT) conditions, respectively. Microstructural characterizations were performed by optical microscopy (OM) and scanning electron microscopy (SEM). Observations revealed that refined grains we...

  14. Deformation induced changes in surface properties of polymers investigated by scanning force microscopy

    Hild, Sabine; Rosa, Armin; Marti, Othmar

    2013-01-01

    In this study the possibility of combining commercial Scanning Force Microscopes (SFM) with stretching devices for the investigation of microscopic surface changes during stepwise elongation is investigated. Different types of stretching devices have been developed either for Scanning Platform-SFM or for Stand Alone-SFM. Their suitability for the investigation of deformation induced surface changes is demonstrated. A uniaxially oriented polypropylene film is stretched vertically to its extrus...

  15. Creation of freestanding wrinkled nano-films with desired deformation properties by controlling the surface morphology of a sacrificial layer

    Hirakata, Hiroyuki; Maruyama, Tomohiro; Yonezu, Akio; Minoshima, Kohji

    2013-05-01

    Various wrinkle patterns can be formed due to the buckling of a stiff thin film on a compliant substrate. However, most wrinkled films previously reported were fixed on a large deformable substrate and thereby the potential deformability of the film was mechanically constrained by the substrate. In this study, we developed a technique for forming various wrinkled structures on the surface of a sacrificial resin layer. Since the sacrificial layer can be subsequently removed with a solvent, freestanding wrinkled films are created using the sacrificial layer. We found that a wrinkled structure is formed on the surface of the layer by applying a compressive strain to the resin layer at the appropriate moment during the hardening process. The wrinkle pattern depends on the curing time and the timing of the straining in two in-plane orthogonal directions. In addition to conventional stripe and labyrinth patterns by simple uniaxial and equi-biaxial strains, respectively, it was found that independent biaxial strains induce interesting structures, such as an orthogonally ordered wrinkle pattern and a nonsymmetrical buckling structure, in which the stripe array produced by the first straining remains and many finer wrinkles appear in each stripe by the second straining in the orthogonal direction. We conducted tensile experiments for 300-nm-thick freestanding Cu films having these wrinkled structures. The wrinkled nano-films have a variety of mechanical properties: the stripe structure has extremely high deformability (more than 10% strain) and reversibility, the labyrinth structure shows planar isotropic deformation, and the nonsymmetrical buckling structure has an anisotropic modulus and strength. Finite element analysis on the wrinkle structures revealed that the local stress concentration dominates the fracture limits.

  16. Reduced electric-octupole transition probabilities, B(E3;O1+ → 31-), for even-even nuclides throughout the periodic table

    Adopted values for the excitation energy, Ex(31-), of the first 3- state of the even-even nuclei are tabulated. Values of the reduced electric-octupole transition probability, B(E3;O1+ → 31-), from the ground state to this state, as determined from Coulomb excitation, lifetime measurements, inelastic electron scattering, deformation parameters β3 obtained from angular distributions of inelastically scattered nucleons and light ions, and other miscellaneous procedures are listed in separate Tables. Adopted values for B(E3; O1+ → 31-) are presented in Table VII, together with the E3 transition strengths, in Weisskopf units, and the product Ex(31-) x B(E3; O1+ → 31--) expressed as a percentage of the energy-weighted E3 sum-rule strength. An evaluation is made of the reliability of B(E3; O1+ → 31-) values deduced from deformation parameters β3. The literature has been covered to March 1988

  17. EBIC and LBIC studies of the properties of extended defects in plastically deformed silicon

    The results of comparative experimental studies of one- and two-dimensional defects in plastically deformed silicon by the electron-beam-induced current (EBIC) and light-beam-induced current (LBIC) techniques are reported. It is shown that the contrast of two-dimensional defects (dislocation trails) in the LBIC method can by much more pronounced than that in the EBIC technique, which is in good agreement with the results of calculations. The higher sensitivity of the LBIC technique is mainly due to deeper penetration of the optical beam into the material in comparison to the penetration of the electron beam of a scanning electron microscope

  18. FlexyDos3D: a deformable anthropomorphic 3D radiation dosimeter: radiation properties

    De Deene, Yves; Skyt, Peter Sandegaard; Hill, Robin; Booth, Jeremy T

    2015-01-01

    registration software.A new three dimensional anthropomorphically shaped flexible dosimeter, further called 'FlexyDos3D', has been constructed and a new fast optical scanning method has been implemented that enables scanning of irregular shaped dosimeters. The FlexyDos3D phantom can be actuated and deformed...... during the actual treatment. FlexyDos3D offers the additional advantage that it is easy to fabricate, is non-toxic and can be molded in an arbitrary shape with high geometrical precision.The dosimeter formulation has been optimized in terms of dose sensitivity. The influence of the casting material and...

  19. Toroidal resonance: relation to pygmy mode, vortical properties and anomalous deformation splitting

    Nesterenko, V O; Repko, A; Kleinig, W; Reinhard, P -G

    2016-01-01

    We review a recent progress in investigation of the isoscalar toroidal dipole resonance (TDR). A possible relation of the TDR and low-energy dipole strength (also called a pygmy resonance) is analyzed. It is shown that the dipole strength in the pygmy region can by understood as a local manifestation of the collective vortical toroidal motion at the nuclear surface. Application of the TDR as a measure of the nuclear dipole vorticity is discussed. Finally, an anomalous splitting of the TDR in deformed nuclei is scrutinized.

  20. Grain size effects on the tensile properties and deformation mechanisms of a magnesium alloy, AZ31B, sheet

    The grain size dependence of the tensile properties and the deformation mechanisms responsible for those properties are examined for Mg alloy, AZ31B, sheet. Specifically, the Hall-Petch effect and strain anisotropy (r-value) are characterized experimentally, and interpreted using polycrystal plasticity modeling. {1 0 . 2} extension twins, {1 0 . 1} contraction twins, and so-called 'double-twins' are observed via microscopy and diffraction-based techniques, and the amount of twinning is found to increase with increasing grain size. For the sheet texture and tensile loading condition examined, {1 0 . 2} extension twinning is not expected, yet the polycrystal plasticity model predicts the observed behavior, including this 'anomalous' tensile twinning. The analysis shows that the Hall-Petch strength dependence, of the polycrystal as a whole, is primarily determined by the grain size dependence of the strength of the prismatic slip systems

  1. Theory and measurement of properties of two-phase materials in the plastic-viscous deformation range

    An extensive literature survey shows, that theoretical equations available are inadequate to predict the viscosity of suspensions without limitation of the concentration of the dispersed phase, the shape and orientation of the suspended particles. Based on physically derived and experimentally verified equations for the theoretical prediction of transport and/or field properties of solid two-phase materials with penetration structure, an attempt has been made to predict the viscosity of suspensions and the high temperature creep of two-phase solid materials with the aid of so-called structure parameters. The justification for the treatment of the problem in such a way is given by the consideration of the viscocity as a transport property and by the existing analogies between viscous and viscoplastic deformation. (orig./RW)

  2. Influence of temperature of intensive plastic deformation (at 300 and at 77 K) on return of physical-mechanical properties of zirkonium

    Influence of intensive plastic (IP) deformation of rolling on 90% at 300 and 77 K, and the subsequent isochronous annealings in an interval 373...773 K on structure and physical-mechanical properties of iodide zirconium is investigated. It is shown, that as a result of IP deformation of rolling at 300 and 77 K the density of dislocations increases from 108 cm-2 up to 1011 cm-2, nanostructure (with the size of subgrains ? 100 nm) is formed, microhardness on 80 and 125%, and resistivity on 13,5 and 25% increase according to temperatures of deformation, and dislocation peak of internal friction appears at 150 K. The stages of return are determined, and it is shown that the decreasing temperature of deformation from 300 up to 77 K reduces heat resistance of a substructure and physical-mechanical properties of zirconium.

  3. $\\beta$-decay properties for neutron-rich Kr-Tc isotopes from deformed pn-QRPA calculations with realistic forces

    Fang, Dong-Liang; Suzuki, Toshio

    2012-01-01

    In this work we studied $\\beta$-decay properties for deformed neutron-rich nuclei in the region Z=36-43. We use the deformed pn-QRPA methods with the realistic CD-Bonn forces, and include both the Gamow-Teller and first-forbidden types of decays in the calculation. The obtained $\\beta$-decay half-lives and neutron-emission probabilities of deformed isotopes are compared with experiment as well as with previous calculations. The advantages and disadvantages of the method are discussed.

  4. Experimental Study of the Bending Properties and Deformation Analysis of Web-Reinforced Composite Sandwich Floor Slabs with Four Simply Supported Edges

    Qi, Yujun; Fang, Hai; Liu, Weiqing

    2016-01-01

    Web-reinforced composite sandwich panels exhibit good mechanical properties in one-way bending, but few studies have investigated their flexural behavior and deformation calculation methods under conditions of four simply supported edges. This paper studies the bending performance of and deformation calculation methods for two-way web-reinforced composite sandwich panels with different web spacing and heights. Polyurethane foam, two-way orthogonal glass-fiber woven cloth and unsaturated resin...

  5. Effects of Coupled Structural and Diagenetic Processes on Deformation Localization and Fluid Flow Properties in Sandstone Reservoirs of the Southwestern United States

    Elliott, S. J.; Eichhubl, P.; Landry, C. J.

    2014-12-01

    Fluid flow tends to be restricted perpendicular to deformation bands through the combined effects of mechanical grain size reduction, porosity loss, and preferred cementation relative to the adjacent host rock. Deformation bands that occur in association with reservoir scale faults can impact reservoir-scale fluid flow and fault seal behavior, potentially imparting a permeability anisotropy to reservoir rocks. We use a combination of Hg-intrusion porosimetry, high-resolution 2D-image analysis of pore size distributions, and detailed compositional analyses obtained from integrating petrographic and SEM-based imaging techniques, including SEM-cathodoluminescence, backscattered electron imaging, and energy-dispersive X-ray spectroscopy, to (1) assess the effects of coupled chemical and mechanical processes leading to deformation localization within various detrital compositions [Cedar Mesa, Navajo, and Entrada sandstones] and (2) to quantify the effect of these processes on single and multiphase fluid flow as a function of host rock properties, structural position, and deformation band textural and diagenetic properties. Within each sample, bands of differing kinematic properties and structural style, i.e. shear bands, shear enhanced compaction bands etc., were identified and pre-kinematic pore-filling cements, as well as syn- and post-kinematic cements including various clay minerals, were distinguished for both the host rock and associated deformation bands. Although the deformation bands display a variety of textures and diagenetic attributes, initial petrophysical results suggest that the flow properties - permeability and capillary pressure curves - of the bands in the formations studied are very similar. However, both individual and clustered deformation bands of the Navajo Sandstone contain open or partially cemented cross-cutting fractures that could act as flow pathways across the deformation bands.

  6. Electric-dipole transitions and octupole softness in odd-A rare-earth nuclei

    It is found that B(E1) values calculated by using a model, in which one quasiparticle is coupled to a rotor, are more than an order of magnitude too small compared with measured B(E1) values in low-energy transitions observed in the yrast spectroscopy of odd-A rare-earth nuclei. Thus, the measured B(E1) values are analyzed by introducing the parameters which effectively take into account the octupole softness. An estimate of the parameters based on a microscopic model is made, and a discrepancy between the estimated values and the values necessary for reproducing data is found. (au)

  7. Progress Towards A Permanent Octupole Magnetic Ultra-Cold Neutron Trap for Lifetime Measurements

    Leung, Kent

    2008-01-01

    The current knowledge of the neutron $\\beta$-decay lifetime has come under scrutiny as of late due to large disagreements between recent precise measurements. Measurements using magnetically trapped Ultra-Cold Neutrons (UCNs) offer the possibility of storage without spurious losses which can provide a reliable value for the neutron lifetime. The progress towards realizing a neutron lifetime measurement using a Ioffe-type trap made with a Halbach-type permanent octupole magnet is presented here. The experimental procedure extracts a gas of UCNs into vacuum, which reduces many known channels of neutron losses, and detects the neutron decays via in-situ detection of the produced protons.

  8. High-power ion-cyclotron-resonance heating in the Wisconsin Levitated Octupole

    Ion cyclotron resonance heating has been investigated, both experimentally and theoretically, on the Wisconsin Levitated Octupole. Heating of both ions and electrons has been observed. Typically, a two component ion energy distribution is produced (300 eV and 50 eV) with the application of 500 kW of rf power into a 5 x 1012 cm-3 density plasma. Power is coupled to the plasma with an antenna that also serves as the inductor of an oscillator tank circuit. The oscillator is tunable from 1 to 3 MHz and can be applied for periods up to 10 msec. The experiments were performed with hydrogen, gun injected plasmas

  9. Study of microstructural evolution, microstructure-mechanical properties correlation and collaborative deformation-transformation behavior of quenching and partitioning (Q and P) steel

    Sun, Jing; Yu, Hao, E-mail: yhzhmr@126.com; Wang, Shaoyang; Fan, Yongfei

    2014-02-24

    This paper presents a detailed characterization of the microstructural evolution of quenching and partitioning (Q and P) steel by dilatometer, X-ray diffraction and scanning electron microscopy. Influence of partitioning time on mechanical properties was investigated and the relationship between microstructures and mechanical properties was established. The results indicate that bainite transformation occurs at the preliminary stage of partitioning and the amount is proportional to quenching temperature. Martensite softening, bainite transformation kinetics, amount and stability of retained austenite collaboratively have effects on mechanical properties. The purpose of the EBSD investigation is to study the changes in the microstructure of the Q and P steel during deformation and obtain a better understanding of collaborative deformation-transformation behavior. During deformation, plastic deformation preferentially occurred in the vicinity of ferritemartensite interfaces and spread to the interior of ferrite grain with strain increasing. Plastic deformation started to occur in martensite after large strain. Furthermore, grain rotation occurred in some austenite grains or divided into subgrains during deformation.

  10. Geometrical and mechanical properties of the fractures and brittle deformation zones based on the ONKALO tunnel mapping, 2400 - 4390 m tunnel chainage

    Moenkkoenen, H.; Rantanen, T.; Kuula, H. [WSP Finland Oy, Helsinki (Finland)

    2012-05-15

    In this report, the rock mechanics parameters of fractures and brittle deformation zones have been estimated in the vicinity of the ONKALO area at the Olkiluoto site, western Finland. This report is an extension of the previously published report: Geometrical and Mechanical properties if the fractures and brittle deformation zones based on ONKALO tunnel mapping, 0-2400 m tunnel chainage (Kuula 2010). In this updated report, mapping data are from 2400-4390 m tunnel chainage. Defined rock mechanics parameters of the fractures are associated with the rock engineering classification quality index, Q', which incorporates the RQD, Jn, Jr and Ja values. The friction angle of the fracture surfaces is estimated from the Jr and Ja numbers. There are no new data from laboratory joint shear and normal tests. The fracture wall compressive strength (JCS) data are available from the chainage range 1280-2400 m. Estimation of the mechanics properties of the 24 brittle deformation zones (BDZ) is based on the mapped Q' value, which is transformed to the GSI value in order to estimate strength and deformability properties. A component of the mapped Q' values is from the ONKALO and another component is from the drill cores. In this study, 24 BDZs have been parameterized. The location and size of the brittle deformation are based on the latest interpretation. New data for intact rock strength of the brittle deformation zones are not available. (orig.)

  11. Role of deformation on giant resonances within the QRPA approach and the Gogny force

    Peru, S

    2008-01-01

    Fully consistent axially-symmetric-deformed Quasi-particle Random Phase Approximation (QRPA) calculations have been performed, in which the same Gogny D1S effective force has been used for both the Hartree-Fock-Bogolyubov mean field and the QRPA approaches. Giant resonances calculated in deformed $^{26-28}$Si and $^{22-24}$Mg nuclei as well as in the spherical $^{30}$Si and $^{28}$Mg isotopes are presented. Theoretical results for isovector-dipole and isoscalar monopole, quadrupole, and octupole responses are presented and the impact of the intrinsic nuclear deformation is discussed.

  12. Investigation of mechanical properties and operative deformation mechanism in nano-crystalline Ni-Co/SiC electrodeposits

    Lari Baghal, S.M. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Amadeh, A., E-mail: amadeh@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Heydarzadeh Sohi, M. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of)

    2012-04-30

    Highlights: Black-Right-Pointing-Pointer The tensile properties of Ni-Co and Ni-Co/SiC deposits were investigated. Black-Right-Pointing-Pointer The SiC particles enhanced tensile strength and ductility of nano-structured composites. Black-Right-Pointing-Pointer The deformation mechanism at low and high strain rates were studied. - Abstract: Ni-Co/SiC nano-composites were prepared via electrodeposition from a modified Watts bath containing SiC particles with average particle size of 50 nm, SDS as surfactant and saccharin as grain refiner in appropriate amounts. The effect of nano-particle incorporation on microstructure, mechanical properties and deformation mechanism of electrodeposits were investigated. The mechanical properties of electrodeposits were investigated by Vickers microhardness and tensile tests. The results indicated that incorporation of SiC particles into a 15 nm Ni-Co matrix had no considerable effect on its microhardness and yield strength, that is, dispersion hardening did not operate in this range of grain size. However it was observed that co-deposition of uniform distributed SiC particles can significantly improve the ultimate tensile strength and elongation to failure of the deposits. Calculation of apparent activation volume from tensile test results at different strain rates proved that incorporation of SiC nano-particles are responsible for stress-assisted activation of GB atoms mechanism that can significantly increase the plasticity. Nano-crystalline Ni-Co matrix showed a mixed mod behavior of ductile and brittle fracture whereas incorporation of SiC particles and increasing the strain rate promoted ductile fracture mode.

  13. The effect of post-deformation aging on superelastic properties of Ni{sub 50.9}Ti thin wires attaining micro and nano-substructure

    Abbasi-Chianeh, V., E-mail: vahid61abbasi@gmail.com [Faculty of Mechanics Engineering, Urmia University of Technology, Urmia (Iran, Islamic Republic of); Research Center for Advanced Materials and Mineral Processing, Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Khalil-Allafi, J.; Kazemi-choobi, K. [Research Center for Advanced Materials and Mineral Processing, Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of)

    2013-06-25

    Highlights: ► Precipitation of Ni{sub 4}Ti{sub 3} during aging at 450 °C is hindered after severe cold work. ► Nanostructure formation improves the superelastic behavior of Ni-rich NiTi. ► Deformations less than 0.4 result in work hardening and reduce plateau strain. ► Deformations more than 0.4 yield in high stress and strain values of upper plateau. -- Abstract: Superelastic properties of Ni{sub 50.9}Ti shape memory wires were studied after cold drawing and post-deformation annealing at 450 °C. Characteristic transformation temperatures were determined using differential scanning calorimetry. Microstructural investigations were performed using optical and transmission electron microscopy. Results indicate that deformations more than 0.4 of true strain yield in high stress and high strain values of upper plateau. On the other hand, deformations less than 0.4 result in work hardening and reduce plateau strain. Post-deformation heat treatment at 450 °C leads to precipitation of Ni{sub 4}Ti{sub 3} particles and development of recovered microstructure in slightly cold drawn wires. Post-deformation annealing of wires with cold work value of 0.6 in true strain develop nanocrystalline microstructure and hindered the formation of Ni{sub 4}Ti{sub 3} precipitates. Precipitation of Ni{sub 4}Ti{sub 3} particles improves the superelastic properties of not cold drawn wires. However, in comparison with annealed and aged wires, severely deformed wires attain better superelastic properties after annealing at 450 °C without any Ni{sub 4}Ti{sub 3} precipitates.

  14. The effect of post-deformation aging on superelastic properties of Ni50.9Ti thin wires attaining micro and nano-substructure

    Highlights: ► Precipitation of Ni4Ti3 during aging at 450 °C is hindered after severe cold work. ► Nanostructure formation improves the superelastic behavior of Ni-rich NiTi. ► Deformations less than 0.4 result in work hardening and reduce plateau strain. ► Deformations more than 0.4 yield in high stress and strain values of upper plateau. -- Abstract: Superelastic properties of Ni50.9Ti shape memory wires were studied after cold drawing and post-deformation annealing at 450 °C. Characteristic transformation temperatures were determined using differential scanning calorimetry. Microstructural investigations were performed using optical and transmission electron microscopy. Results indicate that deformations more than 0.4 of true strain yield in high stress and high strain values of upper plateau. On the other hand, deformations less than 0.4 result in work hardening and reduce plateau strain. Post-deformation heat treatment at 450 °C leads to precipitation of Ni4Ti3 particles and development of recovered microstructure in slightly cold drawn wires. Post-deformation annealing of wires with cold work value of 0.6 in true strain develop nanocrystalline microstructure and hindered the formation of Ni4Ti3 precipitates. Precipitation of Ni4Ti3 particles improves the superelastic properties of not cold drawn wires. However, in comparison with annealed and aged wires, severely deformed wires attain better superelastic properties after annealing at 450 °C without any Ni4Ti3 precipitates

  15. Elastic Deformation Properties of Implanted Endobronchial Wire Stents in Benign and Malignant Bronchial Disease: A Radiographic In Vivo Evaluation

    Purpose: To evaluate the long-term mechanical behavior in vivo of expandable endobronchial wire stents, we imaged three different prostheses in the treatment of tracheobronchial disease. Methods: Six patients with bronchial stenoses (three benign, three malignant) underwent insertion of metallic stents. Two self-expandable Wallstents, two balloon-expandable tantalum Strecker stents and two self-expandable nitinol Accuflex stents were used. Measurements of deformation properties were performed during voluntary cough by means of fluoroscopy, at 1 month and 7-10 months after implantation. The procedures were videotaped, their images digitized and the narrowing of stent diameters calculated at intervals of 20 msec. Results: After stent implantation all patients improved with respect to ventilatory function. Radial stent narrowing during cough reached 53% (Wallstent), 59% (tantalum Strecker stent), and 52% (nitinol Accuflex stent) of the relaxed post-implantation diameter. Stent compression was more marked in benign compared with malignant stenoses. In the long term permanent deformation occurred with the tantalum Strecker stents; the other stents were unchanged. Conclusion: Endobronchial wire stents can be helpful in the treatment of major airway collapse and obstructing bronchial lesions. However, evidence of material fatigue as a possible effect of exposure to recurrent mechanical stress on the flexible mesh tube may limit their long-term use. This seems to be predominantly important in benign bronchial collapse

  16. Multipole modes in deformed nuclei within the finite amplitude method

    Kortelainen, M; Nazarewicz, W

    2015-01-01

    Background: To access selected excited states of nuclei, within the framework of nuclear density functional theory, the quasiparticle random phase approximation (QRPA) is commonly used. Purpose: We present a computationally efficient, fully self-consistent framework to compute the QRPA transition strength function of an arbitrary multipole operator in axially-deformed superfluid nuclei. Methods: The method is based on the finite amplitude method (FAM) QRPA, allowing fast iterative solution of QRPA equations. A numerical implementation of the FAM-QRPA solver module has been carried out for deformed nuclei. Results: The practical feasibility of the deformed FAM module has been demonstrated. In particular, we calculate the quadrupole and octupole strength in a heavy deformed nucleus $^{240}$Pu, without any truncations in the quasiparticle space. To demonstrate the capability to calculate individual QRPA modes, we also compute low-lying negative-parity collective states in $^{154}$Sm. Conclusions: The new FAM imp...

  17. Deformation Properties of Tailor Welded Blank Made of Dual Phase Steels

    Schrek Alexander; Švec Pavol; Gajdošová Veronika

    2016-01-01

    The paper is dedicated to forming and properties of passenger car’s B-pillar reinforcement drawn from simple blank and alternatively tailor-welded blank (TWB). Drawn part is characterised by a place with a large strain, while forming process simulation did not confirm the creation of crack using the TWB consisting of dual phase HCT980X instead of previous HCT600 steel. It is because HCT980X steel has higher strength and lower ductile properties. The analysis of properties of drawn parts is fo...

  18. Construction and Operational Experience with a Superconducting Octupole Used to Trap Antihydrogen

    Wanderer P.; Escallier, J.; Marone, A.; Parker, B.

    2011-09-06

    A superconducting octupole magnet has seen extensive service as part of the ALPHA experiment at CERN. ALPHA has trapped antihydrogen, a crucial step towards performing precision measurements of anti-atoms. The octupole was made at the Direct Wind facility by the Superconducting Magnet Division at Brookhaven National Laboratory. The magnet was wound with a six-around-one NbTi cable about 1 mm in diameter. It is about 300 mm long, with a radius of 25 mm and a peak field at the conductor of 4.04 T. Specific features of the magnet, including a minimal amount of material in the coil and coil ends with low multipole content, were advantageous to its use in ALPHA. The magnet was operated for six months a year for five years. During this time it underwent about 900 thermal cycles (between 4K and 100K). A novel operational feature is that during the course of data-taking the magnet was repeatedly shut off from its 950 A operating current. The magnet quenches during the shutoff, with a decay constant of 9 ms. Over the course of the five years, the magnet was deliberately quenched many thousands of times. It still performs well.

  19. Design of a collision cell coupled to an octupole in order to study ionic complexes

    The study of chemical reactivity within mixed ionic metal-water complexes, e.g.M(H2O)n+ with 1 2O)n+ complexes, we have developed a collision cell coupled to an octupole. The development of this chamber was realized on the base of ions trajectories numerical simulations. Collision cell parameters are defined in agreement with collisional dynamics laws and allow measurements of accurate reaction cross sections. In particular, the octupole, directly placed inside the collision chamber, traps in-coming complex ions as well as ionic products of the collisions along the propagation axis z, and collects them for further analysis. The cell contains a specific adjustment tool that slows down in-coming ionic complexes before collision. The system is efficient along the z axis for a kinetic energy range of in-coming complexes between 10 and 520 eV in the laboratory referential. This device will be used to study the behaviour of metallic ions in solution and will have applications in fields like reprocessing and nuclear wastes storage. (author)

  20. Effect of heat treatment and deformation on the microstructure and mechanical properties of SP-700 titanium alloy

    Nieh, Jo-Kuang; Pan, Kuen-Sung [National Central University, Taoyuan, Taiwan (China). Dept. of Mechanical Engineering; Lee, Sheng-Long [National Central University, Taoyuan, Taiwan (China). Dept. of Mechanical Engineering; National Central University, Taoyuan, Taiwan (China). Inst. of Materials Science and Engineering

    2015-12-15

    This study investigates the effects of cold working prior to aging on the microstructure and mechanical properties of SP-700 titanium alloy. The results indicate that the microstructure of the quenched alloy comprises blocky primary α, retained β, and acicular α'' martensite distributed in the β matrix. The retained β is transformed to denser and finer brittle acicular martensite α'' by stress-induced martensitic transformation and the quantity of retained β decreases with higher degrees of cold working. The quenched alloy exhibits not only low yield strength, but the stress-induced martensite leads to a distinct increase in strength with good ductility. Plastic deformation prior to the aging treatment produces a great increase in the yield strength due to refinement of the precipitate microstructure, leading to the ratio of strength increment and ductility being very low.

  1. Effect of heat treatment and deformation on the microstructure and mechanical properties of SP-700 titanium alloy

    This study investigates the effects of cold working prior to aging on the microstructure and mechanical properties of SP-700 titanium alloy. The results indicate that the microstructure of the quenched alloy comprises blocky primary α, retained β, and acicular α'' martensite distributed in the β matrix. The retained β is transformed to denser and finer brittle acicular martensite α'' by stress-induced martensitic transformation and the quantity of retained β decreases with higher degrees of cold working. The quenched alloy exhibits not only low yield strength, but the stress-induced martensite leads to a distinct increase in strength with good ductility. Plastic deformation prior to the aging treatment produces a great increase in the yield strength due to refinement of the precipitate microstructure, leading to the ratio of strength increment and ductility being very low.

  2. Effect of the Spinning Deformation Processing on Mechanical Properties of Al-7Si-0.3Mg Alloys

    Cheng, Yin-Chun; Lin, Chih-Kuang; Tan, An-Hung; Hsu, Shih-Yuan; Lee, Sheng-Long

    2012-09-01

    This study investigates the mechanical properties of Al-7Si-0.3Mg (A356) alloy affected by the spinning deformation processing (SDP). The cast structure of the A356 alloy becomes elongated with increasing reduction in thickness. This leads to reduction of casting defects, and refines and distributes the eutectic silicon phase throughout the Al-matrix. The hardness tends to reach a steady value due to the uniformity of the microstructure with the reduction in thickness. The SDP leads to a re-arrangement in the eutectic region, which forces the propagation of cracks through the ductile ?-Al phase. The tensile strength and elongation increases accordingly. The improvement on tensile strength and elongation produces the best quality index for A356 alloy.

  3. Creep Properties and Deformation Mechanisms of a FGH95 Ni-based Superalloy

    Xie, Jun; Tian, Su-gui; Zhou, Xiao-ming

    2013-07-01

    By means of full heat treatment, microstructure observation, lattice parameters determination, and the measurement of creep curves, an investigation has been conducted into the microstructure and creep mechanisms of FGH95 Ni-based superalloy. Results show that after the alloy is hot isostatically pressed, coarse ?' phase discontinuously distributes along the previous particle boundaries. After solution treatment at high temperature and aging, the grain size has no obvious change, and the amount of coarse ?' phase decreases, and a high volume fraction of fine ?' phase dispersedly precipitates in the ? matrix. Moreover, the granular carbides are found to be precipitated along grain boundaries, which can hinder the grain boundaries' sliding and enhance the creep resistance of the alloy. By x-ray diffraction analysis, it is indicated that the lattice misfit between the ? and ?' phases decreases in the alloy after full heat treatment. In the ranges of experimental temperatures and applied stresses, the creep activation energy of the alloy is measured to be 630.4 kJ/mol. During creep, the deformation mechanisms of the alloy are that dislocations slip in the ? matrix or shear into the ?' phase. Thereinto, the creep dislocations move over the ?' phase by the Orowan mechanism, and the < { 1 10 } rangle super-dislocation shearing into the ?' phase can be decomposed to form the configuration of (1/3) < { 1 12 } rangle super-Shockleys' partials and the stacking fault.

  4. Effect of hydrogen on the low-temperature deformation properties of neutron-irradiated vanadium

    The influence of hydrogen on the low temperature deformation characteristics of neutron-irradiated vanadium single crystals has been investigated in compression in the temperature range from 77 to 5500K. The addition of hydrogen to neutron-irradiated vanadium causes a local perturbation in the temperature dependence of yield stress that is similar to unirradiated vanadium. A mechanism based on the stress induced reorientation of small hydrides by the stress fields of moving dislocations has been put forward to account for this observation. In contrast, the presence of hydrogen prior to irradiation results only in a general rise in the yield stress. The disappearance of the local perturbation is attributed to the trapping of hydrogen atoms to form stable complexes during irradiation, thereby eliminating the phenomenon of stress-induced reorientation of hydrides. The fact that the hydrogen does not reduce the thermal component of the yield stress implies that the cancellation of neutron-produced defects by hydrogen is unlikely. The effect of prestraining prior to neutron irradiation resulted in a reduction of the increase in the yield stress due to the neutron irradiation. This reduction is probably due to the fact that the additional dislocations provide an increased sink density

  5. The influence of elastic deformation on the properties of the magnetoacoustic emission (MAE) signal for GO electrical steel

    Piotrowski, Leszek, E-mail: lesio@mif.pg.gda.pl [Gdansk University of Technology, Gdansk 80-233 (Poland); Chmielewski, Marek; Augustyniak, Boleslaw [Gdansk University of Technology, Gdansk 80-233 (Poland)

    2012-08-15

    Magnetic properties of the grain oriented (GO) electrical steels are strongly affected by the stresses, both external and internal. The change is important even for the deformation resulting in stress level much lower than their yield limits. In this paper we present the results of investigation of the influence of compression and tension on the magnetoacoustic emission (MAE) signal properties. The experiment was performed with the help of bending machine in which the samples (0.3 mm thick, M140-30 S GO electrical steel) glued to the non-magnetic (austenitic steel) 8 mm thick bars were bent. The samples cut out in two directions (parallel and perpendicular to the rolling direction) were investigated. The elongation was measured directly with the help of tensometric bridge. Various parameters of the MAE signal, such as e.g. signal intensity and MAE peaks separation, have been examined. - Highlights: Black-Right-Pointing-Pointer Magnetic properties of the GO electrical steels are strongly affected by stress. Black-Right-Pointing-Pointer The non-destructive method of investigation of the ready-made components is needed. Black-Right-Pointing-Pointer Magnetoacoustic emission is sensitive to stress-induced domain structure changes. Black-Right-Pointing-Pointer Advanced signal analysis allows to determine the stress level in an unambiguous way.

  6. The influence of elastic deformation on the properties of the magnetoacoustic emission (MAE) signal for GO electrical steel

    Magnetic properties of the grain oriented (GO) electrical steels are strongly affected by the stresses, both external and internal. The change is important even for the deformation resulting in stress level much lower than their yield limits. In this paper we present the results of investigation of the influence of compression and tension on the magnetoacoustic emission (MAE) signal properties. The experiment was performed with the help of bending machine in which the samples (0.3 mm thick, M140-30 S GO electrical steel) glued to the non-magnetic (austenitic steel) 8 mm thick bars were bent. The samples cut out in two directions (parallel and perpendicular to the rolling direction) were investigated. The elongation was measured directly with the help of tensometric bridge. Various parameters of the MAE signal, such as e.g. signal intensity and MAE peaks separation, have been examined. - Highlights: ► Magnetic properties of the GO electrical steels are strongly affected by stress. ► The non-destructive method of investigation of the ready-made components is needed. ► Magnetoacoustic emission is sensitive to stress-induced domain structure changes. ► Advanced signal analysis allows to determine the stress level in an unambiguous way.

  7. Deformation Properties of Tailor Welded Blank Made of Dual Phase Steels

    Schrek Alexander

    2016-03-01

    Full Text Available The paper is dedicated to forming and properties of passenger car’s B-pillar reinforcement drawn from simple blank and alternatively tailor-welded blank (TWB. Drawn part is characterised by a place with a large strain, while forming process simulation did not confirm the creation of crack using the TWB consisting of dual phase HCT980X instead of previous HCT600 steel. It is because HCT980X steel has higher strength and lower ductile properties. The analysis of properties of drawn parts is focused on the simulated crash test in Dynaform software. Obtained sizes of drawn forces in simulated frame of the drawn parts and their comparison proved the possibility of the replacement the 1.2 mm thick simple blank from HCT600 steel with the 1 mm thick TWB consisting of HCT600 and HCT980X steel. The changed thickness of the simple blank caused 20% weight saving while containing the same properties of the drawn part.

  8. Control of electric and dielectric properties of conductive polymer composites by compression deformation

    Pelíšková, M.; Vilčáková, J.; Moučka, R.; Sáha, P.; Quadrat, Otakar; Stejskal, Jaroslav; Omastová, M.

    Budapest : Budapest University of Technology and Economics, 2007. s. 89-89. [Functional Fillers for Advanced Applications EUROFILLERS. 26.08.2007-30.08.2007, Zalakaros] Institutional research plan: CEZ:AV0Z40500505 Keywords : conductive polymers * electric and dielectric properties Subject RIV: CD - Macromolecular Chemistry

  9. Properties enhancement and recoil loop characteristics for hot deformed nanocrystalline NdFeB permanent magnets

    Nanocrystalline NdFeB magnets were prepared by spark plasma sintering (SPS) and SPS followed by HD using melt spun ribbons as the starting materials. The microstructure of SPSed and HDed magnets were analyzed. The effects of process including temperature and compression ratio on the microstructure and properties were investigated. High magnetic properties were obtained in anisotropic HDed magnets. The combination of Zn and Dy additions was successfully employed to improve the coercivity and thermal stability of the SPSed magnets. Open recoil loops were found in these magnets with Nd-rich composition and without soft magnetic phase for the first time. The relationship between the recoil loops and microstructure for SPS and HD NdFeB magnets were investigated. The investigations showed that the magnetic properties of SPS+HDed magnets are related to the extent of the aggregation of Nd-rich phase, which was formed during HD due to existence of porosity in SPSed precursor. Large local demagnetization fields induced by the Nd-rich phase aggregation leads to the open loops and significantly reduced the coercivity. By reducing the recoil loop openness, the magnetic properties of HDed NdFeB magnets were successfully improved. (author)

  10. Mechanical properties and deformation behavior of as-cast Ti-Sn alloys

    In this study, the mechanical properties of as-cast Ti-Sn alloys with Sn content ranging from 1 to 30 wt.% prepared using a dental cast machine were investigated and compared with commercially pure titanium (c.p. Ti), which was used as a control. Experimental results indicated that the diffraction peaks of all the Ti-Sn alloys matched those for α Ti, and no β phase peaks or any intermediate phases were found. All the Ti-Sn alloys had higher bending strengths, bending moduli and elastic recovery angles than those of c.p. Ti. For example, the bending strength of the Ti-1Sn alloy was higher than that of c.p. Ti by 68%, its bending modulus was higher than that of c.p. Ti by 43% and its elastically recoverable angle was higher than that of c.p. Ti by as much as 240%. Additionally, the Ti-1Sn, Ti-5Sn and Ti-10Sn alloys exhibited ductile properties. When the Sn content was 20 wt.% or greater, the alloys showed brittle properties. Our research suggested that Ti-1Sn alloy had the most favorable mechanical properties of all the metals in this study, making it the best candidate for prosthetic dental applications.

  11. The mechanical properties, deformation and thermomechanical properties of alkali treated and untreated Agave continuous fibre reinforced epoxy composites

    Research highlights: ? New renewable and biodegradable Agave americana fibre. ? Environmentally free materials. ? Good mechanical properties of Agave fibre reinforced epoxy composite materials. ? Surface modification of the fibre (Alkali treatment) imported good mechanical properties. ? Future scope in light weight materials manufacture. -- Abstract: The mechanical properties such as tensile, compressive, flexural, impact strength and water absorption of the alkali treated continuous Agave fibre reinforced epoxy composite (TCEC) and untreated continuous Agave fibre reinforced epoxy composite (UTCEC) were analysed. A comparison of the surfaces of TCEC and UTCEC composites was carried out by dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermomechanical properties of the composite reinforced with sodium hydroxide (NaOH) treated Agave fibres were considerably good as the shrinkage of the fibre during alkali treatment had facilitated more points of fibre resin interface. The SEM micrograph and FTIR spectra of the impact fracture surfaces of TCEC clearly demonstrate the better interfacial adhesion between fibre and the matrix. In both analyses the TCEC gave good performance than UTCEC and, thus, there is a scope for its application in light weight manufacture in future.

  12. Octupole correlations in neutron-rich {sup 143,145}Ba and a type of superdeformed band in {sup 145}Ba

    Zhu, S.J.; Wang, M.G.; Long, G.L.; Zhu, L.Y.; Gan, C.Y.; Yang, L.M.; Sakhaee, M.; Li, M.; Deng, J.K. [Physics Department, Tsinghua University, Beijing 100084, Peoples Republic of (China); Zhu, S.J.; Hamilton, J.H.; Ramayya, A.V.; Jones, E.F.; Hwang, J.K.; Zhang, X.Q.; Gore, P.M.; Peker, L.K.; Drafta, G.; Babu, B.R.; Deng, J.K.; Ginter, T.N.; Beyer, C.J.; Kormicki, J.; Ter-Akopian, G.M.; Daniel, A.V. [Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States); Zhu, S.J.; Ter-Akopian, G.M.; Daniel, A.V. [Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee 37831 (United States); Ma, W.C. [Physics Department, Mississippi State University, Mississippi 39762 (United States); Cole, J.D.; Aryaeinejad, R.; Drigert, M.W. [Idaho National Engineering Laboratory, Idaho Falls, Idaho 83415 (United States); Rasmussen, J.O.; Asztalos, S.; Lee, I.Y.; Macchiavelli, A.O.; Chu, S.Y.; Gregorich, K.E.; Mohar, M.F. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ter-Akopian, G.M.; Daniel, A.V.; Oganessian, Y.T.; Kliman, J. [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna (Russia); Donangelo, R. [Universidade Federal do Rio de Janeiro, Caixa Postal 68528, RG (Brazil); Stoyer, M.A.; Lougheed, R.W.; Moody, K.J.; Wild, J.F. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Prussin, S.G. [Nuclear Engineering Department, University of California at Berkeley, Berkeley, California 94720 (United States); Kliman, J. [Institute of Physics, SASc, Dubravskacesta 9, 84228 Bratislava (Slovakia); Griffin, H.C. [University of Michigan, Ann Arbor, Michigan 48104 (United States)

    1999-11-01

    High spin states in neutron-rich odd-{ital Z} {sup 143,145}Ba nuclei have been investigated from the study of prompt {gamma} rays in the spontaneous fission of {sup 252}Cf by using {gamma}-{gamma}- and {gamma}-{gamma}-{gamma}- coincidence techniques. Alternating parity bands are identified for the first time in {sup 145}Ba and extended in {sup 143}Ba. A new side band, with equal, constant dynamic, and kinetic moments of inertia equal to the rigid body value, as found in superdeformed bands, is discovered in {sup 145}Ba. Enhanced E1 transitions between the negative- and positive-parity bands in these nuclei give evidence for strong octupole deformation in {sup 143}Ba and in {sup 145}Ba. These collective bands show competition and coexistence between symmetric and asymmetric shapes in {sup 145}Ba. Evidence is found for crossing M1 and E1 transitions between the s=+i and s={minus}i doublets in {sup 143}Ba. {copyright} {ital 1999} {ital The American Physical Society}

  13. Physical properties of hydrated tissue determined by surface interferometry of laser-induced thermoelastic deformation

    Knee meniscus is a hydrated tissue; it is a fibrocartilage of the knee joint composed primarily of water. We present results of interferometric surface monitoring by which we measure physical properties of human knee meniscal cartilage. The physical response of biological tissue to a short laser pulse is primarily thermomechanical. When the pulse is shorter than characteristic times (thermal diffusion time and acoustic relaxation time) stresses build and propagate as acoustic waves in the tissue. The tissue responds to the laser-induced stress by thermoelastic expansion. Solving the thermoelastic wave equation numerically predicts the correct laser-induced expansion. By comparing theory with experimental data, we can obtain the longitudinal speed of sound, the effective optical penetration depth and the Grueneisen coefficient. This study yields information about the laser-tissue interaction and determines properties of the meniscus samples that could be used as diagnostic parameters. (author)

  14. Mechanical properties of severely deformed ZA-27 alloy using equal channel angular extrusion

    Purcek, G.; Altan, B.S.; Miskioglu, I.; Patil, A.

    2005-09-15

    As cast ZA-27 alloy was subjected to equal channel angular extrusion (ECAE) with up to four passes using three different processing routes, and its mechanical properties (strength, hardness, ductility and extrusion load) were evaluated. The changes in the microstructure were also investigated. The ECAE was found to be quite effective in enhancing the mechanical properties of ZA-27 alloy. The strength and hardness of the alloys increased after the first ECAE pass followed by a gradual decrease with further passes for all processing routes. The elongation to failure, however, exceptionally increased with increase in the number of passes for all processing routes. Combined high strength and good ductility were obtained in the alloy after the first pass. The strength and maximum extrusion load showed similar trends with the number of passes for all processing routes. (author)

  15. On the relationship between large-deformation properties of wheat flour dough and baking quality

    Sliwinski, E.L.; Kolster, P.; Vliet, T., van

    2004-01-01

    Baking performance for bread and puff pastry was tested for Six European and two Canadian wheat cultivars and related to the rheological and fracture properties in uniaxial extension of optimally mixed flour-water doughs and doughs to which a mix of bakery additives was added. Extensive baking tests were performed as a function of water addition for puff pastry and as a function of water addition and mixing time for bread. For optimum baking performance, puff pastry doughs required lower wate...

  16. Influence of substructure on mechanical properties of austenitic alloys deformed by warm rolling

    A connection between a substructure and mechanical properties of some iron base austenitic alloys, differing in carbon, and carbide-forming element contents and in stacking fault energies after warm rolling, is studied. It is shown that the maximum value of yield strength after cold hardening is achieved in the alloy with low stacking fault energy due to the formation of high density of thin twins

  17. Influence of substructure on mechanical properties of austenitic alloys deformed by warm rolling

    Izotov, V.I.; Virakhovskij, Yu.G.; Marusenko, S.Ya. (Tsentral' nyj Nauchno-Issledovatel' skij Inst. Chernoj Metallurgii, Moscow (USSR). Inst. Metallovedeniya i Fiziki Metallov)

    1983-08-01

    A connection between a substructure and mechanical properties of some iron base austenitic alloys, differing in carbon, and carbide-forming element contents and in stacking fault energies after warm rolling, is studied. It is shown that the maximum value of yield strength after cold hardening is achieved in the alloy with low stacking fault energy due to the formation of high density of thin twins.

  18. Annealing behaviour and mechanical properties of severely deformed interstitial free steel

    Highlights: ► Microstructure and micro-texture evolution indicates continuous recrystallisation. ► HAGBs decrease from ∼80 to ∼40% due to texture clustering and orientation pinning. ► Characterisation of correlation between tensile and shear punch tests. ► Tensile behaviour evolves from stress drop to continuous yielding a work hardening. - Abstract: The evolution of microstructure, micro-texture and mechanical properties during isothermal annealing of an ultrafine grained interstitial free (IF) steel processed by Equal Channel Angular Pressing (ECAP) followed by 95% cold rolling (CR) was studied. Microstructure and micro-texture changes were characterised by Electron Back-Scattering Diffraction while mechanical properties were assessed by shear punch and uniaxial tensile testing. During annealing, homogeneous coarsening via continuous recrystallisation is accompanied by the retention of a sharp α-fibre rolling texture and a decrease in area fraction of high angle grain boundaries from ∼80% to ∼40% due to texture clustering and orientation pinning. Failure during uniaxial tension occurred without post-necking elongation after CR. Upon annealing, an evolution from stress-drop soon after yielding to a return to continuous yielding and increased work hardening was observed. Good agreement is found between experimental and estimated strengths and total elongations derived from SPT and tensile data. Tensile characteristics and mechanical properties depend on both, grain size and area fraction of HAGBs.

  19. Carbon deposition during brittle rock deformation: Changes in electrical properties of fault zones and potential geoelectric phenomena during earthquakes

    Mathez, E A; Roberts, J J; Duba, A G; Kronenberg, A K; Karner, S L

    2008-05-16

    To investigate potential mechanisms for geoelectric phenomena accompanying earthquakes, we have deformed hollow cylinders of Sioux quartzite to failure in the presence of carbonaceous pore fluids and investigated the resulting changes in electrical conductivity and carbon distribution. Samples were loaded at room temperature or 400 C by a hydrostatic pressure at their outer diameter, increasing pressure at a constant rate to {approx}290 MPa. Pore fluids consisted of pure CO, CO{sub 2}, CH{sub 4} and a 1:1 mixture of CO{sub 2} and CH{sub 4}, each with pore pressures of 2.0 to 4.1 MPa. Failure occurred by the formation of mode II shear fractures transecting the hollow cylinder walls. Radial resistivities of the cylinders fell to 2.9 to 3.1 M{Omega}-m for CO tests and 15.2 to 16.5 M{Omega}-m for CO{sub 2}:CH{sub 4} tests, compared with >23 M{Omega}-m for dry, undeformed cylinders. Carbonaceous fluids had no discernable influence on rock strength. Based on mapping using electron microprobe techniques, carbon occurs preferentially as quasi-continuous films on newly-formed fracture surfaces, but these films are absent from pre-existing surfaces in those same experiments. The observations support the hypothesis that electrical conductivity of rocks is enhanced by the deposition of carbon on fracture surfaces and imply that electrical properties may change in direct response to brittle deformation. They also suggest that the carbon films formed nearly instantaneously as the cracks formed. Carbon film deposition may accompany the development of microfracture arrays prior to and during fault rupture and thus may be capable of explaining precursory and coseismic geoelectric phenomena.

  20. Contribution to the study of mechanical properties of nuclear fuel: atomistic modelling of the deformation of uranium dioxide

    Mechanical properties of nuclear fuel are a complex problem, involving many coupled mechanisms occurring at different length scales. We used Molecular Dynamics models to bring some light on some of these mechanisms at the atomic scale. We devised a procedure to calculate transition pathways between some UO2 polymorphs, and then carried out dynamics simulations of these transitions. We confirmed the stability of the cotunnite structure at high pressure using various empirical potentials, the fluorite structure being the most stable at room pressure. Moreover, we showed a reconstructive phase transition between the fluorite and cotunnite structures. We also showed the importance of the major deformation axis on the kind of transition that occur under tensile conditions. Depending on the loading direction, a scrutinyite or rutile phase can appear. We then calculated the elastic behaviour of UO2 using different potentials. The relative agreement between them was used to produce a set of parameters to be used as input in mesoscale models. We also simulated crack propagation in UO2 single crystals. These simulations showed secondary phases nucleation at crack tips, and hinted at the importance thereof on crack propagation at higher length-scales. We then described some properties of edge dislocations in UO2. The core structures were compared for various glide planes. The critical resolved shear stress was calculated for temperatures up to 2000 K. These calculations showed a link between lattice disorder at the dislocations core and the dislocations mobility. (author)

  1. Microstructure and mechanical properties of an Al–Mg–Si tube processed by severe plastic deformation and subsequent annealing

    This study is aimed to realize evolution of microstructure and mechanical properties of aluminum 6061 alloy tube subjected to Severe Plastic Deformation (SPD) and subsequent annealing. For this purpose, the tube is initially processed by different passes of an SPD process called Tube Channel Pressing (TCP) and then subjected to a subsequent annealing at 473 °K for 2 h. Afterwards, tension test is used for the evaluation of mechanical properties while Electron Back-Scattered Diffraction (EBSD) equipped Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) are utilized for the microstructural characterizations. Results show that the Continuous Static Recrystallization (CSRX) is the main restoration phenomenon during annealing of aluminum 6061 alloy, even after imposing a moderate plastic strain. For instance, CSRX has been observed during annealing treatment after imposing an equivalent plastic strain as low as 1. However, the used annealing treatment causes different microstructural variations in specimens depending on the pass number of TCP. As an illustration, while the average grain size impressively decreases due to annealing of 1 pass TCPed specimen, it moderately increases after annealing of 5 passes TCPed specimen. This is due to development of a bimodal microstructure after 5 pass of TCP which leads to a different evolution of microstructure during successive annealing. It is also notable that TCPed and annealed specimens show higher strength and ductility compared with as TCPed specimens which is attributed to the occurrence of precipitation hardening besides restoration phenomenon during the annealing treatment

  2. Global and local deformation behavior and mechanical properties of individual phases in a quenched and partitioned steel

    Third generation advanced high strength steels produced via quenching and partitioning (Q&P) treatment are receiving increased attention. A 0.25C–3Mn–1.5Si–0.023 Al steel was subjected to Q&P processing (with varying partitioning temperature and time) resulting in the formation of complex multi-phase microstructures. The effect of Q&P parameters on the microstructure and morphology of microconstituents was analyzed. Mechanical properties of the material and of its individual microconstituents were studied via tensile testing and nanoindentation on individual microconstituents, which were identified a priori by electron back-scattered diffraction analysis. Special attention is paid to the effect of the morphology of retained austenite on its transformation stability. In situ tensile tests and digital image correlation analysis were performed to study deformation behavior of the Q&P processed steel at the micro-scale with respect to the local microstructure. The effect of local microstructure and properties of individual phases on the degree of strain partitioning is discussed

  3. Global and local deformation behavior and mechanical properties of individual phases in a quenched and partitioned steel

    Diego-Calderón, I. de, E-mail: irenedediego.calderon@imdea.org [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain); De Knijf, D. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Monclús, M.A.; Molina-Aldareguia, J.M.; Sabirov, I. [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain); Föjer, C. [ArcelorMittal Global R& D Gent, Pres. J. F. Kennedylaan 3, B-9060 Zelzate (Belgium); Petrov, R.H. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Department of Materials Science and Engineering, Delft University of Technology, 2628 CD Delft (Netherlands)

    2015-04-10

    Third generation advanced high strength steels produced via quenching and partitioning (Q&P) treatment are receiving increased attention. A 0.25C–3Mn–1.5Si–0.023 Al steel was subjected to Q&P processing (with varying partitioning temperature and time) resulting in the formation of complex multi-phase microstructures. The effect of Q&P parameters on the microstructure and morphology of microconstituents was analyzed. Mechanical properties of the material and of its individual microconstituents were studied via tensile testing and nanoindentation on individual microconstituents, which were identified a priori by electron back-scattered diffraction analysis. Special attention is paid to the effect of the morphology of retained austenite on its transformation stability. In situ tensile tests and digital image correlation analysis were performed to study deformation behavior of the Q&P processed steel at the micro-scale with respect to the local microstructure. The effect of local microstructure and properties of individual phases on the degree of strain partitioning is discussed.

  4. Influence of plastic deformation on structure and mechanical properties of stainless steel type X5CrNi18-10

    W. Ozgowicz

    2008-07-01

    Full Text Available Purpose: The paper analyzes the influence of the degree of cold deformation on the structure and mechanical properties of austenitic stainless steel X5CrNi18-10.Design/methodology/approach: The investigations included observations of the structure on a light microscope, researches of mechanical properties in a static tensile test and microhardness measurements. The analysis of the phase composition was carried out on the basis of X-ray researches. In the qualitative X-ray analysis the comparative method was applied.Findings: Plastic deformation in deep drawing process of container from investigated austenitic stainless steel induced in its structure martensitic transformation ? ? ?.Research limitations/implications: The X-ray phase analysis in particular permitted to disclose and identify the main phases on the structure of the investigated steel after its deformation within the range 10%50%.Practical implications: The analysis of the obtained results permits to state that the degree of deformation has a significant influence on the structure and mechanical properties of the investigated steels. Besides, a good correlation was found between changes of the structure and the effects of investigations of the mechanical properties.Originality/value: The analytic dependence of the yield point of the investigated steel on the draft degree in deep pressing process has been confirmed. Revealing this relation is of essential practical importance for the technology of sheetmetal forming of austenitic steel.

  5. Deformable Nanolaminate Optics

    Olivier, S S; Papavasiliou, A P; Barbee, T W; Miles, R R; Walton, C C; Cohn, M B; Chang, K

    2006-05-12

    We are developing a new class of deformable optic based on electrostatic actuation of nanolaminate foils. These foils are engineered at the atomic level to provide optimal opto-mechanical properties, including surface quality, strength and stiffness, for a wide range of deformable optics. We are combining these foils, developed at Lawrence Livermore National Laboratory (LLNL), with commercial metal processing techniques to produce prototype deformable optics with aperture sizes up to 10 cm and actuator spacing from 1 mm to 1 cm and with a range of surface deformation designed to be as much as 10 microns. The existing capability for producing nanolaminate foils at LLNL, coupled with the commercial metal processing techniques being used, enable the potential production of these deformable optics with aperture sizes of over 1 m, and much larger deformable optics could potentially be produced by tiling multiple deformable segments. In addition, based on the fabrication processes being used, deformable nanolaminate optics could potentially be produced with areal densities of less than 1 kg per square m for applications in which lightweight deformable optics are desirable, and deformable nanolaminate optics could potentially be fabricated with intrinsically curved surfaces, including aspheric shapes. We will describe the basic principles of these devices, and we will present details of the design, fabrication and characterization of the prototype deformable nanolaminate optics that have been developed to date. We will also discuss the possibilities for future work on scaling these devices to larger sizes and developing both devices with lower areal densities and devices with curved surfaces.

  6. Effects of pressure and temperature at deformation in conditions of uniform compression on physical-mechanical properties of titanium in the range of 77...800 K

    Influence of deformation at 25% under uniform compression at pressure of 22 and 16.5 kbar at 77 K and 12 and 8 kbar at 300 K by using quasi hydroextrusion with counter pressure (QHEC) and without counter pressure (QHE) on physical-mechanical properties of titanium VT1-0 in the range of 77...800 K was investigated. It was shown, that two-stage character of dependence mechanical properties versus temperature in initial state (temperature-dependent in the range of 77...600 K and athermal in the range of 600...800 K) after deformation QHE and QHEP changed to one-stage and temperature-dependent character in the entire temperature range. It was shown that deformation under uniform pressure result in increase of strength in the range of 77...800 K and decrease the stacking fault energy of titanium. That is an addition factor of hardening besides increasing the density of deformation defects. It was found that uniform compression realized under higher pressures leads to less hardening and less accumulation of deformation defects. This associated with activation of recovery processes

  7. Microstructural evolution and mechanical properties of cryomilled nanograined near Al-5083 alloy following deformation processing

    Kaisar, Khan Hasib

    Nanocrystalline Al-Mg alloys are being considered for light weight transportation applications because they possess significantly higher strength than the conventional coarse grained alloys. Failure strengths higher than 1000 MPa have been reported for Al-5083 alloy at New Mexico Tech, which are almost double the strength of commercial precipitation strengthened Al-alloys. Unfortunately, the ductility tends to exhibit inverse relationship to strength and therefore there is a need to find ways to increase the ductility while maintaining high strength. In this work, we utilize a near Al-5083 alloy that was cryomilled for 24 hours in liquid nitrogen environment and consolidated by vacuum hot-pressing. The as-atomized Al-Mg powder was especially fabricated to minimize undesired impurity content to prevent premature fracture from intermetallic particles. It turned out that the final composition was slightly lower in Mn and Mg content and so the alloy is better designated as a near Al-5083 alloy. The as-vacuum hot pressed material had poor ductility because of inadequate prior-particle bonding, and therefore was subjected to deformation processing using low strain-rate extrusion at elevated temperatures. Both the strain-rate and temperature of extrusion were varied in an effort to obtain a good combination of tensile strength and ductility. In addition, the samples were annealed following extrusion in order to reduce residual stresses. The microstructure of extruded samples were characterized using a combination of electron microscope and X-ray diffraction techniques, and revealed a multi-scale morphology that could be binned into three different sizes of grains: i) those less than 100 nm that were analyzed using the X-ray based Williamson-Hall technique and transmission electron microscopy (TEM), ii) grain sizes in the 100-300 nm regime that were best revealed using TEM and scanning electron microscope (SEM) based electron-backscatter diffraction (EBSD) techniques, and, iii) elongated larger grains with lengths in the range 3 to 7 ?m that were observed using EBSD. Room temperature tensile tests with small tensile samples indicated that ultimate strengths in the range 740-760 MPa and elongation to failure better than 2.5%. These data could be produced reproducibly following extrusion at 400 C at an average strain rate of 0.05/sec, and fractography revealed a rough topography with large pull out regions that consisted of typical ductile dimple void growth at the 200-500 nm scale, while in other regions the dimples were very shallow that would suggest failure with little energy loss likely in regions of nanograins less than 100 nm. The combination of strength and ductility in the material are some of the best that have been reported for Al-5083 alloys, and likely a result of the multi-scale microstructure resulting from processing through the cryomilling and extrusion plus annealing procedures.

  8. Inferring strength and deformation properties of hot mix asphalt layers from the GPR signal: recent advances

    Tosti, Fabio; Benedetto, Andrea; Bianchini Ciampoli, Luca; Adabi, Saba; Pajewski, Lara

    2015-04-01

    The great flexibility of ground-penetrating radar has led to consider worldwide this instrument as an effective and efficient geophysical tool in several fields of application. As far as pavement engineering is concerned, ground-penetrating radar is employed in a wide range of applications, including physical and geometrical evaluation of road pavements. Conversely, the mechanical characterization of pavements is generally inferred through traditional (e.g., plate bearing test method) or advanced non-destructive techniques (e.g., falling weight deflectometer). Nevertheless, measurements performed using these methods, inevitably turn out to be both much more time-consuming and low-significant whether compared with ground-penetrating radar's potentials. In such a framework, a mechanical evaluation directly coming from electromagnetic inspections could represent a real breakthrough in the field of road assets management. With this purpose, a ground-penetrating radar system with 600 MHz and 1600 MHz center frequencies of investigation and ground-coupled antennas was employed to survey a 4m×30m flexible pavement test site. The test area was marked by a regular grid mesh of 836 nodes, respectively spaced by a distance of 0.40 m alongside the horizontal and vertical axes. At each node, the elastic modulus was measured using a light falling weight deflectometer. Data processing has provided to reconstruct a 3-D matrix of amplitudes for the surveyed area, considering a depth of around 300 mm, in accord to the influence domain of the light falling weight deflectometer. On the other hand, deflectometric data were employed for both calibration and validation of a semi-empirical model by relating the amplitude of signal reflections through the media along fixed depths within the depth domain considered, and the Young's modulus of the pavement at the evaluated point. This statistically-based model is aimed at continuously taking into account alongside the depth of investigation, of both the different strength provision of each layer composing the hot mix asphalt pavement structure, and of the attenuation occurring to electromagnetic waves during their in-depth propagation. Promising results are achieved by matching modelled and measured elastic modulus data. This continuous statistically-based model enables to consider the whole set of information related to each single depth, in order to provide a more comprehensive prediction of the strength and deformation behavior of such a complex multi-layered medium. Amongst some further developments to be tackled in the near future, a model improvement could be reached through laboratory activities under controlled conditions and by adopting several frequency bandwidths suited for purposes. In addition, the perspective to compare electromagnetic data with mechanical measurements retrieved continuously, i.e., by means of specifically equipped lorries, could pave the way to considerable enhancements in this field of research. Acknowledgements - This work has benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

  9. Mechanical and service properties of low carbon steels processed by severe plastic deformation

    J. Zrnik

    2009-07-01

    Full Text Available The structure and properties of the 0,09% C-Mn-Si-Nb-V-Ti, 0,1% C-Mn-V-Ti and 0,09% C-Mo-V-Nb low-carbon steels were studied after cold equal-channel angular pressing (ECAP. ECAP leads to the formation of partially submicrocrystalline structure with a grain size of 150 – 300 nm. The submicrocrystalline 0,09% C-Mn-Si-Nb-V-Ti steel compared with the normalized steel is characterized by Re higher more than by a factor of 2 and by the impact toughness higher by a factor of 3,5 at a test temperature of -40°C. The plasticity in this case is somewhat lower. The high-strength state of the submicrocrystalline 0,1% C-Mn-V-Ti and 0,09% C-Mo-V-Nb steels after ECAP is retained up to a test temperature of 500°C. The strength properties at 600°C (i.e. the fire resistance of these steels are higher by 20-25% as compared to those of the undeformed steels. The strength of the 0,09% C-Mo-V-Nb steel at 600°C is substantially higher than that of the 0,1% C-Mn-V-Ti steel.

  10. Mechanical properties and microstructure evolution of 1050 aluminum severely deformed by ECAP to 16 passes

    Variation of mechanical properties and microstructure evolution in 1050 aluminum processed by equal channel angle pressing are investigated using Route BC and up to 16 passes. Micro hardness and compression testing were used to evaluate mechanical properties, whereas electron back scattered diffraction (EBSD) was used to document the variation of cell size and misorientation angle with number of passes. The hardness and yield strength exhibited an instant increase by a factor of about 2.75 and 2.96, respectively, compared to the annealed state, after only the first pass. It was found that the cell size gradually decreased with number of passes and attained an average value of about 0.6 μm in the face plane (normal to the extrusion direction), and 0.85 μm in the flow plane (parallel to the extrusion direction) after the sixteenth pass. The average misorientation angle evolved in both the face and flow planes ended up to about 27 deg. and 26 deg., respectively

  11. Deformation and fracture properties in neutron irradiated pure Mo and Mo alloys

    Byun, T. S.; Li, M.; Cockeram, B. V.; Snead, L. L.

    2008-05-01

    The effect of neutron irradiation on the mechanical properties of select molybdenum materials, unalloyed low carbon arc-cast (LCAC) Mo, Mo-0.5% Ti-0.1% Zr (TZM) alloy, and oxide dispersion-strengthened (ODS) Mo alloy, was characterized by analyzing the temperature dependence of mechanical properties. This study assembles the tensile test data obtained through multiple irradiation and post-irradiation experiments, in which tensile specimens were irradiated up to 13.1 dpa at 80-1000 C and tested at -194 to 1000 C. Irradiation at 80-609 C increased yield stress significantly, up to 170%, while the increase of yield stress after irradiation at 784-936 C was not significant. The plastic instability stress was strongly dependent on test temperature but was nearly independent of irradiation dose and temperature. The true fracture stress showed weak dependences on test temperature, irradiation dose and temperature when ductile failure occurred. Among the test materials the stress-relieved ODS material in the longitudinal direction (ODS-LSR) displayed the highest resistance to irradiation embrittlement due to its relatively high fracture stress. The critical temperature for shear failure (CTSF) was defined and evaluated for the test materials and the CTSF values were compared with the ductile-to-brittle transition temperatures (DBTT) based on ductility data.

  12. Experiment and theory of a drift wave in the levitated octupole

    A very coherent 30 kHz drift wave is observed in the Levitated Toroidal Octupole at the University of Wisconsin - Madison. The density and floating potential fluctuations have a well-defined spatial structure in the poloidal magnetic field. Radially the wave has a standing wave structure with amplitude peaked in regions of locally bad magnetic curvature. Poloidally the wave has a standing wave structure with odd symmetry; nodes are located in the regions of locally good magnetic curvature. The wave propagates toroidally in the electron diamagnetic drift direction with a wavelength of 20 centimeters. No changes occur in the wave structure as the plasma is varied over three orders of magnitude in density and beta

  13. Search for the two-phonon octupole vibrational state in 208Pb

    We have performed an experiment to search for the two-phonon octupole vibrational state in 208Pb. Thick targets of 208Pb, 209Bi, 58,64Ni, and 160Gd were bombarded with 1305 MeV beams of 208Pb supplied by the ATLAS accelerator facility at Argonne. Gamma rays were measured using the Argonne-Notre Dame BGO gamma ray facility, consisting of 12 Compton suppressed Ge detectors surrounding an array of 50 BGO scintillators. We have identified some 30 known ? rays from 208Pb in coincidence spectra gated on low-lying transitions in 208Pb. In addition, after unfolding these spectra for Compton response, we observe broad coincident structures in the energy region expected for the decay of 2-phonon states. Furthermore, we have confirmed the placement of a previously observed 2485 keV ? ray in 207Pb and find no evidence consistent with the placement of this line in 208Pb. (orig.)

  14. Experimental investigation of plasma resistivity and ohmic heating in the octupole with toroidal magnetic field

    Plasma resistivity parallel to the magnetic field in the Wisconsin small octupole with toroidal magnetic field is investigated experimentally. A method is developed to use the flux surface constant, current density divided by magnetic field magnitude, to make possible the measurement of the average resistivity on a flux surface. An heuristic model for resistivity based on the neoclassical effects of Coulomb collisions and particle trapping in the magnetic mirrors is modified to also include neutral collisions and the reduction, caused by the parallel electric field, of mirror trapping. The scaling of resistivity with plasma and field parameters in this model is determined by the collisionality of the plasma with respect to the frequency of an average particle's encounters with the magnetic field maxima. The regimes are collisional, collisionless and intermediate or plateau. The local ohmic heating rate and plasma current density and their integrals over the experiment's volume are calculated

  15. Petrophysical Properties of Sandstones Containing Deformation Bands Versus Those With Fractures: the Importance of Grain Contact Strength to Fault-Zone Structure

    Schneider, J. R.; Tobin, H. J.; Goodwin, L. B.

    2010-12-01

    In upper crustal fault zones, the majority of slip accumulates within a fault core, which is surrounded by a less deformed damage zone. Both the width and structural character of the damage zone affect its mechanical and hydrologic properties. Fault-related deformation can change rock mechanical properties, causing stress orientations to rotate in fault damage zones, and affecting seismicity over time. In addition, the types, densities, and orientations of structures in fault zones exert a first-order control on fault-zone permeability structure, permeability anisotropy, and flow pathways. For example, open-fracture damage zones enhance fault-parallel flow, whereas cataclastic deformation band networks slow flow in every direction except parallel to the line of intersection between bands. To improve our understanding of controls on damage zone character, we explored relationships between fault-zone structure and lithologic characteristics such as porosity and cement mineralogy in faulted quartz-rich sandstones. The sandstones chosen from fault sites in the Jurassic Navajo and Entrada sandstones in Utah, and the Cretaceous Mesaverde sandstone in Wyoming, exhibit a wide range in porosity. Samples collected include even greater variability in cements, from clay coatings on grains to patchy carbonate cement to grain-bridging quartz overgrowths and iron oxide cements. These variables demonstrably influence damage zone character, resulting in fractures in some locations and deformation bands in others (even within a single fault zone) and affecting deformation-band damage zone width. They likely influenced grain-contact strength also. Because ultrasonic velocity and related elastic moduli also vary with grain-contact strength, we measured P and S wave velocities as a function of confining pressure to 20 MPa as a sensitive proxy for grain-contact strength. More than 40 samples, including both host rock and rock with deformation bands, have been analyzed. Samples containing deformation bands display different ultrasonic velocities than adjacent samples lacking deformation bands. These data are used to evaluate the relative importance of the variables affecting deformation in clastic rocks. Establishing a quantitative link between fault structures, cements, porosity, and lithology and ultrasonic velocity will ultimately allow results to be directly applied to borehole geophysics and seismic reflection studies to improve prediction of fault-zone characteristics and fluid flow properties in quartz-rich sandstone reservoirs.

  16. Mechanical Properties and Fractographic Analysis of High Manganese Steels After Dynamic Deformation Tests

    Jabłońska M.B.

    2014-10-01

    Full Text Available Since few years many research centres conducting research on the development of high-manganese steels for manufacturing of parts for automotive and railway industry. Some of these steels belong to the group of AHS possessing together with high strength a great plastic elongation, and an ideal uniform work hardening behavior. The article presents the dynamic mechanical properties of two types of high manganese austenitic steel with using a flywheel machine at room temperature with strain rates between 5×102÷3.5×103s?–1. It was found that the both studied steels exhibit a high sensitivity Rm to the strain rate. With increasing the strain rate from 5×102 to 3.5×103s?–1 the hardening dominates the process. The fracture analysis indicate that after dynamic test both steel is characterized by ductile fracture surfaces which indicate good plasticity of investigated steels.

  17. Deformation and Fracture Properties in Neutron Irradiated Pure Mo and Mo Alloys

    Byun, Thak Sang [ORNL; Li, Meimei [ORNL; Cockeram, Brian V [Bechtel-Bettis, Inc.; Snead, Lance Lewis [ORNL

    2008-01-01

    The effect of neutron irradiation on the mechanical properties of select molybdenum materials, pure low carbon arc-cast (LCAC) Mo, Mo-0.5% Ti-0.1% Zr (TZM) alloy, and oxide dispersion-strengthened (ODS) Mo alloy, was characterized by analyzing the temperature dependence of mechanical properties. This study assembles the tensile test and analysis data obtained through multiple series of irradiation and post-irradiation experiments. Tensile specimens in stress-relieved conditions with longitudinal (LSR) and transverse (TSR) directions were irradiated in high flux isotope reactor (HFIR) at temperatures ranging 270 to 1100oC to 0.6 -13.1 dpa. Also, the recrystallized LCAC Mo specimens in the longitudinal direction (LR) were also irradiated up to 0.28 dpa at ~80oC. Tensile tests were performed at temperatures ranging from -194 oC to 1400oC. Analysis results indicate that the irradiation at temperatures below 700oC increased strength significantly, up to 170%, while the increase of yield stress by irradiations at higher temperature was not significant. The plastic instability stress was strongly dependent on test temperature but was nearly independent of irradiation dose and temperature. The true fracture stress was dependent on test temperature to a lesser degree than was the yield stress and plastic instability stress. It was also slightly impacted by irradiation, depending on both irradiation and test temperatures. Brittle fracture often occurred in the LSR specimens tested at room temperature or lower after low temperature irradiation, while it was observed in many irradiated TSR specimens over the whole test temperature range. The ODS-LSR specimens showed the highest resistance to irradiation embrittlement due to relatively higher fracture stress. The critical temperature for shear failure (CTSF) was defined and evaluated for the materials, and the CTSF values were compared with the ductile to brittle transition temperatures (DBTT) based on ductility data.

  18. Influence of alloying and testing conditions on mechanical properties and deformation behavior of 〈100〉 tungsten-based single crystals

    The results of the pressure testing of mechanical properties of single crystals of pure tungsten and low-alloyed alloys W–2Re and W–1Re–1Mo (wt%) with a crystallographic orientation 〈100〉 which were prepared by plasma-arc melting are summarized. The effect of alloying and the deformation rate on these properties have also been investigated and the fracture surfaces of the individual single crystals have been evaluated with the aid of the photometric method. The differences in the deformation behavior of pure tungsten and W–Re and W–1Mo–Re alloys were observed, which relate to the particularities of rhenium and molybdenum action in the tungsten solid solution. It can be seen from the observed results that tungsten alloying with low rhenium and molybdenum contents decreased all mechanical properties when applying the deformation rate of 0.2 mm/min. The biggest decrease was observed for the offset yield strength value. When testing with the deformation rate of 2 mm/min, the strength limit of the W–2Re alloy increased to 2013 MPa, while Rpt0.2 decreased by 33% in comparison with the pure tungsten single crystal. However, the εr value remained at the same level ∼30%. In the W–1Re–1Mo single crystal, the Rpt0.2 and Rmt values decreased, while εr increased slightly

  19. Effect of plastic deformation on the electrophysical properties and structure of YBa2Cu3O y ceramics subjected to low-temperature treatment

    Bobylev, I. B.; Zyuzeva, N. A.; Degtyarev, M. V.; Pilyugin, V. P.

    2015-12-01

    The electrophysical properties and structure of HTSC YBa2Cu3O y compound (123) subjected to plastic deformation by shear under a pressure of 1.7 GPa have been studied. After deformation, the electrophysical properties of samples prepared using the traditional ceramic technology were found to deteriorate. Subsequent annealing at 930°C cannot restore the critical current density ( j c) in low magnetic fields to initial magnitudes; however, in magnetic fields of more than 0.1 T, the j c magnitude increases compared to that for the starting state. The deformation of 123 ceramics treated at 200°C in a humid atmosphere that has undergone phase transformation into the 124 tetragonal phase allows its structure and electrophysical properties to be restored. In this case, the reverse transformation of phase 124 into 123, which is accompanied by the recrystallization of the material, takes place. The combination of low-temperature treatment and high shearing deformation leads to the appearance of texture and an increase of j c, in particular in high magnetic fields.

  20. Geometrical and mechanical properties of the fractures and brittle deformation zones based on the ONKALO tunnel mapping, 4390-4990 m tunnel chainage and the technical rooms

    Simelius, C. [Poeyry Finland Oy, Vantaa (Finland)

    2014-04-15

    In this report, the rock mechanics parameters of fractures and brittle deformation zones have been estimated in the vicinity of the ONKALO underground research facility at the Olkiluoto site, western Finland. This report is an extension of two previously published reports describing the geometrical and mechanical properties of the fractures and brittle deformation zones based on ONKALO tunnel mapping from tunnel chainages 0-2400 m (Kuula 2010) and 2400-4390 m (Moenkkoenen et al. 2012). This updated report makes use of mapping data from tunnel chainage 4390-4990 m, including the technical rooms located at the -420 m below the sea level. Analysis of the technical rooms is carried out by dividing the premises according to depth into three sections: the demonstration tunnel level, the technical rooms level and the -457 level. The division is executed in order to define the fracture properties in separate areas and to compare the properties with other technical rooms levels. Drillhole data from holes OL-KR1...OL-KR57 is also examined. This report ends the series of three parameterization reports. The defined rock mechanics parameters of the fractures are based on the rock engineering classification quality index, Q', which incorporates the RQD, Jn, Jr and Ja values. The friction angle of the fracture surfaces is estimated from the Jr and Ja numbers. No new data from laboratory joint shear and normal tests was available at the time of the report. The fracture wall compressive strength (JCS) data is available from the chainage range 1280-2400 m. New data for fracture wall compressive strength is not available although new Schmidt hammer measurements were performed in order to obtain the ratio of the intact rock mass vs. an intact brittle deformation zone. Estimation of the mechanical properties of the 23 brittle deformation zones (BDZ) is based on the mapped Q' value, which is converted into the GSI value in order to estimate the strength and deformability properties. Components of the mapped Q' values are either from the ONKALO or the drill cores depending on the availability of intersections. The location and size of the brittle deformation zones are based on the latest interpretation (Aaltonen et al. expected in 2014). New laboratory data for the intact rock strength of the brittle deformation zones is not available. (orig.)

  1. Geometrical and mechanical properties of the fractures and brittle deformation zones based on the ONKALO tunnel mapping, 4390-4990 m tunnel chainage and the technical rooms

    In this report, the rock mechanics parameters of fractures and brittle deformation zones have been estimated in the vicinity of the ONKALO underground research facility at the Olkiluoto site, western Finland. This report is an extension of two previously published reports describing the geometrical and mechanical properties of the fractures and brittle deformation zones based on ONKALO tunnel mapping from tunnel chainages 0-2400 m (Kuula 2010) and 2400-4390 m (Moenkkoenen et al. 2012). This updated report makes use of mapping data from tunnel chainage 4390-4990 m, including the technical rooms located at the -420 m below the sea level. Analysis of the technical rooms is carried out by dividing the premises according to depth into three sections: the demonstration tunnel level, the technical rooms level and the -457 level. The division is executed in order to define the fracture properties in separate areas and to compare the properties with other technical rooms levels. Drillhole data from holes OL-KR1...OL-KR57 is also examined. This report ends the series of three parameterization reports. The defined rock mechanics parameters of the fractures are based on the rock engineering classification quality index, Q', which incorporates the RQD, Jn, Jr and Ja values. The friction angle of the fracture surfaces is estimated from the Jr and Ja numbers. No new data from laboratory joint shear and normal tests was available at the time of the report. The fracture wall compressive strength (JCS) data is available from the chainage range 1280-2400 m. New data for fracture wall compressive strength is not available although new Schmidt hammer measurements were performed in order to obtain the ratio of the intact rock mass vs. an intact brittle deformation zone. Estimation of the mechanical properties of the 23 brittle deformation zones (BDZ) is based on the mapped Q' value, which is converted into the GSI value in order to estimate the strength and deformability properties. Components of the mapped Q' values are either from the ONKALO or the drill cores depending on the availability of intersections. The location and size of the brittle deformation zones are based on the latest interpretation (Aaltonen et al. expected in 2014). New laboratory data for the intact rock strength of the brittle deformation zones is not available. (orig.)

  2. Microstructure and Mechanical Properties of Ti-TiB Based Short-Fiber Composite Materials Manufactured by Casting and Subjected to Deformation Processing

    Gaisin, R. A.; Imayev, V. M.; Imayev, R. M.; Gaisina, É. R.

    2015-10-01

    The microstructure and mechanical properties of Ti-TiB based short-fiber composite materials manufactured by casting and subjected to deformation processing are investigated. Commercially pure VT1-0 titanium and two-phase VT8 alloys are used for matrix alloys. It is established that the short-fiber composite materials comprising about 10 vol.% of titanium monoboride can be successfully prepared by conventional casting. Regimes of deformation processing of the composite materials providing reorientation of titanium monoboride fibers with retention of a high length-to-diameter ratio are developed. The composite materials after deformation processing demonstrate higher strength characteristics and, as demonstrated for the VT8 based composite, high-temperature strength compared to the matrix material without a radical reduction of ductility.

  3. Mechanical properties and deformation mechanisms in Fe-xMn-3.2Al-0.2C (12≤x≤43) alloys

    Microstructure and mechanical properties of Fe-xMn-3,2 Al-0,23 C alloys with 12≤x≤43 (mass %) at 77 and 290 K have been studied to determine the mechanisms controlling plastic deformation. Austenitic alloys (Mn≥22) show an increase of elongation to failure with decreasing temperature of testing (inverse ductility). This behavior has been related to deformation of deformation twins, which is favored at 77 K. Alloys with manganese content lower than 17% present a two-phase microstructure (α' + γ). The martensite volume fraction increases as the manganese content decreases. These alloys show a los of ductility, especially at 77 K. In contrast to austenitic alloys, this different mechanical behavior has been associated with a TRIP mechanism (transformation-induced plasticity). (Author) 11 refs

  4. Electrical and optical properties of stacking faults introduced by plastic deformation in 4H-SiC

    The electrical and optical properties of stacking faults (SFs) introduced by plastic deformation in 4H-SiC were studied by Electron Beam Induced Current (EBIC) and cathodoluminescence (CL) methods. Partial dislocations and stacking faults in the (0001) glide planes perpendicular to the surface were introduced in n-type 4H-SiC under a well-controlled state of stress by cantilever bending at 550°C. CL measurements allow determining the multiplicity of the SFs (single or double). It is observed that the overwhelming majority of stacking faults are double Shockley type SFs (CL emission at 504 nm) that correlates well with previously published high resolution transmission electron microscopy (HRTEM) investigations. However, single Shockley type SFs (CL emission at 422 nm) of much smaller lengths are also observed in some areas near the scratched region from where the defects are nucleated. This suggests that the velocity of partial dislocation pairs under a given applied stress could be higher than that of single partial dislocations. It is also shown that in the EBIC mode, SFs produce a strong bright contrast, which can be explained by considering the SFs in 4H-SiC to be quantum wells of II type

  5. Influence of the pearlite fineness on the mechanical properties, deformation behavior, and fracture characteristics of carbon steel

    Izotov, V. I.; Pozdnyakov, V. A.; Luk'yanenko, E. V.; Usanova, O. Yu.; Filippov, G. A.

    2007-05-01

    Specific features of plastic deformation and tensile failure of a plain carbon ( C = 0.62%) pearlitic-ferritic steel with various pearlite fineness have been investigated. It is shown that the steels with coarse lamellar pearlite and fine lamellar pearlite have similar strain-hardening coefficients, but the relative elongation of the former steel is higher. Deformation results in a uniform dislocation distribution in the fine pearlite and in the formation of a cellular substructure in the coarse pearlite. It is established that the fine pearlite undergoes plastic deformation and ductile failure as a single structure, while the coarse pearlite exhibits a structure discontinuity upon deformation. A model of microplastic pearlite deformation and the initial stage of macroplastic pearlite deformation is proposed. It is established that the strain-hardening coefficient of pearlite at the initial deformation stage does not depend on its dispersity. A size effect, which manifests itself in the dependence of the dislocation structure formed in the ferrite interlayers on their thickness, is shown to be characteristic of pearlite deformation.

  6. Influence of processing temperature on microstructural and mechanical properties of high-alloyed single-phase steels subjected to severe plastic deformation

    An austenitic and a ferritic steel were subjected to severe plastic deformation at 20 and 450 deg. C up to equivalent strains of 32. The development of the microstructure and the mechanical properties have been investigated by capturing back-scattered electron micrographs and performing subsize tensile tests. For both steels, a steady state of the properties was observed above equivalent strains of 16. The results show clearly that the temperature influences both, microstructure and mechanical properties, whereas the type of material (ferritic, austenitic) plays an additional important role. Possible reasons for the observed differences are discussed

  7. Geometrical and mechanical properties of the fractures and brittle deformation zones based on ONKALO tunnel mapping, 0-2400 m tunnel chainage

    In this report, the rock mechanics parameters of fractures and brittle deformation zones in the vicinity of the ONKALO area have been estimated, the analysed data being from the ONKALO tunnel over the chainage range 0-2400 m. Some analysis has also been made based on core logging data from the drillholes OL-KR1-OL-KR40. At this stage, the main objective of the work is to obtain preliminary parameters for the rock mechanics simulations and the rock mechanics design. In this report, the rock mechanics parameters of the fractures are mainly associated with the rock engineering classification quality index, Q, which incorporates the RQD, Jn, Jr and Ja values. The friction angle of the fracture surfaces is estimated from the Jr and Ja numbers. The fracture wall compressive strength (JCS) has been systematically estimated for the chainage range 1280-2400 m using Schmidt hammer tests. So far, only a few laboratory direct shear tests have been conducted on fracture samples. Estimation of the mechanics properties of the brittle deformation zones (BDZ) is based on the mapped Q value, which is transformed to the GSI value in order to estimate strength and deformability properties. A component of the mapped Q values is from the ONKALO and another component is from the drill cores. The intact rock strength of the brittle deformation zones has been evaluated using Schmidt hammer tests. (orig.)

  8. Strong M1 components in 3-i?3-1 in nearly spherical nuclei: Evidence for isovector-octupole excitations

    An evaluation of data obtained in (n,n'?) experiments reveals strong M1 3-i ? 3-1 transitions in nuclei near the N=50 (92Zr, 94Mo and 96Mo), Z=50 (112Cd and 114Cd) and N=82 (144Nd) shell closures. The observed left angle 31- M1 3i- right angle matrix elements scale with the left angle 21+ parallel M1 parallel 2+ms right angle matrix elements, and the energy difference between the initial 3-i state and the 3-1 octupole phonon is proportional to the left angle 3-1 parallel E3 parallel 0+gs right angle matrix element. The possibility of assigning the states of interest as octupole mixed-symmetry states is discussed.

  9. Confinement properties of high energy density plasmas in the Wisconsin levitated octupole

    The confinement of particles and energy is critically dependent on the plasma-wall interaction. Results of a study detailing this interaction are presented. High power ICRF heated and gun afterglow plasmas were studied to detail the mechanisms determining particle and energy confinement. An extensive zero-D simulation code is used to assist in interpreting the experimental data. Physically reasonable models for plasma surface interactions, time dependent coronal treatment of impurities and multiple region treatment of neutrals are used in modeling the plasma. Extensive diagnostic data are used to verify the model. Non-heated plasmas decay from 28 to 3 eV allowing clear identification of wall impact energy thresholds for desorption and particle reflection. The charge state distribution of impurities verifies the reflux to plasma diffusion rate ratio. Close agreement between the simulation and experimental data is found

  10. Composite microstructural anisotropies in reservoir rocks: consequences on elastic properties and relation with deformation; Anisotropies microstructurales composites dans les roches reservoir: consequences sur les proprietes elastiques et relation a la deformation

    Louis, L.

    2003-10-15

    From diagenesis to tectonic stress induced deformation, rock microstructures always present some anisotropy associated with a preferential orientation, shape or spatial arrangement of its constituents. Considering the consequences anisotropy has on directional transport properties and compliance, as the geological history it carries, this approach has received a particular attention in numerous works. In this work, the microstructural features of various sedimentary rocks were investigated through direct observations and laboratory measurements in naturally deformed and undeformed blocks, samples being considered as effective media. All investigated samples were found to be anisotropic with respect to the physical properties we measured (i.e. ultrasonic P-wave velocity, magnetic susceptibility, electrical conductivity). Considering that P-wave velocities can be described by a second order tensor, we applied to the velocity data the same inversion procedure as the one routinely used in magnetic studies, which provided an efficient tool to estimate and compare these 3D anisotropies with respect to the original sample geographical position. In each case, we tried to identify as thoroughly as possible the microstructural source of the observed anisotropies, first by the mean of existing models, then through direct observations (optic and electronic microscopy). Depending on the rock investigated, anisotropy was found to be controlled by pore shape, intergranular contact distribution, preferentially oriented microcracks interacting with compaction pattern or pressure solution cleavages interacting with each other. The net result of this work is that P-wave velocity anisotropy can express the interaction between different microstructural features as well as their evolution during deformation. (author)

  11. Effect of deformation-induced martensite on the microstructure, mechanical properties and corrosion resistance of X5CrNi18-8 stainless steel

    W. Ozgowicz

    2010-05-01

    Full Text Available Purpose: The aim of the paper was to determine the effect of deformation-induced martensite on the microstructure, mechanical properties and corrosion resistance of X5CrNi18-8 austenitic steel.Design/methodology/approach: The investigations included observations of the microstructure on a light microscope, researches of mechanical properties in a static tensile test, microhardness measurements made by Vickerss method and corrosion resistance test examined using weight method. The analysis of the phase composition was carried out on the basis of X-ray researches. The amount of martensite ? in the obtained microstructures was investigated with ferritescope magnetic tester. The observations of the surface morphology after corrosive tests were carried out using Scanning Electron Microscope. The scope of this study was to achieve the correlations between the mechanical, corrosion and structural properties of cold rolled stainless steel.Findings: Plastic deformation in a cold working of austenitic stainless steel induced in its structure martensitic transformation ? ? ?. The occurrence of martensite ? in the investigated steel structure has an essential meaning in manufacturing process of forming sheet-metals from austenitic steel.Research limitations/implications: The X-ray phase analysis in particular permitted to disclose and identify the main phases on the structure of the investigated steel after its deformation within the range 10 - 70%. The results of the ferritescope measurements allowed determining the proportional part of ?` phases in the structure of investigated steel in the examined range of cold plastic deformation. The microscope observations of the surface samples subjected to corrosion resistance test in 30 wt% H2SO4 solutions permitted to evaluate kinds and the rate of corrosion damages.Originality/value: A wide range of practical applications of 18/8 steel sheets is warranted by both their high corrosion resistance and high plastic properties.

  12. THE EFFECT OF SUPERPLASTIC DEFORMATION ON THE TENSILE AND FATIGUE PROPERTIES OF Al-Li (8090) ALLOY

    Mcdarmaid, D.; Shakesheff, A.

    1987-01-01

    Superplastic deformation of the new generation of aerospace aluminium-lithium alloys has generated considerable interest in the aerospace industry not only with the potential savings in component weight and manufacturing costs but also for development of novel designs. Even though many papers have addressed the superplastic deformation characteristics of these alloys it is essential for their exploitation to determine and to understand the effect of the forming process on their mechanical pro...

  13. New results for the missing quantum numbers labelling the quadrupole and octupole boson basis

    The many 2k-pole boson states, |Nkvk?kIkMk) with k = 2, 3, realize the irreducible representation (IR) for the group reduction chains SU(2k + 1) R2k+1 R3 R2. They have been analytically studied and widely used for the description of nuclear systems. However, no analytical expression for the degeneracy d(k)v(I) of the R2k+1 IR, determined by the reduction R2k+1 R3, with k = 2, 3 is available. Thus, the number of distinct values taken by ?k has been so far obtained by solving some complex equations. Here we derive analytical expressions for the degeneracy d(k)v(I) (k = 2, 3), characterizing the octupole and quadrupole boson states, respectively. The merit of this work consists of the fact that it completes the analytical expressions for the 2k-pole boson basis for k = 2, 3. The general case of R2l+1 IR representation degeneracy is also presented and a compact analytical expression for d(l)v(I) is derived

  14. The decay of quadrupole-octupole $1^-$ states in $^{40}$Ca and $^{140}$Ce

    Derya, V; Aumann, T; Bhike, M; Endres, J; Gooden, M; Hennig, A; Isaak, J; Lenske, H; Löher, B; Pietralla, N; Savran, D; Tornow, W; Werner, V; Zilges, A

    2016-01-01

    Background: Two-phonon excitations originating from the coupling of two collective one-phonon states are of great interest in nuclear structure physics. One possibility to generate low-lying $E1$ excitations is the coupling of quadrupole and octupole phonons. Purpose: In this work, the $\\gamma$-decay behavior of candidates for the $(2_1^+\\otimes 3_1^-)_{1^-}$ state in the doubly-magic nucleus $^{40}$Ca and in the heavier and semi-magic nucleus $^{140}$Ce is investigated. Methods: $(\\vec{\\gamma},\\gamma')$ experiments have been carried out at the High Intensity $\\gamma$-ray Source (HI${\\gamma}$S) facility in combination with the high-efficiency $\\gamma$-ray spectroscopy setup $\\gamma^3$ consisting of HPGe and LaBr$_3$ detectors. The setup enables the acquisition of $\\gamma$-$\\gamma$ coincidence data and, hence, the detection of direct decay paths. Results: In addition to the known ground-state decays, for $^{40}$Ca the decay into the $3^-_1$ state was observed, while for $^{140}$Ce the direct decays into the $2...

  15. Suppression of Quadrupole and Octupole Modes in Red Giants Observed by Kepler *

    Stello, Dennis; Cantiello, Matteo; Fuller, Jim; Garcia, Rafael A.; Huber, Daniel

    2016-03-01

    An exciting new theoretical result shows that observing suppression of dipole oscillation modes in red giant stars can be used to detect strong magnetic fields in the stellar cores. A fundamental facet of the theory is that nearly all the mode energy leaking into the core is trapped by the magnetic greenhouse effect. This results in clear predictions for how the mode visibility changes as a star evolves up the red giant branch, and how that depends on stellar mass, spherical degree, and mode lifetime. Here, we investigate the validity of these predictions with a focus on the visibility of different spherical degrees. We find that mode suppression weakens for higher degree modes with a reduction in the quadrupole mode visibility of up to 49%, and no detectable suppression of octupole modes, in agreement with theory. We find evidence for the influence of increasing mode lifetimes on the visibilities along the red giant branch, in agreement with previous independent observations. These results support the theory that strong internal magnetic fields cause suppression of non-radial modes in red giants. We also find preliminary evidence that stars with suppressed dipole modes on average have slightly lower metallicity than normal stars.

  16. Core breaking and octupole low-spin states in $^{207}$ Tl

    We propose to study the low-spin level structure of the $^{207}$Tl nucleus populated by the $\\beta$- decay of $^{207}$Hg. While $^{207}$Tl is a single-proton hole nucleus, the majority of the observed states will have threeparticle structure thus requiring the breaking of the neutron or proton core, or a collective octupole phonon coupled to the single proton hole. Thus information will be obtained on the single particle orbitals in the vicinity of the N=126 and Z=82 magic numbers, and on the size of the shell gap. The results will be used to improve the predictive power of the shell model for more exotic nuclei as we move to lighter N=126 nuclei.The experiment will use the ISOLDE Decay station, and will take advantage of the $^{207}$Hg beam from the molten lead target. A test on the feasibility to produce $^{208}$Hg beam from the same target, with the aim to study the $\\beta$-decay into $^{208}$Tl, could be performed at the same time.

  17. Suppression of quadrupole and octupole modes in red giants observed by Kepler

    Stello, D; Fuller, J; Garcia, R A; Huber, D

    2016-01-01

    The asteroseismology of red giant stars has continued to yield surprises since the onset of high-precision photometry from space-based observations. An exciting new theoretical result shows that the previously observed suppression of dipole oscillation modes in red giants can be used to detect strong magnetic fields in the stellar cores. A fundamental facet of the theory is that nearly all the mode energy leaking into the core is trapped by the magnetic greenhouse effect. This results in clear predictions for how the mode visibility changes as a star evolves up the red giant branch, and how that depends on stellar mass, spherical degree, and mode lifetime. Here, we investigate the validity of these predictions with a focus on the visibility of different spherical degrees. We find that mode suppression weakens for higher degree modes with an average reduction in the quadrupole mode visibility of up to 49% for the least evolved stars in our sample, and no detectable suppression of octupole modes, in agreement w...

  18. Search for the two-phonon octupole vibrational state in 208Pb

    We performed an experiment to search for the two-phonon octupole vibrational state in 208Pb. Thick targets of 208Pb, 209Bi, 58,64Ni, and 160Gd were bombarded with 1305 MeV beams of were bombard 208Pb supplied by ATLAS. Gamma rays were detected using the Argonne-Notre Dame BGO gamma-ray facility, consisting of 12 Compton-suppressed germanium detectors surrounding an array of 50 BGO scintillators. We identified some 30 known gamma rays from 208Pb in the spectra gated by the 5- ? 3- and 3- ? 0+ transitions in 208Pb. In addition, after unfolding these spectra for Compton response, we observed broad coincident structures in the energy region expected for the 2-phonon states. Furthermore, we confirmed the placement of a 2485 keV line observed previously in 207Pb and find no evidence consistent with the placement of this line in 208Pb. We are currently in the process of investigating the origin of the broadened lines observed in the spectra, extracting the excitation probability of states in 208Pb, and determining the relative probability of mutual excitation and neutron transfer in this reaction. An additional experiment is also being performed to collect much higher statistics germanium-germanium coincidence data for the thick 208Pb target

  19. Search for the two-phonon octupole vibrational state in {sup 208}Pb

    Blumenthal, D.J.; Henning, W.; Janssens, R.V.F. [and others

    1995-08-01

    We performed an experiment to search for the two-phonon octupole vibrational state in {sup 208}Pb. Thick targets of {sup 208}Pb, {sup 209}Bi, {sup 58,64}Ni, and {sup 160}Gd were bombarded with 1305 MeV beams of were bombard {sup 208}Pb supplied by ATLAS. Gamma rays were detected using the Argonne-Notre Dame BGO gamma-ray facility, consisting of 12 Compton-suppressed germanium detectors surrounding an array of 50 BGO scintillators. We identified some 30 known gamma rays from {sup 208}Pb in the spectra gated by the 5{sup -} {yields} 3{sup -} and 3{sup -} {yields} 0{sup +} transitions in {sup 208}Pb. In addition, after unfolding these spectra for Compton response, we observed broad coincident structures in the energy region expected for the 2-phonon states. Furthermore, we confirmed the placement of a 2485 keV line observed previously in {sup 207}Pb and find no evidence consistent with the placement of this line in {sup 208}Pb. We are currently in the process of investigating the origin of the broadened lines observed in the spectra, extracting the excitation probability of states in {sup 208}Pb, and determining the relative probability of mutual excitation and neutron transfer in this reaction. An additional experiment is also being performed to collect much higher statistics germanium-germanium coincidence data for the thick {sup 208}Pb target.

  20. High spin states and evidence for octupole correlations in 117Xe

    High-spin states of 117Xe were investigated by means of in-beam ?-ray spectroscopic techniques via the reaction of 28Si bombarding a 92Mo target at beam energies of 100-120 MeV. A positive-parity rotational band decaying into the yrast negative-parity band by a series of enhanced E1 transitions was observed for the first time, implying the existence of octupole correlations in 117Xe. The B(E1) values increase with spin. The ?d5/2 band was firmly established up to 27/2+ and the B(M1)/B(E2) ratios were extracted from the relative intensities of ?-rays in this band. The previously known ?h11/2 and ?g7/2 [413]5/2+ ?=-1/2 bands were confirmed and extended up to high spins and two bandcrossings are observed in the latter at ??=0.33 and 0.44 MeV, respectively. The bandcrossings and configurations of these bands are discussed by TRS and CSM calculations. In a ?-?-t measurement, the 11/2- and 7/2- levels were identified as two isomers with half-lives of 59.420 ns and 16.58.0 ns, respectively. (orig.)

  1. Influence of disorder and deformation on the optical properties of a two-dimensional photonic crystal waveguide

    We investigate the effect of disorder and mechanical deformation on a two-dimensional photonic crystal waveguide. The dispersion characteristics and transmittance of the waveguide are studied using the finite element method. Results show that the geometric change of the dielectric material perpendicular to the light propagation direction has a larger influence on the waveguide characteristics than that parallel to the light propagation direction. Mechanical deformation has an obvious influence on the performance of the waveguide. In particular, longitudinal deformed structure exhibits distinct optical characteristics from the ideal one. Studies on this work will provide useful guideline to the fabrication and practical applications based on photonic crystal waveguides. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  2. Microstructures and mechanical properties of pure copper deformed severely by equal-channel angular pressing and high pressure torsion

    Lugo, N. [Department of Materials Science and Metallurgical Engineering, ETSEIB, Polytechnic University of Catalonia, Av. Diagonal 647, 08028 Barcelona (Spain)], E-mail: nayar.lugo@upc.edu; Llorca, N. [Department of Materials Science and Metallurgical Engineering, University of Barcelona, C/Marti i Franques 1-11, 08028 Barcelona (Spain)], E-mail: nullorca@ub.edu; Cabrera, J.M. [Department of Materials Science and Metallurgical Engineering, ETSEIB, Polytechnic University of Catalonia, Av. Diagonal 647, 08028 Barcelona (Spain); CTM Technical Center, Av. Bases de Manresa 1, 08242 Manresa (Spain)], E-mail: jose.maria.cabrera@upc.edu; Horita, Z. [Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan)], E-mail: horita@zaiko.kyushu-u-ac.jp

    2008-03-25

    Pure Cu of 99.98 wt.% purity has been processed at room temperature by diverse techniques of severe plastic deformation, namely equal-channel angular pressing (ECAP), high pressure torsion (HPT) and a combination of both in order to find out the evolution on the microstructural homogeneity for each of the processes and their combination. Starting with a grain size of {approx}60 {mu}m, severe plastic deformation has been introduced to the material while maintaining the sample dimensions unchanged through the processes of ECAP and HPT. A significant decrease in grain size was observed by transmission electronic microscopy (TEM). Microtensile and microhardness tests were carried out on the deformed material in the three processing conditions. A significant improvement of the tensile strength was promoted with admissible penalization on ductility.

  3. Boron nitride nanotubes reinforced aluminum composites prepared by spark plasma sintering: Microstructure, mechanical properties and deformation behavior

    Lahiri, Debrupa; Hadjikhani, Ali; Zhang, Cheng [Plasma Forming Lab, Advanced Materials Engineering Research Institute (AMERI), Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States); Xing, Tan; Li, Lu Hua; Chen, Ying [Institute for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, VIC 3216 (Australia); Agarwal, Arvind, E-mail: agarwala@fiu.edu [Plasma Forming Lab, Advanced Materials Engineering Research Institute (AMERI), Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States)

    2013-07-01

    Boron nitride nanotubes (BNNT) reinforced aluminum based composites are synthesized by spark plasma sintering (SPS). The concentration of BNNT is varied as 0, 2 and 5 vol% in the aluminum matrix. Micro-pillar compression testing revealed that Al–5 vol% BNNT has yield strength and compressive strength as 88 MPa and 216 MPa respectively, which is more than 50% improvement over unreinforced Al. BNNT play an active role in strengthening Al matrix through effective load bearing and transfer by crack bridging and sword in sheath mechanisms. Cold rolling of Al–5 vol% BNNT with 75% thickness reduction in a single pass exhibited high deformability without cracking or disintegration. The deformation is dominated by slip signifying ductile behavior in sintered Al with and without BNNT. BNNT survives the extreme temperature and pressure conditions during SPS processing and heavy deformation during cold rolling.

  4. The Contribution of Plastic Deformations to the Adhesion Properties of Polymer-Polymer Contacts Studied with the Surface Force Apparatus.

    Heuberger, Manfred; Luengo, Gustavo; Israelachvili, Jacob

    1996-03-01

    The energy dissipated in a loading-unloading process of a polymer-polymer contact is commonly referred to as adhesion hysteresis. Adhesion hysteresis contains contributions from different sources one of which is plastic deformation. We have studied in dry air the plastic deformation of two initially curved surfaces of Poly(Buthyl-Methacrylate) (PBMA) which has itUs Tg close to room temperature. Using the Surface Force Apparatus we have observed plastic deformations including the formation of a polymer-meniscus exhibiting cavitation-like effects on separation. The results are compared to the case of Poly(Methyl-Methacrylate) (PMMA) which is well below itUs Tg at room temperature.

  5. Boron nitride nanotubes reinforced aluminum composites prepared by spark plasma sintering: Microstructure, mechanical properties and deformation behavior

    Boron nitride nanotubes (BNNT) reinforced aluminum based composites are synthesized by spark plasma sintering (SPS). The concentration of BNNT is varied as 0, 2 and 5 vol% in the aluminum matrix. Micro-pillar compression testing revealed that Al–5 vol% BNNT has yield strength and compressive strength as 88 MPa and 216 MPa respectively, which is more than 50% improvement over unreinforced Al. BNNT play an active role in strengthening Al matrix through effective load bearing and transfer by crack bridging and sword in sheath mechanisms. Cold rolling of Al–5 vol% BNNT with 75% thickness reduction in a single pass exhibited high deformability without cracking or disintegration. The deformation is dominated by slip signifying ductile behavior in sintered Al with and without BNNT. BNNT survives the extreme temperature and pressure conditions during SPS processing and heavy deformation during cold rolling

  6. q -deformed statistical-mechanical property in the dynamics of trajectories en route to the Feigenbaum attractor

    Robledo, A.; Moyano, L. G.

    2008-03-01

    We demonstrate that the dynamics toward and within the Feigenbaum attractor combine to form a q -deformed statistical-mechanical construction. The rate at which ensemble trajectories converge to the attractor (and to the repellor) is described by a q entropy obtained from a partition function generated by summing distances between neighboring positions of the attractor. The values of the q indices involved are given by the unimodal map universal constants, while the thermodynamic structure is closely related to that formerly developed for multifractals. As an essential component in our demonstration we expose, in great detail, the features of the dynamics of trajectories that either evolve toward the Feigenbaum attractor or are captured by its matching repellor. The dynamical properties of the family of periodic superstable cycles in unimodal maps are seen to be key ingredients for the comprehension of the discrete scale invariance features present at the period-doubling transition to chaos. Elements in our analysis are the following. (i) The preimages of the attractor and repellor of each of the supercycles appear entrenched into a fractal hierarchical structure of increasing complexity as period doubling develops. (ii) The limiting form of this rank structure results in an infinite number of families of well-defined phase-space gaps in the positions of the Feigenbaum attractor or of its repellor. (iii) The gaps in each of these families can be ordered with decreasing width in accordance with power laws and are seen to appear sequentially in the dynamics generated by uniform distributions of initial conditions. (iv) The power law with log-periodic modulation associated with the rate of approach of trajectories toward the attractor (and to the repellor) is explained in terms of the progression of gap formation. (v) The relationship between the law of rate of convergence to the attractor and the inexhaustible hierarchy feature of the preimage structure is elucidated. (vi) A "mean field" evaluation of the atypical partition function, a thermodynamic interpretation of the time evolution process, and a crossover to ordinary exponential statistics are given. We make clear the dynamical origin of the anomalous thermodynamic framework existing at the Feigenbaum attractor.

  7. Effect of Radial and Axial Deformation on Electron Transport Properties in a Semiconducting Si-C Nanotube

    S. Choudhary

    2011-01-01

    Full Text Available We study the bias voltage dependent current characteristic in a deformed (8, 0 silicon carbide nanotube by applying self consistent non-equilibrium Greens function formalism in combination with the density-functional theory to a two probe molecular junction constructed from deformed nanotube. The transmission spectra and electron density of states at zero bias shows a significant reduction in threshold in the case of both radially compressed and axially elongated nanotube. However, semiconductor to metal transition was not observed, though the results show large differences in current characteristic compared to a perfect nanotube.

  8. Decay of quadrupole-octupole 1- states in 40Ca and 140Ce

    Derya, V.; Tsoneva, N.; Aumann, T.; Bhike, M.; Endres, J.; Gooden, M.; Hennig, A.; Isaak, J.; Lenske, H.; Löher, B.; Pietralla, N.; Savran, D.; Tornow, W.; Werner, V.; Zilges, A.

    2016-03-01

    Background: Two-phonon excitations originating from the coupling of two collective one-phonon states are of great interest in nuclear structure physics. One possibility to generate low-lying E 1 excitations is the coupling of quadrupole and octupole phonons. Purpose: In this work, the γ -decay behavior of candidates for the (21+⊗31-)1- state in the doubly magic nucleus 40Ca and in the heavier and semimagic nucleus 140Ce is investigated. Methods: (γ ⃗,γ') experiments have been carried out at the High Intensity γ -ray Source (HI γ S ) facility in combination with the high-efficiency γ -ray spectroscopy setup γ3 consisting of HPGe and LaBr3 detectors. The setup enables the acquisition of γ -γ coincidence data and, hence, the detection of direct decay paths. Results: In addition to the known ground-state decays, for 40Ca the decay into the 31- state was observed, while for 140Ce the direct decays into the 21+ and the 02+ state were detected. The experimentally deduced transition strengths and excitation energies are compared to theoretical calculations in the framework of EDF theory plus QPM approach and systematically analyzed for N =82 isotones. In addition, negative parities for two J =1 states in 44Ca were deduced simultaneously. Conclusions: The experimental findings together with the theoretical calculations support the two-phonon character of the 11- excitation in the light-to-medium-mass nucleus 40Ca as well as in the stable even-even N =82 nuclei.

  9. Is nucleon deformed?

    The surprising answer to this question Is nucleon deformed? is : Yes. The evidence comes from a study of the quark model of the single nucleon and when it is found in a nucleus. It turns out that many of the long standing problems of the Naive Quark Model are taken care of if the nucleon is assumed to be deformed. Only one value of the parameter PD ?1/4 (which specifies deformation) fits gA (the axial vector coupling constant) for all the semileptonic decay of baryons, the F/D ratio, the pion-nucleon-delta coupling constant fsub(?N?), the double delta coupling constant1 fsub(???), the Ml transition moment ??N and g1p the spin structure function of proton2. All this gives strong hint that both neutron and proton are deformed. It is important to look for further signatures of this deformation. When this deformed nucleon finds itself in a nuclear medium its deformation decreases. So much that in a heavy nucleus the nucleons are actually spherical. We look into the Gamow-Teller strengths, magnetic moments and magnetic transition strengths in nuclei to study this property. (author). 15 refs

  10. Effect of annealing and biaxial deformation on the dielectric properties of composites of multiwall carbon nanotubes and poly(ethylene terephthalate)

    Urvakis, Marius; Kupreviciute, Auste; Banys, Juras; Macutkevic, Jan; Mayoral, Beatriz; McNally, Tony

    2012-01-01

    The dielectric properties of composites of poly(ethylene terephthalate) (PET) with MWCNTs were investigated over a wide frequency and temperature range below and close to the electrical percolation threshold. In composites with 1 wt.% multiwall carbon nanotubes (MWCNT) inclusions, the dielectric properties below room temperature are mostly determined by β relaxation, as a consequence of the rotation of PET molecules. In stretched samples, the CNTs are oriented at about 45 deg to the stretch direction. Such deformation increased the potential for molecular rotation. However, annealing after stretching increased homogeneity of the composite and decreased the potential barrier for polymer chain rotation. Electrical conductivity effects and Maxwell-Wagner polarization mostly cause the dielectric properties of the samples with 2% MWCNT inclusions. The potential barrier for carrier tunneling is lowest in the annealed sample.

  11. Mechanical properties of Fe -10Ni -7Mn martensitic steel subjected to severe plastic deformation via cold rolling and wire drawing

    Ghasemi-Nanesa, H; Shirazi, H [School of Metallurgy and Materials Engineering, Faculty of Engineering, University of Tehran, P.O. Box 14395-731 (Iran, Islamic Republic of); Nili-Ahmadabadi, M, E-mail: sut.caster.81710018@gmail.co, E-mail: nili@ut.ac.i [School of Metallurgy and Materials Engineering, Faculty of Engineering, University of Tehran, P.O. Box 14395-731 (Iran, Islamic Republic of) and Center of Excellence for High Performance Materials, University of Tehran, P.O. Box 14395-731, Tehran (Iran, Islamic Republic of)

    2010-07-01

    Fe-Ni-Mn martensitic steels are one of the major groups of ultra-high strength steels that have good mechanical properties and ductility in as annealed condition but they suffer from severe inter-granular embitterment after aging. In this paper, the effect of heavy shaped cold rolling and wire drawing on the mechanical properties of Fe-Ni-Mn steel was investigated. This process could provide a large strain deformation in this alloy. The total strain was {epsilon} {approx}7. Aging behavior and tensile properties of Fe-10Ni-7Mn were studied after aging at 753 K. The results showed that the ultimate tensile strength and ductility after cold rolling, wire drawing and aging increased up to 2540 MPa and 7.1 %, respectively, while the conventional steels show a premature fracture stress of 830 MPa with about zero ductility after aging.

  12. Mechanical properties of Fe -10Ni -7Mn martensitic steel subjected to severe plastic deformation via cold rolling and wire drawing

    Fe-Ni-Mn martensitic steels are one of the major groups of ultra-high strength steels that have good mechanical properties and ductility in as annealed condition but they suffer from severe inter-granular embitterment after aging. In this paper, the effect of heavy shaped cold rolling and wire drawing on the mechanical properties of Fe-Ni-Mn steel was investigated. This process could provide a large strain deformation in this alloy. The total strain was ε ∼7. Aging behavior and tensile properties of Fe-10Ni-7Mn were studied after aging at 753 K. The results showed that the ultimate tensile strength and ductility after cold rolling, wire drawing and aging increased up to 2540 MPa and 7.1 %, respectively, while the conventional steels show a premature fracture stress of 830 MPa with about zero ductility after aging.

  13. A Comparison of Two Magnetic Ultra-Cold Neutron Trapping Concepts Using a Halbach-Octupole Array

    Leung, K.; Ivanov, S.; Martin, F.; Rosenau, F.; Simson, M.; Zimmer, O.

    2014-03-01

    This paper describes a new magnetic trap for ultra-cold neutrons (UCNs) made from a 1.2m long Halbach-octupole array of permanent magnets with an inner bore radius of 47mm combined with an assembly of superconducting end coils and bias field solenoid. The use of the trap in a vertical, magneto-gravitational and a horizontal setup are compared in terms of the effective volume and ability to control key systematic effects that need to be addressed in high precision neutron lifetime measurements.

  14. Measurements of octupole collectivity in $^{220,222}$Rn and $^{222,224}$Ra using Coulomb excitation

    Kruecken, R; Larsen, A; Hurst, A M; Voulot, D; Grahn, T; Clement, E; Wadsworth, R; Gernhaeuser, R A; Siem, S; Van duppen, P L E; Page, R; Barton, C J; Wenander, F J C; Huyse, M L; Iwanicki, J S; Warr, N V

    2008-01-01

    We propose to exploit the unique capability of ISOLDE to provide post-accelerated $^{220,222}$Rn and $^{222,224}$Ra ion beams from the REX facility to enable the Coulomb excitation of the first 3$^{-}$ states in these nuclei. By measuring the $\\gamma$-ray yields of the E1 decays from the 3$^{-}$ state using the MINIBALL array we can obtain the transition matrix elements. This will give quantitative information about octupole correlations in these nuclei. We require 22 shifts to fulfil the aims of the experiment.

  15. Interference between selected dipoles and octupoles in the optical second-harmonic generation from spherical gold nanoparticles.

    Butet, J; Bachelier, G; Russier-Antoine, I; Jonin, C; Benichou, E; Brevet, P-F

    2010-08-13

    Optical second-harmonic generation from gold nanoparticles is investigated both experimentally and theoretically. The contribution of octupoles is reported for the first time in the second-harmonic emission pattern, by using an harmonic polarization in the scattering plane. The experimental results presented here for particle sizes up to 100nm are in excellent agreement with finite element method simulations involving the normal surface term only in the nonlinear polarization source. In addition, analytical calculations based on nonlinear Mie scattering theory clearly evidence the constructive and destructive interferences occurring between the dipolar and octupolar responses selected with this polarization configuration. PMID:20868074

  16. A comparison of two magnetic ultra-cold neutron trapping concepts using a Halbach-octupole array

    Leung, K; Martin, F; Rosenau, F; Simson, M; Zimmer, O

    2015-01-01

    This paper describes a new magnetic trap for ultra-cold neutrons (UCNs) made from a 1.2 m long Halbach-octupole array of permanent magnets with an inner bore radius of 47 mm combined with an assembly of superconducting end coils and bias field solenoid. The use of the trap in a vertical, magneto-gravitational and a horizontal setup are compared in terms of the effective volume and ability to control key systematic effects that need to be addressed in high precision neutron lifetime measurements.

  17. Nanomechanical Properties and Deformation Behaviors of Multi-Component (AlCrTaTiZrNxSiy High-Entropy Coatings

    Shao-Yi Lin

    2013-12-01

    Full Text Available In this study multi-component (AlCrTaTiZrNxSiy high-entropy coatings were developed by co-sputtering of AlCrTaTiZr alloy and Si in an Ar/N2 mixed atmosphere with the application of different substrate biases and Si-target powers. Their nanomechanical properties and deformation behaviors were characterized by nanoindentation tests. Because of the effect of high mixing entropies, all the deposited multi-component (AlCrTaTiZrNxSiy high-entropy coatings exhibited a simple face-centered cubic solid-solution structure. With an increased substrate bias and Si-target power, their microstructures changed from large columns with a [111] preferred orientation to a nanocomposite form with ultrafine grains. The hardness, H/E ratio and H3/E2 ratio of (AlCrTaTiZrN1.07Si0.15 coating reached 30.2 GPa, 0.12 and 0.41 GPa, respectively, suggesting markedly suppressed dislocation activities and a very high resistance to wear and plastic deformation, attributable to grain refinements and film densification by the application of substrate bias, a nanocomposite structure by the introduction of silicon nitrides, and a strengthening effect induced by severe lattice distortions. In the deformed regions under indents, stacking faults or partial dislocations were formed, while in the stress-released regions, near-perfect lattices recovered.

  18. Elastic Deformations in 2D van der waals Heterostructures and their Impact on Optoelectronic Properties: Predictions from a Multiscale Computational Approach

    Kumar, Hemant; Er, Dequan; Dong, Liang; Li, Junwen; Shenoy, Vivek B.

    2015-06-01

    Recent technological advances in the isolation and transfer of different 2-dimensional (2D) materials have led to renewed interest in stacked Van der Waals (vdW) heterostructures. Interlayer interactions and lattice mismatch between two different monolayers cause elastic strains, which significantly affects their electronic properties. Using a multiscale computational method, we demonstrate that significant in-plane strains and the out-of-plane displacements are introduced in three different bilayer structures, namely graphene-hBN, MoS2-WS2 and MoSe2-WSe2, due to interlayer interactions which can cause bandgap change of up to ~300 meV. Furthermore, the magnitude of the elastic deformations can be controlled by changing the relative rotation angle between two layers. Magnitude of the out-of-plane displacements in graphene agrees well with those observed in experiments and can explain the experimentally observed bandgap opening in graphene. Upon increasing the relative rotation angle between the two lattices from 0° to 10°, the magnitude of the out-of-plane displacements decrease while in-plane strains peaks when the angle is ~6°. For large misorientation angles (>10°), the out-of-plane displacements become negligible. We further predict the deformation fields for MoS2-WS2 and MoSe2-WSe2 heterostructures that have been recently synthesized experimentally and estimate the effect of these deformation fields on near-gap states.

  19. Deformation mechanisms, architecture, and petrophysical properties of large normal faults in platform carbonates and their role in the release of carbon dioxide from earth's interior in central Italy

    Agosta, Fabrizio

    2006-04-01

    A challenging theme of research in structural geology is the process of faulting in carbonate rocks: how do the resulting internal architecture and petrophysical properties of faults affect subsurface fluid flow. A better understanding of this process is important to evaluate the potential oil and gas recovery from carbonate reservoirs, and to plan CO 2 containment in the depleted reservoirs. Carbonate rocks may deform with different mechanisms depending primarily on their original sedimentary fabric, diagenetic history, fluid content, and tectonic environment. In this dissertation I investigate the deformation mechanisms, petrophysics, and internal fluid composition of large, seismic, basin-bounding normal faults in low porosity platform carbonates. Based on the nature, orientation, and abutting relationships of the structural elements preserved within the faults and in the surrounding carbonate host rocks, I was able to characterize the mechanisms of fault growth and the fault architecture. Incipient faulting occurred at shallow depths by sequential formation and shearing of pressure solution seams and joints/veins; with ongoing deformation and exhumation, the joint-based mechanism became predominant. The end result is a mature normal fault that juxtaposes basin sedimentary rocks of the hanging wall against deformed carbonates of the footwall. The deformed carbonates of the fault footwalls are composed of rocks with low porosity and permeability and major slip surfaces in the fault core, and fragmented carbonate matrices with high porosity and permeability, and small faults in the damage zone. The degree of fragmentation in the damage zone generally increases towards the fault hanging wall, forming structural domains characterized by different deformation intensity. The rocks of the fault core have sub-spherical pores, those of the damage zone have elongated, crack-like, pores. The permeability structure of the normal fault zones is therefore made up of a fault core that acts as a barrier to fluid flow, and fragmented carbonates that enhance fluid flow. Stable isotope geochemistry data shows two main sources of the fluids that precipitated minerals within the normal faults. The main fluid source is infiltrated meteoric water, the second is CO2-enriched groundwater. Both fluids compartmentalized primarily along the major slip surfaces of the fault cores.

  20. Influency of ordered phase precipitation on mechanical properties and deformation character of single crystals of ageing Ni-14.4 at. % Mo alloy

    Investigated were the particularities of the ageing Ni-14.4 at.% Mo alloy structure, formed in the course of an isothermal annealing at 700 deg C. The effect of the precipitation of the NiMo ordered phase upon the strength properties of alloy single-crystals has been studied. The character of the dislocation structure of variously treated alloys on various stages of deformation has been studied. The conditions of the transition of the preferable slipping from the primary system to the associated system have been deermined and a conclusion has been drawn that this transition is caused by the attainment of the ''limit'' level of strengthening in the primary system

  1. q-Deformed Statistical-Mechanical Property in the Dynamics of Trajectories en route to the Feigenbaum Attractor

    Robledo, A.; Moyano, L. G.

    2008-01-01

    We demonstrate that the dynamics towards and within the Feigenbaum attractor combine to form a q-deformed statistical-mechanical construction. The rate at which ensemble trajectories converge to the attractor (and to the repellor) is described by a q-entropy obtained from a partition function generated by summing distances between neighboring positions of the attractor. The values of the q-indices involved are given by the unimodal map universal constants, while the thermodynamic structure is...

  2. Deformation and properties of ribbons of amorphous FeCo80-xSi15Bx alloys

    Change in morphology of shear bands, propagation of micro- and macrocracks, structure as well as coercive force Hc of rolled strips of Fe5Co80-xSi15Bx amorphous alloys, is studied, where x has the following values: 8.2; 10; 11.8 at.%. The found essential (more than 200 times) increase of Hc after deformation is explained by appearance of internal stresses, microcracks and nuclei of crystal phase

  3. One-particle properties of deformed N $\\approx$ 28 odd-N nuclei with weakly-bound or resonant neutrons

    Hamamoto, Ikuko

    2008-01-01

    Possible deformation of odd-N nuclei with N $\\approx$ 28 towards the neutron drip line is investigated using the Nilsson diagram based on deformed Woods-Saxon potentials. Both weakly-bound and resonant one-particle levels are properly obtained by directly solving the Schr\\"{o}dinger equation in mesh of space coordinate with the correct boundary condition. If we use the same diffuseness of the potential as that of $\\beta$-stable nuclei, the energy difference between the neutron 2p$_{3/2}$ and 1f$_{7/2}$ levels becomes very small or the N=28 energy gap almost disappears, as the binding energies of those levels approach zero. This suggests that the ground states of those neutron drip line nuclei are likely to be deformed. In particular, the spin-parity and the magnetic moment of the ground state of odd-N nuclei, $^{43}_{16}$S$_{27}$ and $^{45}_{16}$S$_{29}$, are examined. Moreover, it is suggested that in $^{39}_{12}$Mg$_{27}$ lying outside the drip line the lowest resonant state may have 5/2$^{-}$, if the N=28 ...

  4. q-Deformed Dynamics and Virial Theorem

    Zhang, Jian-zu

    2002-01-01

    In the framework of the q-deformed Heisenberg algebra the investigation of $q$-deformation of Virial theorem explores that q-deformed quantum mechanics possesses better dynamical property. It is clarified that in the case of the zero potential the theoretical framework for the q-deformed Virial theorem is self-consistent. In the selfadjoint states the q-deformed uncertainty relation essentially deviates from the Heisenberg one.

  5. On the nature of low-lying electric dipole excitations in light and heavy deformed nuclei

    Guhr, T.; Hummel, K.D.; Kilgus, G.; Bohle, D.; Richter, A. (Technische Hochschule Darmstadt (Germany, F.R.). Inst. fuer Kernphysik); Jager, C.W. de; Vries, H. de; Witt Huberts, P.K.A. de (Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands). Sectie K)

    1989-09-11

    Form factors from high-resolution inelastic electron scattering on {sup 48}Ti, {sup 164}Dy, {sup 232}Th and {sup 238}U display the fact that the E1 transition to the lowest lying J{sup {pi}} = 1{sup -} states is excited by the same mode in light and heavy nuclei. A description of the form factor in terms of surface octupole vibrations of the nucleus around a quadrupole deformed shape is shape shown to work quite well up to its second maximum. The E1 strength found at the photon point is explained satisfactorily by taking into account the mixing with the electric giant dipole resonance. (orig.).

  6. Anyons and Deformed Lie Algebras

    Frau, Marialuisa; Lerda, Alberto; Sciuto, Stefano

    1994-01-01

    We discuss the connection between anyons (particles with fractional statistics) and deformed Lie algebras (quantum groups). After a brief review of the main properties of anyons, we present the details of the anyonic realization of all deformed classical Lie algebras in terms of anyonic oscillators. The deformation parameter of the quantum groups is directly related to the statistics parameter of the anyons. Such a realization is a direct generalization of the Schwinger construction in terms ...

  7. Basic-deformed quantum mechanics

    Lavagno, A

    2009-01-01

    Starting on the basis of $q$-symmetric oscillator algebra and on the associate $q$-calculus properties, we study a deformed quantum mechanics defined in the framework of the basic square-integrable wave functions space. In this context, we introduce a deformed Schroedinger equation, which satisfies the main quantum mechanics assumptions and admits, in the free case, plane wave functions that can be expressed in terms of the q-deformed exponential, originally introduced in the framework of the...

  8. Experimental Study of the Bending Properties and Deformation Analysis of Web-Reinforced Composite Sandwich Floor Slabs with Four Simply Supported Edges.

    Qi, Yujun; Fang, Hai; Liu, Weiqing

    2016-01-01

    Web-reinforced composite sandwich panels exhibit good mechanical properties in one-way bending, but few studies have investigated their flexural behavior and deformation calculation methods under conditions of four simply supported edges. This paper studies the bending performance of and deformation calculation methods for two-way web-reinforced composite sandwich panels with different web spacing and heights. Polyurethane foam, two-way orthogonal glass-fiber woven cloth and unsaturated resin were used as raw materials in this study. Vacuum infusion molding was used to prepare an ordinary composite sandwich panel and 5 web-reinforced composite sandwich panels with different spacing and web heights. The panels were subjected to two-way panel bending tests with simple support for all four edges. The mechanical properties of these sandwich panels during the elastic stage were determined by applying uniformly distributed loads. The non-linear mechanical characteristics and failure modes were obtained under centrally concentrated loading. Finally, simulations of the sandwich panels, which used the mechanical model established herein, were used to deduce the formulae for the deflection deformation for this type of sandwich panel. The experimental results show that webs can significantly improve the limit bearing capacity and flexural rigidity of sandwich panels, with smaller web spacing producing a stronger effect. When the web spacing is 75 mm, the limit bearing capacity is 4.63 times that of an ordinary sandwich panel. The deduced deflection calculation formulae provide values that agree well with the measurements (maximum error <15%). The results that are obtained herein can provide a foundation for the structural design of this type of panel. PMID:26871435

  9. Experimental Study of the Bending Properties and Deformation Analysis of Web-Reinforced Composite Sandwich Floor Slabs with Four Simply Supported Edges

    Qi, Yujun; Fang, Hai; Liu, Weiqing

    2016-01-01

    Web-reinforced composite sandwich panels exhibit good mechanical properties in one-way bending, but few studies have investigated their flexural behavior and deformation calculation methods under conditions of four simply supported edges. This paper studies the bending performance of and deformation calculation methods for two-way web-reinforced composite sandwich panels with different web spacing and heights. Polyurethane foam, two-way orthogonal glass-fiber woven cloth and unsaturated resin were used as raw materials in this study. Vacuum infusion molding was used to prepare an ordinary composite sandwich panel and 5 web-reinforced composite sandwich panels with different spacing and web heights. The panels were subjected to two-way panel bending tests with simple support for all four edges. The mechanical properties of these sandwich panels during the elastic stage were determined by applying uniformly distributed loads. The non-linear mechanical characteristics and failure modes were obtained under centrally concentrated loading. Finally, simulations of the sandwich panels, which used the mechanical model established herein, were used to deduce the formulae for the deflection deformation for this type of sandwich panel. The experimental results show that webs can significantly improve the limit bearing capacity and flexural rigidity of sandwich panels, with smaller web spacing producing a stronger effect. When the web spacing is 75 mm, the limit bearing capacity is 4.63 times that of an ordinary sandwich panel. The deduced deflection calculation formulae provide values that agree well with the measurements (maximum error <15%). The results that are obtained herein can provide a foundation for the structural design of this type of panel. PMID:26871435

  10. Proposal for the award of a contract for the supply of superconducting octupole corrector magnets for the LHC

    2000-01-01

    This document concerns the award of a contract for the supply of 168 MO superconducting octupole corrector magnet assemblies for the LHC. Following a market survey (MS-2594/LHC/LHC) carried out among 39 firms in thirteen Member States, two firms in Japan and one firm in the USA, a call for tenders (IT-2595/LHC/LHC) was sent on 15 February 2000 to 11 firms in seven Member States. By the closing date, CERN had received seven tenders. The Finance Committee is invited to agree to the negotiation of a contract with the firm ANTEC (ES), the lowest bidder, for the supply of 168 MO superconducting octupole corrector magnet assemblies for the LHC for a total amount of 2 075 935 Swiss francs, subject to revision for contractual deliveries after 31 December 2001, with an option for the supply of up to 50 additional MO corrector magnet assemblies, for a total amount of 526 400 Swiss francs, subject to revision for contractual deliveries after 31 December 2001, bringing the total amount to a maximum of 2 602 335 Swiss fra...

  11. Evolution of quadrupole and octupole collectivity north-east of $^{132}$ Sn: the event Te and Xe isotopes

    We propose to study excited states in isotopes north-east of the doubly-magic $^{132}$Sn by $\\gamma$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to the determine B(E2) and B(E3) values to follow the evolution of quadrupole and octupole collectivity when going away from the shell closures at Z = 50 and N = 82. The B(E2; 0$^+_{gs}$ $\\rightarrow$ 2$^+_{1}$) values in the even isotopes $^{138-144}$Xe have been measured at REX-ISOLDE and the systematic trend towards neutron-rich nuclei is well described even by an empirical Grodzins-type formula. An increasing dipole moment observed for $^{140;142}$Xe is interpreted as indirect signature of increasing octupole correlations peaking at N = 88. So far, no B(E3) values are known. In contrast to the Xe isotopes, the Te ones, in particular $^{136}$Te, are known for their notoriously irregular behaviour. In order to understand the nuclear structure also on a microscopic basis, the isotope $^{136}$Te with just one pair of protons and neutrons...

  12. Effect of Deformation and Aging on Properties of Al-4.1%Cu-1.4%Mg Aluminum Alloy

    Wang, Hao; Li, Changsheng; Li, Jing; Wei, Xinglong; Mei, Ruibin

    2013-01-01

    Deformation scheme and preheat treatment of Al-4.1%Cu-1.4%Mg aluminum alloy are chosen, homogenizing annealing at 430C for 1.5?h, cooling to 250C in furnace at a cooling rate of less than 30C/h and then cooling to room temperature to make Al-4.1%Cu-1.4%Mg aluminum alloy annealed fully. Heat treatment tests of Al-4.1%Cu-1.4%Mg aluminum alloy mainly consisting of rolling and aging were conducted, and the optimum peak of aging mechanism is 190C/12?h. Through comparison of microstructure and ...

  13. Mechanical properties and peculiar features of energy dissipation of ultrafine-grained aluminum alloys under dynamic deformation

    Petrova, A.; Brodova, I.; Shorokhov, E.; Plekhov, O.; Naimark, O.

    2014-08-01

    This paper presents experimental results on the thermodynamics of deformation process and mechanical behavior of the ultrafine grained aluminum alloys under dynamic compression. Dynamic compression tests were performed on a Hopkinson-Kolsky split bar at the strain rate of 103 s'1 with simultaneously recording the surface temperature of samples by an infrared camera. Energy dissipation ability was determined for ultrafine-grained alloys. An inverse strain rate dependency of dynamic yield strength was observed in the ultrafine-grained Al-Zn-Mg-Cu alloy (A7075).

  14. Deformed shell model studies of spectroscopic properties of 64Zn and 64Ni and the positron double beta decay of 64Zn

    R Sahu; V K B Kota

    2014-04-01

    The spectroscopic properties of 64Zn and 64Ni are calculated within the framework of the deformed shell model (DSM) based on Hartree–Fock states. GXPF1A interaction in 1 $f_{7/2}$, 2$p_{3/2}$, 1$f_{5/2}$ and 2$p_{1/2}$ space with 40Ca as the core is employed. After ensuring that DSM gives good description of the spectroscopic properties of low-lying levels in these two nuclei considered, nuclear transition matrix elements (NTME) for the neutrinoless positron double beta decay (0 + and 0 +EC) of 64Zn are calculated. The two-neutrino positron double beta decay halflife is also calculated for this nucleus.

  15. Deformation and electrical properties of magnetic and vertically conductive composites with a chain-of-spheres structure

    Choi, Chulmin; Hong, Soonkook; Chen, Li-Han; Liu, Chin-Hung; Choi, Duyoung; Kuru, Cihan; Jin, Sungho

    2014-05-01

    Vertically anisotropically conductive composites with aligned chain-of-spheres of 20-75 mm Ni particles in an elastomer matrix have been prepared by curing the mixture at 100°C-150°C under an applied magnetic field of ˜300-1000 Oe. The particles are coated with a ˜120 nm thick Au layer for enhanced electrical conductivity. The resultant vertically aligned but laterally isolated columns of conductive particles extend through the whole composite thickness and the end of the Ni columns protrude from the surface, contributing to enhanced electrical contact on the composite surface. The stress-strain curve on compressive deformation exhibits a nonlinear behavior with a rapidly increasing Young's modulus with stress (or pressure). The electrical contact resistance Rc decreases rapidly when the applied pressure is small and then more gradually after the applied pressure reaches 500 psi (˜3.4 MPa), corresponding to a 30% deformation. The directionally conductive elastomer composite material with metal pads and conductive electrodes on the substrate surface can be used as a convenient tactile shear sensor for applications involving artificial limbs, robotic devices, and other visual communication devices such as touch sensitive screens.

  16. Quantifying the Mechanical Properties of Materials and the Process of Elastic-Plastic Deformation under External Stress on Material

    Jan Valíček

    2015-11-01

    Full Text Available The paper solves the problem of the nonexistence of a new method for calculation of dynamics of stress-deformation states of deformation tool-material systems including the construction of stress-strain diagrams. The presented solution focuses on explaining the mechanical behavior of materials after cutting by abrasive waterjet technology (AWJ, especially from the point of view of generated surface topography. AWJ is a flexible tool accurately responding to the mechanical resistance of the material according to the accurately determined shape and roughness of machined surfaces. From the surface topography, it is possible to resolve the transition from ideally elastic to quasi-elastic and plastic stress-strain states. For detecting the surface structure, an optical profilometer was used. Based on the analysis of experimental measurements and the results of analytical studies, a mathematical-physical model was created and an exact method of acquiring the equivalents of mechanical parameters from the topography of surfaces generated by abrasive waterjet cutting and external stress in general was determined. The results of the new approach to the construction of stress-strain diagrams are presented. The calculated values agreed very well with those obtained by a certified laboratory VÚHŽ.

  17. Isoscalar octupole transition rates in 50Ti, 52Cr and 208Pb from model-independent analyses of 104 MeV ?-particle scattering

    Applying a recently proposed method for model-independent analyses experimental differential cross sections for 104 MeV ?-particle scattering have been analyzed. Reliable values of isoscalar (0+-3-1) octupole transition rates in 50Ti, 52Cr and 208 Pb are presented and compared with electromagnetic rates. (orig.)

  18. Multipole modes in deformed nuclei within the finite amplitude method

    Kortelainen, M.; Hinohara, N.; Nazarewicz, W.

    2015-11-01

    Background: To access selected excited states of nuclei, within the framework of nuclear density functional theory, the quasiparticle random phase approximation (QRPA) is commonly used. Purpose: We present a computationally efficient, fully self-consistent framework to compute the QRPA transition strength function of an arbitrary multipole operator in axially deformed superfluid nuclei. Methods: The method is based on the finite amplitude method (FAM) QRPA, allowing fast iterative solution of QRPA equations. A numerical implementation of the FAM-QRPA solver module has been carried out for deformed nuclei. Results: The practical feasibility of the deformed FAM module has been demonstrated. In particular, we calculate the quadrupole and octupole strengths in a heavy deformed nucleus 240Pu, without any truncations in the quasiparticle space. To demonstrate the capability to calculate individual QRPA modes, we also compute low-lying negative-parity collective states in 154Sm. Conclusions: The new FAM implementation enables calculations of the QRPA strength function throughout the nuclear landscape. This will facilitate global surveys of multipole modes and ? decays and will open new avenues for constraining the nuclear energy density functional.

  19. Influence of Partitioning Process on the Microstructure and Mechanical Properties of High Deformability Oil-Gas Pipeline

    Ma, Jing; Zhang, Xiaoyong; Cheng, Shixia; Gao, Huilin

    2014-01-01

    Multiphase structure of bainite and M/A constituent can be obtained for X80 oil-gas pipeline through a novel heat online partitioning (HOP) technology. The effects of partitioning temperature on the microstructure and mechanical properties of the experimental steels were researched by means of mechanical properties test, microscopic analysis, and X-ray diffraction. The results show that with the increase of the partitioning temperature, the strength of the experimental steel decreases and the...

  20. An investigation to the effect of deformation-heat treatment cycle on the eutectic morphology and mechanical properties of a Thixocast A356 alloy

    Haghshenas, M., E-mail: mhaghshe@uwo.ca [School of Metallurgical and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Zarei-Hanzaki, A. [School of Metallurgical and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Jahazi, M. [Aerospace Manufacturing Technology Centre, Institute for Aerospace Research, National Research Council Canada, 5145 Decelles Avenue, Montreal, Quebec, H3T 2B2 (Canada)

    2009-08-15

    The influences of deformation, heat treatment temperature and holding time on morphology and size distribution of Si containing eutectic phases of Thixocast Al-7Si-0.4 Mg alloy were investigated. The novel thermo-mechanical treatment consisted of initial cold working practice followed by a solution heat treatment at 540 deg. C for durations ranging from 2 min to 120 min followed by water quenching. Optical and scanning electron microscopes were used to study the influence of process parameters on microstructure evolution. Also, final mechanical properties were investigated using hardness test. The results indicate that, under appropriate conditions it is possible to achieve an ultrafine grain microstructure with the eutectic Si fibers fragmented and spheroidized in the entire microstructure. It was also found that, an agglomeration of sphrodized particles occurs and is governed by Ostwald ripening mechanism.

  1. An investigation to the effect of deformation-heat treatment cycle on the eutectic morphology and mechanical properties of a Thixocast A356 alloy

    The influences of deformation, heat treatment temperature and holding time on morphology and size distribution of Si containing eutectic phases of Thixocast Al-7Si-0.4 Mg alloy were investigated. The novel thermo-mechanical treatment consisted of initial cold working practice followed by a solution heat treatment at 540 deg. C for durations ranging from 2 min to 120 min followed by water quenching. Optical and scanning electron microscopes were used to study the influence of process parameters on microstructure evolution. Also, final mechanical properties were investigated using hardness test. The results indicate that, under appropriate conditions it is possible to achieve an ultrafine grain microstructure with the eutectic Si fibers fragmented and spheroidized in the entire microstructure. It was also found that, an agglomeration of sphrodized particles occurs and is governed by Ostwald ripening mechanism.

  2. Ti-O/TiN films synthesized by plasma immersion ion implantation and deposition on 316L: Study of deformation behavior and mechanical properties

    Ti-O/TiN gradient films have been synthesized on 316L stainless steel using plasma immersion ion implantation and deposition (PIII and D). The coated samples were subjected to tensile testing and observed in situ by scanning electron microscopy. No delamination, peeling or cracking was found on the film after plastic deformation of 0.16 mm residual displacement. Nanoindentation and nanoscratch tests revealed that the prepared films possess high nanohardness and good adhesion strength to the metal substrate. The mechanical properties of the synthesized Ti-O/TiN films are thought to be attributed to the good nanostructure, high density, smooth surface, slow transition from Ti-O to TiN and broad film/matrix interface achieved by the PIII-D process

  3. Ti-O/TiN films synthesized by plasma immersion ion implantation and deposition on 316L: Study of deformation behavior and mechanical properties

    Wan, G.J. [Key Lab. of Biomaterials Surface Modification of Sichuan, Key Lab. of Advanced Materials Processing of Chinese Education Ministry, College of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031 (China)]. E-mail: biomat@biomatchina.com; Huang, N. [Key Lab. of Biomaterials Surface Modification of Sichuan, Key Lab. of Advanced Materials Processing of Chinese Education Ministry, College of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031 (China); Yang, P. [Key Lab. of Biomaterials Surface Modification of Sichuan, Key Lab. of Advanced Materials Processing of Chinese Education Ministry, College of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031 (China); Leng, Y.X. [Key Lab. of Biomaterials Surface Modification of Sichuan, Key Lab. of Advanced Materials Processing of Chinese Education Ministry, College of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031 (China); Sun, H. [Key Lab. of Biomaterials Surface Modification of Sichuan, Key Lab. of Advanced Materials Processing of Chinese Education Ministry, College of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031 (China); Chen, J.Y. [Key Lab. of Biomaterials Surface Modification of Sichuan, Key Lab. of Advanced Materials Processing of Chinese Education Ministry, College of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031 (China); Wang, J. [Key Lab. of Biomaterials Surface Modification of Sichuan, Key Lab. of Advanced Materials Processing of Chinese Education Ministry, College of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031 (China)

    2005-07-22

    Ti-O/TiN gradient films have been synthesized on 316L stainless steel using plasma immersion ion implantation and deposition (PIII and D). The coated samples were subjected to tensile testing and observed in situ by scanning electron microscopy. No delamination, peeling or cracking was found on the film after plastic deformation of 0.16 mm residual displacement. Nanoindentation and nanoscratch tests revealed that the prepared films possess high nanohardness and good adhesion strength to the metal substrate. The mechanical properties of the synthesized Ti-O/TiN films are thought to be attributed to the good nanostructure, high density, smooth surface, slow transition from Ti-O to TiN and broad film/matrix interface achieved by the PIII-D process.

  4. Deformation microstructures

    Hansen, N.; Huang, X.; Hughes, D.A.

    Microstructural characterization and modeling has shown that a variety of metals deformed by different thermomechanical processes follows a general path of grain subdivision, by dislocation boundaries and high angle boundaries. This subdivision has been observed to very small structural scales of...

  5. Alternating parity bands in doubly odd 218Ac129 and octupole instability in the light actinide region

    High-spin states of doubly odd 218Ac129 have been investigated using in-beam α, γ and conversion electron spectroscopy techniques through the 209Bi(12(13)C,3(4)n) fusion-evaporation reactions. The level scheme of 218Ac shows three interconnected, alternating parity structures, each one linked by strong E1 transitions. Two of these bands are strikingly similar to the known scheme of the isotone 217Ra and this analogy is shown to persist for the pair 220Ac, 219Ra. The relation between the structure of 218Ac and its neighbors is thoroughly discussed showing that the first signals of octupole collectivity appear for N = 129. (orig.)

  6. New high-spin states of {sup 147}Nd and {sup 145}Ce: Octupole correlation in the N=87 isotones

    Venkova, Ts.; Petkov, P. [Univ. Paris-Sud, Orsay (France). CNRS; Bulgarian Academy of Sciences, Sofia (Bulgaria). Inst. of Nuclear Research; Porquet, M.-G.; Astier, A.; Deloncle, I.; Prevost, A. [IN2P3-CNRS/Universite Paris-Sud, CSNSM, Orsay (France); Azaiez, F.; Buta, A.; Curien, D.; Dorvaux, O.; Duchene, G.; Gall, B.J.P.; Khalfallah, F.; Piqueras, I.; Rousseau, M. [IN2P3-CNRS/Universite Louis Pasteur, IReS, Strasbourg Cedex 2 (France); Bogachev, A. [JINR, Dubna, Moscow region (Russian Federation); Durell, J.; Roach, A. [University of Manchester, Department of Physics and Astronomy, Manchester (United Kingdom); Houry, M.; Lucas, R.; Theisen, Ch. [CEA/DSM/DAPNIA/SPhN, Commissariat a l' Energie Atomique, Gif-sur-Yvette Cedex (France); Meyer, M.; Redon, N.; Stezowski, O. [IN2P3-CNRS/Universite Claude Bernard, IPNL, Villeurbanne Cedex (France)

    2005-12-01

    High-spin states of the N=87 nuclei, {sup 147}Nd and {sup 145}Ce, have been populated in the {sup 12}C+{sup 238}U and {sup 18}O+{sup 208}Pb fusion-fission reactions at 90 MeV and 85 MeV bombarding energy, respectively. The emitted {gamma}-radiation was detected using the Euroball III and IV arrays. High-spin states of the {sup 147}Nd isotope have been identified for the first time. The high-spin yrast and near-to-yrast structures of the {sup 145}Ce nucleus have been considerably extended. The newly observed structures, discussed by analogy with the neighbouring isotones, show the coupling of an h{sub 9/2} neutron to the quadrupole and octupole excitations of the core. (orig.)

  7. New high-spin states of 147Nd and 145Ce: Octupole correlation in the N=87 isotones

    High-spin states of the N=87 nuclei, 147Nd and 145Ce, have been populated in the 12C+238U and 18O+208Pb fusion-fission reactions at 90 MeV and 85 MeV bombarding energy, respectively. The emitted ?-radiation was detected using the Euroball III and IV arrays. High-spin states of the 147Nd isotope have been identified for the first time. The high-spin yrast and near-to-yrast structures of the 145Ce nucleus have been considerably extended. The newly observed structures, discussed by analogy with the neighbouring isotones, show the coupling of an h9/2 neutron to the quadrupole and octupole excitations of the core. (orig.)

  8. First observation of excited states in {sup 137}Te and the extent of octupole instability in the lanthanides

    Urban, W. [Institute of Experimental Physics, Warsaw University, ul.Hoza 69, 00-681 Warszawa, (Poland); Korgul, A. [Institute of Experimental Physics, Warsaw University, ul.Hoza 69, 00-681 Warszawa, (Poland); Rzaca-Urban, T. [Institute of Experimental Physics, Warsaw University, ul.Hoza 69, 00-681 Warszawa, (Poland); Schulz, N. [Institut de Recherches Subatomiques UMR7500, CNRS-IN2P3 et Universite Louis Pasteur, 67037 Strasbourg, (France); Bentaleb, M. [Institut de Recherches Subatomiques UMR7500, CNRS-IN2P3 et Universite Louis Pasteur, 67037 Strasbourg, (France); Lubkiewicz, E. [Institut de Recherches Subatomiques UMR7500, CNRS-IN2P3 et Universite Louis Pasteur, 67037 Strasbourg, (France); Durell, J. L. [Schuster Laboratory, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, (United Kingdom); Leddy, M. J. [Schuster Laboratory, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, (United Kingdom); Jones, M. A. [Schuster Laboratory, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, (United Kingdom); Phillips, W. R. [Schuster Laboratory, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, (United Kingdom)] (and others)

    2000-04-01

    Excited states in {sup 137}Te, populated in spontaneous fission of {sup 248}Cm, were studied by means of prompt-{gamma} spectroscopy, using the EUROGAM2 multidetector array. This is the first observation of excited states in {sup 137}Te. The yrast excitations of {sup 137}Te are due to the three valence neutrons, occupying the {nu}f{sub 7/2} and {nu}h{sub 9/2} orbitals, similarly as observed in its heavier N=85 isotones. Systematic comparison of excited levels in the N=85 isotones shows inconsistencies in spin and parity assignments in {sup 139}Xe and {sup 141}Ba nuclei. The new data for {sup 137}Te do not confirm earlier suggestions that octupole correlations increase in the N=85 isotones, close to the Z=50 closed shell. (c) 2000 The American Physical Society.

  9. First observation of excited states in 137Te and the extent of octupole instability in the lanthanides

    Excited states in 137Te, populated in spontaneous fission of 248Cm, were studied by means of prompt-γ spectroscopy, using the EUROGAM2 multidetector array. This is the first observation of excited states in 137Te. The yrast excitations of 137Te are due to the three valence neutrons, occupying the νf7/2 and νh9/2 orbitals, similarly as observed in its heavier N=85 isotones. Systematic comparison of excited levels in the N=85 isotones shows inconsistencies in spin and parity assignments in 139Xe and 141Ba nuclei. The new data for 137Te do not confirm earlier suggestions that octupole correlations increase in the N=85 isotones, close to the Z=50 closed shell. (c) 2000 The American Physical Society

  10. Effect of hydrogen on deformation structure and properties of CMSX-2 nickel-base single-crystal superalloy

    Dollar, M.; Bernstein, I. M.; Walston, S.; Prinz, F.; Domnanovich, A.

    1987-01-01

    Material used in this study was a heat of the alloy CMSX-2. This nickel-based superalloy was provided in the form of oriented single crystals, solutionized for 3 hrs at 1315 C. It was then usually heat treated as follows: 1050 C/16h/air cool + 850 C/48h/air cool. The resulting microstructure is dominated by cuboidal, ordered gamma precipitates with a volume fraction of about 75% and an average size of 0.5 microns. In brief, the most compelling hydrogen induced-changes in deformation structure are: (1) enhanced dislocation accumulation in the gamma matrix; and (2) more extensive cross-slip of superdislocations in the gamma precipitates. The enhanced dislocation density in gamma acts to decrease the mean free path of a superdislocation, while easier cross slip hinders superdislocation movement by providing pinning points in the form of sessile jobs. Both processes contribute to the increase of flow stress and the notable work hardening that occurs prior to fracture.

  11. Effect of grain size distribution on mechanical properties of ultrafine grained Al severely deformed by ARB process and subsequently annealed

    A commercial purity aluminum was highly deformed by the accumulative roll-bonding (ARB) process and subsequently annealed. The specimens having various grain size distributions were obtained. In case of the specimen ARB-processed with lubrication, the specimens with mean grain size larger than 3μm showed continuous yielding. On the other hand, in case of the specimen ARB-processed without lubrication, the specimens with mean grain size larger than 3μm showed discontinuous yielding. It suggests that appearance of the yield-drop phenomena can not be decided by the mean grain size. In order to consider effect of grain size distribution, the volume fraction of grains was summed from coarser grains, and the grain size when the summed volume fraction reached 70%, d70% was estimated from the grain size distribution. it was found that d70% of specimens which showed continuous yielding were larger than 8 μm while the specimens which showed discontinuous yielding were smaller than 6 μm, regardless of the lubrication condition in the ARB process. The result suggests that the appearance of the yield-drop phenomena depend on d70%.

  12. Correlation of substructure with mechanical properties of plastically deformed reactor structural materials. Progress report, January 1, 1976--June 30, 1977

    Transmission electron microscopy used to evaluate the deformation (creep, fatigue and tensile) induced microstructure of 304 SS, Incoloy 800, 330 SS and three of the experimental alloys (E19, E23 and E36) obtained from the National Alloy Program clearly shows that the relationship between the subgrain size (lambda) and the applied stress (sigma) obeys the equation lambda = Ab (sigma/E)-1 where A is a constant of the order of 4, b the Burgers rector and E is Young's modulus. Hot-hardness studies on 304 SS, 316 SS, Incoloy 800, 2 1/4 Cr-1 Mo steels, 330 SS, Inconel 718, PE-16, Inconel 706, M-813 and the above three experimental alloys suggests that reasonable effective activation energies for creep may be obtained through the use of the hardness test as a strength microprobe tool. The ordering of the strength levels obtained through hot-hardness follows quite closely that obtained in tensile tests when those data are available

  13. Effect of directional solidification rate on the microstructure and properties of deformation-processed Cu–7Cr–0.1Ag in situ composites

    Liu, Keming [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Jiang, Zhengyi; Zhao, Jingwei [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Zou, Jin; Chen, Zhibao [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); Lu, Deping, E-mail: llludp@163.com [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China)

    2014-11-05

    Highlights: • Effect of directional solidification (DS) rate on a Cu–Cr–Ag in situ composite. • The microstructure and properties of the DS in situ composite were investigated. • The second-phase Cr grains were parallel to drawing direction, and were finer. • The tensile strength was higher and the combination of properties was better. - Abstract: The influence of directional solidification rate on the microstructure, mechanical properties and conductivity of deformation-processed Cu–7Cr–0.1Ag in situ composites produced by thermo-mechanical processing was systematically investigated. The microstructure was analyzed by optical microscopy and scanning electronic microscopy. The mechanical properties and conductivity were evaluated by tensile-testing machine and micro-ohmmeter, respectively. The results indicate that the size, shape and distribution of second-phase Cr grains are significantly different in the Cu–7Cr–0.1Ag alloys with different growth rates. At a growth rate of 200 μm s{sup −1}, the Cr grains transform into fine Cr fiber-like grains parallel to the pulling direction from the Cr dendrites. The tensile strength of the Cu–7Cr–0.1Ag in situ composites from the directional solidification (DS) alloys is significantly higher than that from the as-cast alloy, while the conductivity of the in situ composites from the DS alloys is slightly lower than that from the as-cast alloy. The following combinations of tensile strength, elongation to fracture and conductivity of the Cu–7Cr–0.1Ag in situ composites from the DS alloy with a growth rate of 200 μm s{sup −1} and a cumulative cold deformation strain of 8 after isochronic aging treatment for 1 h can be obtained respectively as: (i) 1067 MPa, 2.9% and 74.9% IACS; or (ii) 1018 MPa, 3.0%, and 76.0% IACS or (iii) 906 MPa, 3.3% and 77.6% IACS.

  14. Mineral preferred orientation and magnetic properties as indicators of varying strain conditions in naturally deformed iron ore

    Günther, A.; Brokmeier, H. G.; Petrovský, Eduard; Siemes, H.; Helming, K.; Quade, H.

    A74, Suppl. (2002), s. S1080-S1082. ISSN 0947-8396 Institutional research plan: CEZ:AV0Z3012916 Keywords : magnetic properties * iron ore * Brazil * magnetic susceptibility Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.231, year: 2002

  15. Nanostructure and related mechanical properties of an Al-Mg-Si alloy processed by severe plastic deformation

    Nurislamova, Gulnaz; Sauvage, Xavier; Murashkin, Maxim; Islamgaliev, Rinat; Valiev, Ruslan

    2008-01-01

    Microstructural features and mechanical properties of an Al-Mg-Si alloy processed by high-pressure torsion have been investigated using transmission electron microscopy, X-ray diffraction, three-dimensional atom probe, tensile tests and microhardness measurements. It is shown that HPT processing of the Al-Mg-Si alloy leads to a much stronger grain size refinement than of pure aluminium (down to 100 nm). Moreover, massive segregation of alloying elements along grain boundaries is observed. Thi...

  16. Elastic Properties in Tension and Shear of High Strength Nonferrous Metals and Stainless Steel - Effect of Previous Deformation and Heat Treatment

    Mebs, R W; Mcadam, D J

    1947-01-01

    A resume is given of an investigation of the influence of plastic deformation and of annealing temperature on the tensile and shear elastic properties of high strength nonferrous metals and stainless steels in the form of rods and tubes. The data were obtained from earlier technical reports and notes, and from unpublished work in this investigation. There are also included data obtained from published and unpublished work performed on an independent investigation. The rod materials, namely, nickel, monel, inconel, copper, 13:2 Cr-Ni steel, and 18:8 Cr-Ni steel, were tested in tension; 18:8 Cr-Ni steel tubes were tested in shear, and nickel, monel, aluminum-monel, and Inconel tubes were tested in both tension and shear. There are first described experiments on the relationship between hysteresis and creep, as obtained with repeated cyclic stressing of annealed stainless steel specimens over a constant load range. These tests, which preceded the measurements of elastic properties, assisted in devising the loading time schedule used in such measurements. From corrected stress-set curves are derived the five proof stresses used as indices of elastic or yield strength. From corrected stress-strain curves are derived the secant modulus and its variation with stress. The relationship between the forms of the stress-set and stress-strain curves and the values of the properties derived is discussed. Curves of variation of proof stress and modulus with prior extension, as obtained with single rod specimens, consist in wavelike basic curves with superposed oscillations due to differences of rest interval and extension spacing; the effects of these differences are studied. Oscillations of proof stress and modulus are generally opposite in manner. The use of a series of tubular specimens corresponding to different amounts of prior extension of cold reduction gave curves almost devoid of oscillation since the effects of variation of rest interval and extension spacing were removed. Comparison is also obtained between the variation of the several properties, as measured in tension and in shear. The rise of proof stress with extension is studied, and the work-hardening rates of the various metals evaluated. The ratio between the tensile and shear proof stresses for the various annealed and cold-worked tubular metals is likewise calculated. The influence of annealing or tempering temperature on the proof stresses and moduli for the cold-worked metals and for air-hardened 13:2 Cr-Ni steel is investigated. An improvement of elastic strength generally is obtained, without important loss of yield strength, by annealing at suitable temperature. The variation of the proof stress and modulus of elasticity with plastic deformation or annealing temperature is explained in terms of the relative dominance of three important factors: namely, (a) internal stress, (b) lattice-expansion or work-hardening, and (c) crystal reorientation. Effective values of Poisson's ratio were computed from tensile and shear moduli obtained on tubular specimens. The variation of Poisson's ratio with plastic deformation and annealing temperature is explained in terms of the degree of anisotropy produced by changes of (a) internal stress and (b) crystal orientation.

  17. An Investigation of Physico-Mechanical Properties of Ultrafine-Grained Magnesium Alloys Subjected to Severe Plastic Deformation

    Kozulyn, A. A.; Skripnyak, V. A.; Krasnoveikin, V. A.; Skripnyak, V. V.; Karavatskii, A. K.

    2015-01-01

    The results of investigations of physico-mechanical properties of specimens made from the structural Mg-based alloy (Russian grade Ma2-1) in its coarse-grained and ultrafine-grained states after SPD processing are presented. To form the ultrafine-grained structure, use was made of the method of orthogonal equal-channel angular pressing. After four passes through the die, a simultaneous increase was achieved in microhardness, yield strength, ultimate tensile strength and elongation to failure under conditions of uniaxial tensile loading.

  18. Interrelation between the isoscalar octupole phonon and the proton-neutron mixed-symmetry quadrupole phonon in near-spherical nuclei

    Smirnova, N.A.; Van Isacker, P. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France); Smirnova, N.A [Paris-11 Univ., 91 - Orsay (France). Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse]|[Institute for Nuclear Physics, Moscow State University (Russian Federation); Pietralla, N. [Institut fur Kernphysik, Universitat zu Koln (Germany)]|[Yale Univ., New Haven, CT (United States). Wright Nuclear Structure Lab; Mizusaki, T. [Tokyo Univ. (Japan). Dept. of Physics

    2000-07-01

    The interrelation between the octupole phonon and the low-lying proton-neutron mixed-symmetry quadrupole in near-spherical nuclei is investigated. The one-phonon states decay by collective E3 and E2 transitions to the ground state and by relatively strong E1 and M1 transitions to the isoscalar 2{sup +}{sub 1} state. We apply the proton-neutron version of the Interacting Boson Model including quadrupole and octupole bosons (sdf-IBM-2). Two F-spin symmetric dynamical symmetry limits of the model, namely the vibrational and the {gamma}-unstable ones, are considered. We derived analytical formulae for excitation energies as well as B(E1), B(M1), B(E2), and B(E3) values for a number of transitions between low-lying states. The model well reproduces many known transition strengths in the near spherical nuclei {sup 142}Ce and {sup 94}Mo. (authors)

  19. Interrelation between the isoscalar octupole phonon and the proton-neutron mixed-symmetry quadrupole phonon in near-spherical nuclei

    The interrelation between the octupole phonon and the low-lying proton-neutron mixed-symmetry quadrupole in near-spherical nuclei is investigated. The one-phonon states decay by collective E3 and E2 transitions to the ground state and by relatively strong E1 and M1 transitions to the isoscalar 2+1 state. We apply the proton-neutron version of the Interacting Boson Model including quadrupole and octupole bosons (sdf-IBM-2). Two F-spin symmetric dynamical symmetry limits of the model, namely the vibrational and the γ-unstable ones, are considered. We derived analytical formulae for excitation energies as well as B(E1), B(M1), B(E2), and B(E3) values for a number of transitions between low-lying states. The model well reproduces many known transition strengths in the near spherical nuclei 142Ce and 94Mo. (authors)

  20. Effect of warm deformation on microstructure and mechanical properties of a layered and nanostructured 304 stainless steel

    Chen, A.Y.; Shi, S.S.; Tian, H.L. [School of Material Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Ruan, H.H. [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Hong Kong (China); Li, X. [School of Material Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Pan, D., E-mail: feiyu.dpan@gmail.com [School of Material Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Lu, J. [College of Science and Engineering, City University of Hong Kong, Hong Kong (China)

    2014-02-10

    A layered and nanostructured (LN) stainless steel was fabricated by surface mechanical attrition treatment (SMAT) combined with warm co-rolling (WCR) in order to improve the low ductility of nanostructured metallic materials. The influences of rolling temperature and strain on the microstructure are investigated. The microstructure of LN steel is characterized by methods of transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results reveal that the microstructure of LN steels presents a periodic distribution of nanocrystalline layer, ultra-fine grained layer and coarse grained layer with graded transition of grain size. The integrated effects of SMAT and WCR on the refinement of grain size, involving in dislocation subdivision, twinning and dynamic recrystallization, are discussed. The tensile properties of LN steels exhibit both high strength and good ductility resulting from good work hardening behavior. The strengthening mechanisms by grain size refinement, ??-martensite transformation and twinning are explored.

  1. Comparison between the sandy and the shaly facies of the Opalinus Clay (Mont Terri, Switzerland): mechanical properties obtained from triaxial deformation, mineralogical composition and micro fabric

    Document available in extended abstract form only. In Switzerland, the international research project Mont Terri investigates the Opalinus Clay (Jurassic formation) in the underground rock laboratory (URL) Mont Terri. The Opalinus Clay is subdivided into different facies (sandy, shaly, and carbonate rich facies). In the Mont Terri URL the sandy facies is less abundant and only a relatively thin layer of the carbonate rich facies is present. The currently favored HLRW repository site in Switzerland, however, is supposed to be in the sandy facies of the Opalinus Clay. Yet, most of the investigations focused on the shaly facies. Generally the understanding of the relation of properties and performances of clays and clay-stones is poor which is relevant for mineralogical micro fabric but also mechanical processes. For the safety assessment of the repository models describing both chemical and mechanical processes are required. Such models have to be based on a solid understanding of the mechanisms behind the processes considered. With respect to the understanding of the deformation behavior of different Opalinus Clay samples, Klinkenberg et al. (2009) found the carbonates to play a major role. For different samples of the shaly facies they found carbonate to represent a kind of predetermined breaking planes. Therefore, carbonate rich materials showed lower mechanical strengths. Interestingly, they also observed the opposite when considering samples of the Callovo-Oxfordian clay, which is investigated in France. Considering the micro fabric of all samples suggests that the carbonate - mechanical strength relation depends on the type and amount of carbonates. Therefore, Kaufhold et al. investigated the micro fabric - mechanical strength relation of the sandy facies. They concluded that the sandy facies is comparable with the investigated samples of the Callovo-Oxfordian clay. The mechanical behavior of the shaly facies was already investigated. A detailed comparison of samples from both main facies of the Opalinus clay, however, is missing. In this study, therefore, the investigation of the sandy facies and shaly facies with focus on the relation between micro fabric, mineralogical composition, and mechanical deformation behavior is presented. The sandy and the shaly facies both show the same mineral inventory but different contents. The shaly facies has a clay mineral content between 60 to 70 wt% (within 10-15 wt% swellable phases), whereas the sandy facies only has a clay mineral content of 15-25% (within dev.peak approximately twice as high as it was found for the shaly facies. The results are supposed to improve the understanding of the mechanical properties of clays, particularly with respect to the variability of mineral composition, micro fabric, and mechanical behavior. (authors)

  2. Effect of heat treatment on deformation and mechanical properties of 8 mol% yttria-stabilized zirconia by Berkovich nanoindentation

    Mao, W. G.; Luo, J. M.; Dai, C. Y.; Shen, Y. G.

    2015-05-01

    The effect of thermal treatment on the elasto-plastic transition and mechanical properties of air plasma-sprayed 8 mol% Y2O3-stabilized ZrO2 (8YSZ) thermal barrier coatings was studied by nanoindentation test at ultra-low loads with a Berkovich indenter. The area contact function of the indenter was calibrated repeatedly under nano-scales, and the indenter tip radius was estimated under different indentation depths, respectively. Owing to the heterogeneous and porous microstructure, the scatter of all collected experimental data was analyzed by Weibull statistic method. It is interesting to observe that the hardness exhibits an apparent reverse indentation size effect under very small depths. The Young's modulus of 8YSZ varies with ranging from 213 to 246 GPa due to the sintering effect. True hardness of 8YSZ increases from as-received 72.9 GPa to a top value 79.7 GPa under 100 thermal cycles, and then slightly decreases from this value to 75.5 GPa under 175 thermal cycles. The pure elastic and elasto-plastic indentation curves were obtained by adjusting the indentation load magnitude. The elasto-plastic transition and resolved shear stress fields were discussed carefully from the use of energetic models and Hertzian contact theory.

  3. Microstructure and mechanical properties of nanocrystalline titanium and Ti-Ta-Nb alloy manufactured using various deformation methods

    Mechanical properties and TEM microstructure studies have been carried out of nanocrystalline titanium, Ti10Nb10Ta and Ti10Nb obtained by various technological routes, including: powder metallurgy (ball milling and hot pressing), Equal Channel Angular Pressing (ECAP), hydroextrusion (HE) and high pressure torsion (HPT). The HE processed material in the form of 20 mm rods was extruded at a strain rate of 2.5 x 102 s-1 to a diameter of 3 mm, which corresponds to the true strain of 3.8. Resulting Yield Strength (YS) at the crystal size below 80 nm exceeded 1000 MPa, i.e. attained a value of 3 times more than the initial material. Equal-Channel Angular Pressing (ECAP) at 723 K was applied to produce nanostructured titanium. Grain refinement was observed already after one pass (considerable number of grains with d 20=1000. The additions of Nb and Ta resulted in a similar grain refinement but lower hardness. Uniaxial hot pressing at 650 C, followed by vacuum annealing resulted in similar microhardness as for powders. TEM studies performed using quantitative metallography allowed to estimate mean grain size at 150 nm. HPT technique at the pressure of 5 GPa resulted in finest grain size as compared to other preparation techniques leading to nanoscale grain refinement in Ti samples. The mean crystal size was estimated at about 30 nm. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  4. Effect of heat treatment and plastic deformation on the structure and the mechanical properties of nitrogen-bearing 04N9Kh2A steel

    Blinov, V. M.; Bannykh, O. A.; Lukin, E. I.; Kostina, M. V.; Blinov, E. V.

    2014-11-01

    The effect of the conditions of heat treatment and plastic deformation on the structure and the mechanical properties of low-carbon martensitic nickel steel (9 wt % Ni) with an overequilibrium nitrogen content is studied. The limiting strain to failure of 04N9Kh2A steel is found to be 40% at a rolling temperature of 20C and 80% at a rolling temperature of 900C. Significant strengthening of the steel (?0.2 = 1089 MPa) is obtained after rolling at a reduction of 40% at 20C. The start and final temperatures of the ? ? ? transformation on heating and those of the ? ? ? transformation on cooling are determined by dilatometry. The specific features of the formation of the steel structure have been revealed as functions of the annealing and tempering temperatures. Electron-microscopic studies show that, after quenching from 850C and tempering at 600C for 1 h, the structure contains packet martensite with thin interlayers of retained austenite between martensite crystals. The strength of the nitrogen-bearing 04N9Kh2A steel after quenching from 850 and 900C, cooling in water, and subsequent tempering at 500C for 1 h is significantly higher than that of carboncontaining 0H9 steel used in cryogenic engineering.

  5. The Effect Of Strain Rate On The Mechanical Properties And Microstructure Of The High-Mn Steel After Dynamic Deformation Tests

    Jabłońska M.B.

    2015-06-01

    Full Text Available The paper presents results of dynamic tensile investigations of high-manganese Fe – 20 wt.% Mn – 3 wt.% Al – 3 wt.% Si – 0.2 wt.% steel. The research was carried out on a flywheel machine, which enables to perform dynamic tensile tests and impact bending with a linear velocity of the enforcing element in the range of 5÷40 m/s. It was found that the studied steel was characterized by very good mechanical properties. Strength of the tested materials was determined in the static tensile test and dynamic deformation test, while its hardness was measured with the Vickers hardness test method. The surface of fractures that were created in the areas where the sample was torn were analyzed. These fractures indicate the presence of transcrystalline ductile fractures. Fractographic tests were performed with the use of a scanning electron microscope. The structure was analyzed by light optical microscopy. Substructure studies revealed occurrence of mechanical twinning induced by high strain rates. A detailed analysis of the structure was performed with the use of a transmission scanning electron microscope STEM.

  6. Developing a Methodology for Observing Fault-Zone Frictional Properties from Repeating Earthquakes at Depth: Application to Postseismic Deformation Following the 2004 Parkfield Earthquake

    Statz-Boyer, P.; Taira, T.; Nadeau, R. M.; Dreger, D. S.

    2009-12-01

    Observing fault-zone frictional and rheological properties at seismogenic depth is a key to understand postseismic deformation. We propose a methodology for estimating subsurface rheological/frictional properties, using cumulative seismic slips derived from repeating earthquake sequences. An ideal test for measuring frictional and rheological properties has been provided by the 2004 M 6 Parkfield earthquake, California, because the Parkfield region has many repeating earthquake sequences. We use a set of 12 repeating earthquake sequences extending over a depth range of 5 km, at the Parkfield segment of the San Andreas fault. These sequences are chosen because 5-10 repeating earthquakes in individual sequences typically occurred during the first month of the postseismic period, which allows us to address time evolutions of cumulative seismic slips. Their locations are close to the rupture area of the 2004 Parkfield earthquake. Following Montési [2004], we first test three rheology models to characterize cumulative seismic slips inferred from repeating earthquake sequences: 1) velocity-strengthening friction, 2) viscous flow, and 3) ductile creep, where velocity-strengthening friction and viscous flow are end-members of the power law case. Observed cumulative seismic slips are characterized by a stress exponent n. For velocity-strengthening friction, 1/n = 0 and, for viscous flow, 1/n = 1. Assuming loading rate to be zero, we first invert cumulative seismic slip data over a time period of 3 years following the 2004 Parkfield earthquake to determine 1/n, characteristic time τ, and initial slip rate V0 (e.g., immediately after the main shock). We employ a least-square method, estimating 95% confidence intervals using a bootstrap approach. Our result suggests that 9 of 12 sequences yield 1/n ranging from -0.5 to 0.01, which suggest a velocity-strengthening friction model with the presence of reloading on the fault. The remaining 3 sequences show a relatively large range of confidence intervals for 1/n (-0.5 to 0.1). Thus we focus on the 9 sequences for further analysis. We next address the effect of loading rate on postseismic deformation, given a velocity-strengthening friction model [Marone et al., 1991]. We find that either the determined loading rates are two orders of magnitude lower than V0 or they are negative. We conclude that the effects of loading rate can be negligible. Assuming an effective normal stress of 100 MPa and a stiffness of 5 MPa/m, we finally infer frictional parameter (a - b) from τ and V0 to be 0.005-0.01, a value that is generally consistent with laboratory experiments [Marone et al., 1991] and geodetic measurements for the 2004 Parkfield case [Barbot et al., 2009]. Continuing work will include exploration of slip distributions for individual sequences with finite-source modeling. A comparison of the slip distributions of repeating earthquakes with frictional parameters should allow us to develop a more comprehensive picture of the role of frictional properties on the earthquake nucleation process.

  7. Cyclic Plastic Deformation and Welding Simulation

    Ten Horn, C.H.L.J.

    2003-01-01

    One of the concerns of a fitness for purpose analysis is the quantification of the relevant material properties. It is known from experiments that the mechanical properties of a material can change due to a monotonic plastic deformation or a cyclic plastic deformation. For a fitness for purpose analysis to be accurate in these cases, it has to take into account the current mechanical properties of the material. The problem is that the current properties may not always be known and retrieving ...

  8. Cyclic Plastic Deformation and Welding Simulation:

    Ten Horn, C.H.L.J.

    2003-01-01

    One of the concerns of a fitness for purpose analysis is the quantification of the relevant material properties. It is known from experiments that the mechanical properties of a material can change due to a monotonic plastic deformation or a cyclic plastic deformation. For a fitness for purpose analysis to be accurate in these cases, it has to take into account the current mechanical properties of the material. The problem is that the current properties may not always be known and retrieving ...

  9. Properties of seven-filament in situ MgB{sub 2}/Fe composite deformed by hydrostatic extrusion, drawing and rolling

    Kovac, P [Institute of Electrical Engineering, Centre of Excellence CENG, Slovak Academy of Sciences, Dubravska cesta 9, 841 04 Bratislava (Slovakia); Husek, I [Institute of Electrical Engineering, Centre of Excellence CENG, Slovak Academy of Sciences, Dubravska cesta 9, 841 04 Bratislava (Slovakia); Pachla, W [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw (Poland); Kulczyk, M [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw (Poland)

    2007-07-15

    Seven-filament MgB{sub 2}/Fe wires and tapes were made by in situ processing using hydrostatic extrusion, rolling and drawing. Microhardness measurements have shown that the density of as-deformed cores reflects the applied deformation and follows the iron sheath hardness. The filament size was reduced from 245 {mu}m down to 19 {mu}m by rolling and the critical current densities of samples with different core sizes and deformation routes were compared. The highest current density was measured for the tape deformed by two-axial rolling and a filament size of 60 {mu}m. Thinner filaments show lower J{sub c} values due to hard inclusions present in low-purity boron powder (boron oxide), which reduce the transport current substantially. The obtained results show that a proper combination of extrusion and rolling deformations leads to high filament density in wires and tapes, which results in high transport current density.

  10. Anyons and deformed lie algebras

    Frau, M; Sciuto, S; Marialuisa Frau; Alberto Lerda; Stefano Sciuto

    1994-01-01

    We discuss the connection between anyons (particles with fractional statistics) and deformed Lie algebras (quantum groups). After a brief review of the main properties of anyons, we present the details of the anyonic realization of all deformed classical Lie algebras in terms of anyonic oscillators. The deformation parameter of the quantum groups is directly related to the statistics parameter of the anyons. Such a realization is a direct generalization of the Schwinger construction in terms of fermions and is based on a sort of bosonization formula which yields the generators of the deformed algebra in terms of the undeformed ones. The entire procedure is well defined on two-dimensional lattices, but it can be consistently reduced also to one-dimensional chains.

  11. Carrier Deformability in Drug Delivery.

    Morilla, Maria Jose; Romero, Eder Lilia

    2016-01-01

    Deformability is a key property of drug carriers used to increase the mass penetration across the skin without disrupting the lipid barrier. Highly deformable vesicles proved to be more effective than conventional liposomes in delivering drugs into and across the mammalian skin upon topical non occlusive application. In the past five years, highly deformable vesicles have been used for local delivery of drugs on joint diseases, skin cancer, atopic dermatitis, would healing, psoriasis, scar treatment, fungal, bacteria and protozoa infections. Promising topical vaccination strategies rely also in this type of carriers. Here we provide an overview on the main structural and mechanical features of deformable vesicles, to finish with an extensive update on their latest preclinical applications. PMID:26675226

  12. Oxide dispersion strengthened ferritic alloys. 14/20% chromium: effects of processing on deformation texture, recrystallization and tensile properties; Alliages ferritiques 14/20% de chrome renforces par dispersion d`oxydes. Effets des procedes de mise en forme sur les textures de deformation, la recristallisation et les proprietes de traction

    Regle, H.

    1994-12-31

    The ferritic oxide dispersion strengthened alloys are promising candidates for high temperature application materials, in particular for long life core components of advanced nuclear reactors. The aim of this work is to control the microstructure, in order to optimise the mechanical properties. The two ferritic alloys examined here, MA956 and MA957, are obtained by Mechanical Alloying techniques. They are characterised by quite anisotropic microstructure and mechanical properties. We have investigated the influence of hot and cold working processes (hot extrusion, swaging and cold-drawing) and recrystallization heat treatments on deformation textures, microstructures and tensile properties. The aim was to control the size of the grains and their anisotropic shape, using recrystallization heat treatments. After consolidation and hot extrusion, as-received materials present a extremely fine microstructure with elongated grains and a very strong (110) deformation texture with single-crystal character. At that stage of processing, recrystallization temperature are very high (1450 degrees C for MA957 alloy and 1350 degrees C for MA956 alloy) and materials develop millimetric recrystallized grains. Additional hot extrusion induce a fibre texture. Cold-drawing maintains a fibre texture, but the intensity decreases with increasing cold-work level. For both materials, the decrease of texture intensities correspond to a decrease of the recrystallization temperatures (from 1350 degrees C for a low cold-work level to 750 degrees C for 60 % cold-deformation, case of MA956 alloy) and a refinement of the grain size (from a millimetric size to less than an hundred of micrometer). Swaging develop a cyclic component where the intensity increases with increasing deformation in this case, the recrystallization temperature remains always very high and the millimetric grain size is slightly modified, even though cold-work level increases. (Abstract Truncated)

  13. Distributed actuator deformable mirror

    Bonora, Stefano

    2010-01-01

    In this paper we present a Deformable Mirror (DM) based on the continuous voltage distribution over a resistive layer. This DM can correct the low order aberrations (defocus, astigmatism, coma and spherical aberration) using three electrodes with nine contacts leading to an ideal device for sensorless applications. We present a mathematical description of the mirror, a comparison between the simulations and the experimental results. In order to demonstrate the effectiveness of the device we compared its performance with the one of a multiactuator DM of similar properties in the correction of an aberration statistics. At the end of the paper an example of sensorless correction is shown.

  14. Deformed General Relativity

    Bojowald, Martin; Paily, George M.

    2012-01-01

    Deformed special relativity is embedded in deformed general relativity using the methods of canonical relativity and loop quantum gravity. Phase-space dependent deformations of symmetry algebras then appear, which in some regimes can be rewritten as non-linear Poincare algebras with momentum-dependent deformations of commutators between boosts and time translations. In contrast to deformed special relativity, the deformations are derived for generators with an unambiguous physical role, follo...

  15. Fluctuations as stochastic deformation

    Kazinski, P. O.

    2007-01-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic partic...

  16. Effect of petrophysical properties and deformation on vertical zoning of metasomatic rocks in U-bearing volcanic structures: A case of the Strel'tsovka caldera, Transbaikal region

    Petrov, V. A.; Andreeva, O. V.; Poluektov, V. V.

    2014-03-01

    The development of vertical zoning of wall-rock metasomatic alteration is considered with the Mesozoic Strel'tsovka caldera as an example. This caldera hosts Russia's largest uranium ore field. Metasomatic rocks with the participation of various phyllosilicates, carbonates, albite, and zeolites are widespread in the ore field. In the eastern block of the caldera, where the main uranium reserves are accommodated, hydromica metasomatic alteration gives way to beresitization with depth. Argillic alteration, which is typical of the western block, is replaced with hydromica and beresite alteration only at a significant depth. Postore argillic alteration is superposed on beresitized rocks in the lower part of the section. Two styles of vertical metasomatic zoning are caused by different modes of deformation in the western and eastern parts of the caldera. Variations of the most important petrophysical properties of host rocks—density, apparent porosity, velocities of P- and S-waves, dynamic Young's modulus, and Poisson coefficient—have been determined by sonic testing of samples taken from different depths. It is suggested that downward migration of the brittle-ductile transition zone could have been a factor controlling facies diversity of metasomatic rocks. Such a migration was caused by a new phase of tectonothermal impact accompanied by an increase in the strain rate or by emplacement of a new portion of heated fluid. Transient subsidence of the brittle-ductile boundary increases the depth of the hydrodynamically open zone related to the Earth's surface and accelerates percolation of cold meteoric water to a greater depth. As a result, the temperature of the hydrothermal solution falls down, increasing the vertical extent of argillic alteration. High-grade uranium mineralization is also localized more deeply than elsewhere.

  17. Impact of chamber pressure and material properties on the deformation response of corneal models measured by dynamic ultra-high-speed Scheimpflug imaging

    Fernando Faria Correia

    2013-10-01

    Full Text Available PURPOSE: To study the deformation response of three distinct contact lenses with known structures, which served as corneal models, under different chamber pressures using ultra-high-speed (UHS Scheimpflug imaging. METHODS: Three hydrophilic contact lenses were mounted on a sealed water chamber with precisely adjustable pressure: TAN-G5X (41% hydroxyethylmethacrylate/glycolmethacrylate, 550 µm thick, TAN-40 (62% hydroxyethylmethacrylate, 525 µm thick and TAN-58 (42% methylmethacrylate, 258 µm thick. Each model was tested five times under different pressures (5, 15, 25, 35 and 45 mmHg, using ultra-high-speed Scheimpflug imaging during non-contact tonometry. 140 Scheimpflug images were taken with the UHS camera in each measurement. The deformation amplitude during non-contact tonometry was determined as the highest displacement of the apex at the highest concavity (HC moment. RESULTS: At each pressure level, the deformation amplitude was statistically different for each lens tested (p<0.001, ANOVA. Each lens had different deformation amplitudes under different pressure levels (p<0.001; Bonferroni post-hoc test. The thicker lens with less polymer (TAN-G5X had a higher deformation (less stiff behavior than the one that was thinner but with more polymer (TAN-40, when measured at the same internal pressure. The thinnest lens with less polymers (TAN-58 had a lower deformation amplitude (stiffer behavior at higher pressures than the thicker ones with more polymer (TAN-40 and TAN-G5X at lower pressures. CONCLUSIONS: UHS Scheimpflug imaging allowed for biomechanical assessment through deformation characterization of corneal models. Biomechanical behavior was more influenced by material composition than by thickness. Chamber pressure had a significant impact on deformation response of each lens.

  18. The influence of β phase stability on deformation mode and compressive mechanical properties of Ti–10V–3Fe–3Al alloy

    A metastable β-Ti alloy, Ti–10V–3Fe–3Al (wt.%), was subjected to thermomechanical processing (TMP), where the temperature of isothermal holding in the α + β phase field was varied in order to change the volume fraction of the α phase and, correspondingly, the β phase stability. Following TMP, compression tests were performed at room temperature to evaluate the deformation mode. Microstructural features induced by compression were identified using transmission electron microscopy. It was found that {3 3 2}〈1 1 3〉β deformation twinning along with stress-induced products (α″ martensite and ω lamellae) and slip were operational in the least stable β. The co-existence of {3 3 2}〈1 1 3〉β and {1 1 2}〈1 1 1〉β twinning was found at intermediate β stability along with other deformation products. With further increasing of β phase stability, no {3 3 2}〈1 1 3〉β twinning was detected whereas other deformation modes remained unchanged. In stable β phase, dislocation glide was the only deformation mode to be found. It was revealed that triggering stress required inducing the deformation products increases with the β phase stability. Based on the findings, a modification of the lower portion of the Bo‾–Md‾ phase stability diagram is proposed

  19. Lie algebras Classification, Deformations and Rigidity

    Goze, M

    2006-01-01

    In the first section we recall some basic notions on Lie algebras. In a second time we study the algebraic variety of complex $n$-dimensional Lie algebras. We present different notions of deformations : Gerstenhaber deformations, pertubations, valued deformations and we use these tools to study some properties of this variety. Finaly we introduce the concept of rigidity and we present some results on the class of rigid Lie algebras.

  20. Deformed aerogels in the superfluid 3He

    Fomin, I. A.; Surovtsev, E. V.

    2015-01-01

    Deformed aerogels induce a global anisotropy in the superfluid 3He and orient the orbital part of its order parameter. Here a phenomenological theory of the orientational effect of elastic deformations of aerogels on the superfluid phases of 3He in the spirit of conventional theory of elasticity is formulated. Phenomenological coefficients, entering basic relations, depend on properties of given aerogel in the non-deformed state. Examples of originally isotropic silica aerogel and axially sym...

  1. Mechanical properties, microstructure and thermal stability of a nanocrystalline CoCrFeMnNi high-entropy alloy after severe plastic deformation

    An equiatomic CoCrFeMnNi high-entropy alloy (HEA), produced by arc melting and drop casting, was subjected to severe plastic deformation (SPD) using high-pressure torsion. This process induced substantial grain refinement in the coarse-grained casting leading to a grain size of approximately 50 nm. As a result, strength increased significantly to 1950 MPa, and hardness to ∼520 HV. Analyses using transmission electron microscopy (TEM) and 3-dimensional atom probe tomography (3D-APT) showed that, after SPD, the alloy remained a true single-phase solid solution down to the atomic scale. Subsequent investigations characterized the evolution of mechanical properties and microstructure of this nanocrystalline HEA upon annealing. Isochronal (for 1 h) and isothermal heat treatments were performed followed by microhardness and tensile tests. The isochronal anneals led to a marked hardness increase with a maximum hardness of ∼630 HV at about 450 °C before softening set in at higher temperatures. The isothermal anneals, performed at this peak hardness temperature, revealed an additional hardness rise to a maximum of about 910 HV after 100 h. To clarify this unexpected annealing response, comprehensive microstructural analyses were performed using TEM and 3D-APT. New nano-scale phases were observed to form in the originally single-phase HEA. After times as short as 5 min at 450 °C, a NiMn phase and Cr-rich phase formed. With increasing annealing time, their volume fractions increased and a third phase, FeCo, also formed. It appears that the surfeit of grain boundaries in the nanocrystalline HEA offer many fast diffusion pathways and nucleation sites to facilitate this phase decomposition. The hardness increase, especially for the longer annealing times, can be attributed to these nano-scaled phases embedded in the HEA matrix. The present results give new valuable insights into the phase stability of single-phase high-entropy alloys as well as the mechanisms controlling the mechanical properties of nanostructured multiphase composites

  2. Third harmonic generation in organic octupole molecules with small absorption at 3ω

    The nonlinear optical properties of 1,3,5-tricyano-2,4,6-tri (p-diethylaminostyryl) benzene (TTB) thin films have been measured by using third-harmonic generation (THG) at the fundamental wavelength of 1064 nm. By comparing the THG intensity with that of fused silica, we estimated the third-order electrical susceptibility of the organic film to be 1.2 X10-11 esu, which is about 400 times larger than that of fused silica glass. Due to the unique properties of the TTB films, such as anomalous dispersion and small re-absorption of the third harmonic wave, a thick film is expected to give a more efficient THG, which can be applied to ultrafast optical correlators.

  3. A novel deformation mechanism for superplastic deformation

    Muto, H.; Sakai, M. (Toyohashi Univ. of Technology (Japan). Dept. of Materials Science)

    1999-01-01

    Uniaxial compressive creep tests with strain value up to -0.1 for a [beta]-spodumene glass ceramic are conducted at 1060 C. From the observation of microstructural changes between before and after the creep deformations, it is shown that the grain-boundary sliding takes place via cooperative movement of groups of grains rather than individual grains under the large-scale-deformation. The deformation process and the surface technique used in this work are not only applicable to explain the deformation and flow of two-phase ceramics but also the superplastic deformation. (orig.) 12 refs.

  4. Determination of the B(E3;0$^+\\!\\rightarrow$ 3$^{-}$) strength in the octupole correlated nucleus $^{144}$Ba using Coulomb excitation

    We propose to exploit the unique capability of ISOLDE to provide intense post-accelerated $^{144}$Ba ion beams from the REX facility to enable the Coulomb excitation of the first 3 $^{-}$ state in this nucleus. By measuring the $\\gamma$-ray yields of the E1 decay connecting the 3$^{-}$ and 2$^{+}$ states using the MINIBALL array, we can obtain the interesting transition matrix element. The result will give quantitative information about octupole correlations in this nucleus. We require 27 shifts to fulfill the aims of the experiment.

  5. Determination of the B(E3,0$^{+}$ $\\rightarrow$ 3$^{-}$) strength in the octupole correlated nuclei $^{142,144}$Ba using Coulomb excitation

    We propose to exploit the unique capability of ISOLDE to provide intense post-accelerated $^{142}$Ba and $^{144}$Ba ion beams from the HIE-ISOLDE facility to enable the Coulomb excitation of the first 3$^-$ state in these nuclei. By measuring the $\\gamma$-ray yields of the E1 decays from the 3$^-$ state using the MINIBALL array, we can obtain the interesting transition matrix element. The results will give quantitative information about octupole correlations in these nuclei. We require 33 shifts to fulfil the aims of the experiment.

  6. Developing a Virtual Rock Deformation Laboratory

    Zhu, W.; Ougier-simonin, A.; Lisabeth, H. P.; Banker, J. S.

    2012-12-01

    Experimental rock physics plays an important role in advancing earthquake research. Despite its importance in geophysics, reservoir engineering, waste deposits and energy resources, most geology departments in U.S. universities don't have rock deformation facilities. A virtual deformation laboratory can serve as an efficient tool to help geology students naturally and internationally learn about rock deformation. Working with computer science engineers, we built a virtual deformation laboratory that aims at fostering user interaction to facilitate classroom and outreach teaching and learning. The virtual lab is built to center around a triaxial deformation apparatus in which laboratory measurements of mechanical and transport properties such as stress, axial and radial strains, acoustic emission activities, wave velocities, and permeability are demonstrated. A student user can create her avatar to enter the virtual lab. In the virtual lab, the avatar can browse and choose among various rock samples, determine the testing conditions (pressure, temperature, strain rate, loading paths), then operate the virtual deformation machine to observe how deformation changes physical properties of rocks. Actual experimental results on the mechanical, frictional, sonic, acoustic and transport properties of different rocks at different conditions are compiled. The data acquisition system in the virtual lab is linked to the complied experimental data. Structural and microstructural images of deformed rocks are up-loaded and linked to different deformation tests. The integration of the microstructural image and the deformation data allows the student to visualize how forces reshape the structure of the rock and change the physical properties. The virtual lab is built using the Game Engine. The geological background, outstanding questions related to the geological environment, and physical and mechanical concepts associated with the problem will be illustrated on the web portal. In addition, some web based data collection tools are available to collect student feedback and opinions on their learning experience. The virtual laboratory is designed to be an online education tool that facilitates interactive learning.; Virtual Deformation Laboratory

  7. Anatomy of gravitationally deformed slopes

    Chigira, Masahiro; Yamasaki, Shintaro; Hariyama, Takehiro

    2010-05-01

    Deep-seated gravitational slope deformation is the deformation of rocks as well as slope surfaces, but the internal structures have not been well observed and described before. This is mainly due to the difficulty in obtaining undisturbed samples from underground. We analyzed the internal deformational structures of gravitationally deformed slopes by using high quality drilled cores obtained by hybrid drilling technique, which has been recently developed and can recover very fragile materials that could not be taken by the conventional drilling techniques. Investigated slopes were gravitationally deformed out-facing slopes of pelitic schist and shale. The slope surfaces showed deformational features of small steps, depressions, knobs, and linear depressions, but had no major main scarp and landslide body with well-defined outline. This is indicative of slow, deep-seated gravitational deformation. Most of these small deformational features are hidden by vegetations, but they are detected by using airborne laser scanner. Drilled cores showed that the internal deformation is dominated by the slip and tearing off along foliations. Slippage along foliations is conspicuous in pelitic schist: Pelitic schist is sheared, particularly along black layers, which are rich in graphite and pyrite. Graphite is known to be a solid lubricant in material sciences, which seems to be why shearing occurs along the black layers. Rock mass between two slip layers is sheared, rotated, fractured, and pulverized; undulation of bedding or schistosity could be the nucleation points of fracturing. Tearing off along foliations is also the major deformation mode, which forms jagged morphology of rock fragments within shear zones. Rock fragments with jagged surface are commonly observed in "gouge", which is very different from tectonic gouge. This probably reflects the low confining pressures during their formation. Microscopic to mesoscopic openings along fractures are commonly observed with fractures, which also suggests the low confining pressures. Vertical distribution of gravitational deformation with above features indicates that gravitational shear zones are nucleated in a distributed manner, then gradually connected to each other, and finally cut through the whole slope. This is the transition of gravitational mass rock creep to rock slide. First nucleation points seem to be controlled by the heterogeneity of rock properties. Thick black layers in pelitic schist, shale near thick sandstone beds in sedimentary rocks, were such nuclear points. The geometrical relationships between the distribution of fracture zones and the slope morphology suggest that they are formed in accordance to the valley incision and resultant slope destabilization.

  8. Effect of heat treatment on diffusion, internal friction, microstructure and mechanical properties of ultra-fine-grained nickel severely deformed by equal-channel angular pressing

    Severe plastic deformation via equal-channel angular pressing was shown to induce characteristic ultra-fast diffusion paths in Ni (Divinski et al., 2011). The effect of heat treatment on these paths, which were found to be represented by deformation-modified general high-angle grain boundaries (GBs), is investigated by accurate radiotracer self-diffusion measurements applying the 63Ni isotope. Redistribution of free volume and segregation of residual impurities caused by the heat treatment triggers relaxation of the diffusion paths. A correlation between the GB diffusion kinetics, internal friction, microstructure evolution and microhardness changes is established and analyzed in detail. A phenomenological model of diffusion enhancement in deformation-modified GBs is proposed

  9. Changes in physical-mechanical properties and structure of ferritic-pearlitic steel 15Kh2NMFA caused by severe low-temperature deformation and exposure to alternating magnetic field

    Sokolenko, V. I.; Mats, A. V.; Karas', V. I.; Okovit, V. S.; Chernyak, N. A.; Gorbatenko, V. M.

    2015-04-01

    It is shown for the low-plasticity ferritic-pearlitic steel 15Kh2NMFA (2Cr, 1Ni, 0.5Mn, 0.5Mo), subjected to severe rolling deformation at 90 K, that the treatment by the alternating magnetic field results in a substantial decrease of the yield strength and an increase of fracture stress, total elongation, necking and dynamic shear modulus. This is accompanied by reduction of the internal friction background and coercive force. The changes in the physical-mechanical properties and the structure are related to magnetic- and electrical-nature processes giving rise to stress relaxation in the microvolumes with a high density of deformation defects.

  10. A study on nonlinear finite element analysis of laminated rubber bearings. Pt.1. Development of evaluation method for mechanical properties of laminated rubber bearings for horizontal base isolation system considering volumetric deformation of rubber material

    The purpose of this research is to develop the evaluation method for mechanical properties of laminated rubber bearings by nonlinear finite element method (FEM) considering the volumetric deformation of natural rubber material. Relationship between pressure and volumetric strain of the natural rubber is obtained from the volumetric tests and is introduced into user-subroutine of the FEM code (ABAQUS). Finite element analyses of natural rubber bearings (NRB) and the natural rubber bearing with lead plug (LRB) are carried out. The results may be summarized as follows; 1) Horizontal, vertical stiffness and effect of shear deformation on vertical stiffness of natural rubber bearings that have various shape are simulated with enough accuracy. 2) Horizontal and vertical stiffness of LRB are also simulated well. (author)

  11. Deformations of three-dimensional metrics

    Pugliese, Daniela

    2014-01-01

    We examine three-dimensional metric deformations based on a tetrad transformation through the action the matrices of scalar fields. We describe by this approach to deformation the results obtained by Coll et al. in [1], where it is stated that any three--dimensional metric was locally obtained as a deformation of a constant curvature metric parameterized by a 2--form.To this aim, we construct the corresponding deforming matrices and provide their classification according to the properties of the scalar $\\sigma$ and of the vector $\\mathbf{s}$ used in [1] to deform the initial metric. The resulting causal structure of the deformed geometries is examined, too.Finally we apply our results to a spherically symmetric three geometry and to a space sector of Kerr metric.

  12. Plastic deformation effects on magnetic Barkhausen noise

    Plastically deformed steel specimens were analyzed using surface magnetic Barkhausen noise (MBN). Three types of samples were investigated: mild steel specimens uniaxially deformed up to 40% strain, mild steel specimens deformed in bending to 0.2% longitudinal strain, cold-rolled nuclear reactor pressure vessel steel specimens from 0% to 60% reduction ratio. The angular dependence of an 'MBNenergy' term was used to examine magnetic anisotropy changes with increasing deformation, with linear MBN scans used to monitor changes in magnetic properties along the specimen axis. Average MBNenergy values were observe to vary significantly with stress within the elastic region, yet only slightly in the plastic range of deformation. Changes in the shape of the pulse height distribution curves were evidence of plastic deformation effects on domain wall pinning sites. We conclude that a complex interplay between stress and strain mechanisms, residual stresses and crystallographic texture generates variations in MBN signal

  13. Effect of nuclear deformation parameters in heavy-ion fusion reactions involving spherical-spherical systems

    It is well known that heavy-ion collisions at energies near the Coulomb barrier are strongly affected by the internal structure of the colliding nuclei. The coupling between the relative motion and the internal degrees of freedom such as static deformation, vibration of nuclear surface, zero point motion, rotations of nuclei during collision, etc. results in the splitting of the uncoupled Coulomb barrier into distribution of barriers of varying heights. The role of complex quadrupole and octupole surface vibrations is of particular interest and the calculations within the coupled channels model may become challenging in most nuclei. In order to study the role of important degrees of freedom of spherical nuclei in the fusion mechanism, fusion cross section and barrier distribution (BD) have been calculated for 16O + 120Sn and 16O + 208Pb systems using the code CCFULL

  14. Effect of deformation schedules and initial states on structure and properties of Cu–0.18% Zr alloy after high-pressure torsion and heating

    Structure, microhardness and electrical resistivity of the Cu–0.18% Zr alloy after high pressure torsion (HPT) were investigated for different initial states (hot-pressed, annealed, quenched) and deformation schedules. It is shown that HPT leads to formation of submicrocrystalline structure with the grain size of 200–250 nm. Studying of electrical resistivity of the Cu–0.18% Zr alloy showed that during HPT it increases with increasing the strain in comparison with initial not deformed state. It can be connected with changes of grain and subgrain structure, and also with processes of dissolution of particles of the second phase Cu5Zr during deformation. Decreasing of electrical resistivity values of Cu–0.18% Zr alloy after HPT during heating in the temperatures range of 250–400 °C and preservation or increase of microhardness values in this temperature interval reveal aging processes with allocation of Cu5Zr particles and confirm the fact of partial supersaturation of solid solution of copper with zirconium during deformation. Application of quenching, HPT and subsequent aging allows to achieve the maximum strengthening of the alloy

  15. Triaxially deformed relativistic point-coupling model for Λ hypernuclei: A quantitative analysis of the hyperon impurity effect on nuclear collective properties

    Xue, W. X.; Yao, J. M.; Hagino, K.; Li, Z. P.; Mei, H.; Tanimura, Y.

    2015-02-01

    Background: The impurity effect of hyperons on atomic nuclei has received a renewed interest in nuclear physics since the first experimental observation of appreciable reduction of E 2 transition strength in low-lying states of the hypernucleus Λ7Li . Many more data on low-lying states of Λ hypernuclei will be measured soon for s d -shell nuclei, providing good opportunities to study the Λ impurity effect on nuclear low-energy excitations. Purpose: We carry out a quantitative analysis of the Λ hyperon impurity effect on the low-lying states of s d -shell nuclei at the beyond-mean-field level based on a relativistic point-coupling energy density functional (EDF), considering that the Λ hyperon is injected into the lowest positive-parity (Λs) and negative-parity (Λp) states. Method: We adopt a triaxially deformed relativistic mean-field (RMF) approach for hypernuclei and calculate the Λ binding energies of hypernuclei as well as the potential-energy surfaces (PESs) in the (β ,γ ) deformation plane. We also calculate the PESs for the Λ hypernuclei with good quantum numbers by using a microscopic particle rotor model (PRM) with the same relativistic EDF. The triaxially deformed RMF approach is further applied in order to determine the parameters of a five-dimensional collective Hamiltonian (5DCH) for the collective excitations of triaxially deformed core nuclei. Taking 25,27Mg Λ and Si31Λ as examples, we analyze the impurity effects of Λs and Λp on the low-lying states of the core nuclei. Results: We show that Λs increases the excitation energy of the 21+ state and decreases the E 2 transition strength from this state to the ground state by 12 %to17 % . On the other hand, Λp tends to develop pronounced energy minima with larger deformation, although it modifies the collective parameters in such a way that the collectivity of the core nucleus can be either increased or decreased. Conclusions: The quadrupole deformation significantly affects the Λ binding energies of deformed hypernuclei. A beyond-mean-field approach with the dynamical correlations due to restoration of broken symmetries and shape fluctuation is essential in order to study the Λ impurity effect in a quantitative way.

  16. Deformations in N=14 isotones

    Kanada-Enyo, Y

    2005-01-01

    Systematic analysis of deformations in neutron-rich N=14 isotones was done based on the method of antisymmetrized molecular dynamics. The property of the shape coexistence in $^{28}$Si, which is known to have the oblate ground state and the prolate excited states, was successfully described. The results suggest that the shape coexistence may occur also in neutron-rich N=14 nuclei as well as $^{28}$Si. It was found that the oblate neutron shapes are favored because of the spin-orbit force in most of N=14 isotones. $Q$ moments and $E2$ transition strengths in the neutron-rich nuclei were discussed in relation to the intrinsic deformations, and a possible difference between the proton and neutron deformations in $^{24}$Ne was proposed.

  17. Nuclear fuel deformation phenomena

    Nuclear fuel encounters severe thermomechanical environments. Its mechanical response is profoundly influenced by an underlying heterogeneous microstructure but also inherently dependent on the temperature and stress level histories. The ability to adequately simulate the response of such microstructures, to elucidate the associated macroscopic response in such extreme environments is crucial for predicting both performance and transient fuel mechanical responses. This chapter discusses key physical phenomena and the status of current modelling techniques to evaluate and predict fuel deformations: creep, swelling, cracking and pellet-clad interaction. This chapter only deals with nuclear fuel; deformations of cladding materials are discussed elsewhere. An obvious need for a multi-physics and multi-scale approach to develop a fundamental understanding of properties of complex nuclear fuel materials is presented. The development of such advanced multi-scale mechanistic frameworks should include either an explicit (domain decomposition, homogenisation, etc.) or implicit (scaling laws, hand-shaking,...) linkage between the different time and length scales involved, in order to accurately predict the fuel thermomechanical response for a wide range of operating conditions and fuel types (including Gen-IV and TRU). (authors)

  18. Effect of structural factors on mechanical properties of the magnesium alloy Ma2-1 under quasi-static and high strain rate deformation conditions

    Garkushin, G. V.; Razorenov, S. V.; Krasnoveikin, V. A.; Kozulin, A. A.; Skripnyak, V. A.

    2015-02-01

    The elastic limit and tensile strength of deformed magnesium alloys Ma2-1 with different structures and textures were measured with the aim of finding a correlation between the spectrum of defects in the material and the resistance to deformation and fracture under quasi-static and dynamic loading conditions. The studies were performed using specimens in the as-received state after high-temperature annealing and specimens subjected to equal-channel angular pressing at a temperature of 250°C. The anisotropy of strength characteristics of the material after shock compression with respect to the direction of rolling of the original alloy was investigated. It was shown that, in contrast to the quasi-static loading conditions, under the shock wave loading conditions, the elastic limit and tensile strength of the magnesium alloy Ma2-1 after equal-channel angular pressing decrease as compared to the specimens in the as-received state.

  19. Deformation scheme effect on the properties of heat pipes of 12KH1MF steel, hardened by mechanical and heat treatments

    In the development, by the method of mechanical and heat treatment, of strenghening conditions for tubes from steel 12Kh1MF cold drawing and cold reducing are used at a uniform deformation factor of 11% but with materially different schemes of stress-strain state (different distributions and signs of strains and stresses). The greatest strenthening effect as regards to the ultimate stress and yield stress at a uniform deformation is obtained in the drawing. The poligonizing annealing makes for the levelling out of the drawn and reduced metal, the strength characteristics deteriorate to a greater degree for the drawn metal. The heat resisting characteristics of metal of drawn and reduced tubes at a test temperature of 540degC and high stresses (20-24kgs/mm2) are similar, the plasticity, however, being higher with then drawn tubes. At stresses close to the working ones, metal of the reduced tubes features longer time periods before failure. (author)

  20. The influence of the temperature of plastic deformation on the structure and mechanical properties of copper alloys CuCo2Be and CuCo1Ni1Be

    W. Ozgowicz; B.Grzegorczyk

    2009-01-01

    Purpose: The aim of the paper is to determine the influence of temperature of plastic deformation on the structure and mechanical properties of copper alloy of the CuCo2Be and CuCo1Ni1Be during a tensile test applied on electrodes to welders.Design/methodology/approach: The tensile test of the investigated copper alloys was realized in the temperature range of 20-800C with a strain rate of 1.210-3s1 on the universal testing machine. Metallographic observations of the structure were carried...

  1. Effect of surface plastic deformation on the structure and properties of welded tubular joints of 12Kh18N10T steel

    Samples of tubular electrowelded half-finished articles 40x2 and 40x2.5 mm in size are studied. It is shown that the welded tubes may be calibrated without destruction and other negative events with essential deformations. To prevent initial deviation from the form it necessary to remove preliminarily welding flash from the tube internal surface or use the instrument with enlarged angle of entry cone

  2. Plastic deformation: Shearing mountains atom by atom

    Highlights: ► Rocks, wood, ceramics, semiconductors, and metals all deform in the same way, namely by heterogeneous shear banding via hierarchical orthogonal shear modes. ► While the governing principles of deformation are the same for rocks, wood, ceramics, semiconductors, and metals, these materialsdiffer in their microscopic deformation mechanisms and in the width of the shear band, which covers twelve orders of magnitude from angstroms to hundreds of meters. ► Microscopic deformation mechanisms couple to macroscopic deformation mechanisms, i.e. shear banding, through the collective properties of defect groups on the mesoscale. -- Abstract: Conventional wisdom established atomistic defects, dislocations, as agents of plastic deformation. On macroscopic scale, rock, wood, steel, tough ceramics, fiber reinforced composites, and silicon all deform in the same way and produce the same pattern; shear bands. The argumentation presented here, starts on the largest length scale of the problem at hand and leads through a number of hierarchical levels down to the atomistic mechanism. Shear bands develop discontinuously by the motion of a process zone. Locally, i.e. in the process zone, deformation proceeds perpendicularly to the macroscopic shear, in combination with a rotation. The microscopic shear itself may occur again in a discontinuous manner and again orthogonally to the intermediate level and so on at ever smaller scale. Material properties come into play at the highest hierarchical level, i.e. at the smallest length scale where they control the well-known micromechanisms

  3. Alar Rim Deformities.

    Totonchi, Ali; Guyuron, Bahman

    2016-01-01

    The alar rim plays an important role in nasal harmony. Alar rim flaws are common following the initial rhinoplasty. Classification of the deformities helps with diagnosis and successful surgical correction. Diagnosis of the deformity requires careful observation of the computerized or life-sized photographs. Techniques for treatment of these deformities can easily be learned with attention to detail. PMID:26616701

  4. Prediction of exotic octupole excitation modes in superdeformed A ? 150 and A ? 190 nuclei: Bending, Banana and other modes

    Results of the first calculations aiming at determination of the exotic shape effects at large elongations are presented. After discussing some formal aspects of our generalised approach based on the deformed Woods-Saxon potential, the overall trends in the quantal (shell) effects leading to the deformation driving forces in terms of Y?=3,? multipole components are presented. Finally, the nuclei are identified in which (at least at a low spin limit) the predicted exotic shape effects should manifest themselves in the most pronounced way. 10 figs

  5. Deformations in quantum physics

    We consider deformations of quantum mechanical objects, and use the novel construction of warped convolutions for deformation. It turns out that through the deformation we are able to obtain several quantum mechanical effects where electromagnetic fields play a role. We understand the magnetic field as an object which is the outcome of strict mathematical deformation. Furthermore, we are able to obtain all magnetic fields by using this method of deformation. The results are used in quantum field theory to obtain an effective quantum plane.

  6. Fluctuations as stochastic deformation

    Kazinski, P O

    2008-01-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is equivalent to the deformation of an algebra of observables in the manner of deformation quantization with an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic d...

  7. The Effect of Silver Nanofibers on the Deformation Properties of Blood Vessels: Towards the Development of New Nanotechnologies to Prevent Rupture of Aneurysms

    Miguel Gonzalez; Daniel Rivera; Alam Marcelino; Gabriela Agront; Rafael Rodriguez; Miguel Castro

    2014-01-01

    An aneurysm is the result of a widening or ballooning of a portion of a blood vessel. The rupture of an aneurysm occurs when the mechanical stress acting on the inner wall exceeds the failure strength of the blood vessel. We propose an innovative approach to prevent the rupture of an aneurysm based on the use of nanotechnology to improve the strength of the blood vessel. We present results on the effect of silver nanofibers on the resistance toward deformation of blood vessels. The silver nan...

  8. Effect of hydroextrusion pressure on the mechanism of molybdenum monocrystals plastic deformation

    Considered are plastic deformation peculiarities of molybdenum monocrystals in the process of multiple-stage and single-stage deformation by hydroextrusion at 20-80% reduction under pressures of 1000-11000 atm. The effect of hydrostatic extrusion pressure upon the plastic deformation mechanism and mechanical properties is established. Multiple-stage deformation permits to considerably decrease the pressure value in practice as compared with the single-stage hydroextrusion, without deterioration of properties of deformed molybdenum monocrystals

  9. IBA in deformed nuclei

    The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for 168Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong β → γ transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the β → γ transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ΔK=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics

  10. Time-resolved soft-x-ray spectroscopy of a magnetic octupole transition in nickel-like xenon, cesium, and barium ions

    A microcalorimeter with event mode capability for time-resolved soft-x-ray spectroscopy, and a high-resolution flat-field extreme ultraviolet spectrometer have been employed at the Livermore EBIT-I electron beam ion trap for observations and wavelength measurements of M1, E2, and M3 decays of long-lived levels in the Ni-like ions Xe26+, Cs27+, and Ba28+. Of particular interest is the lowest excited level, 3d94s 3D3, which can only decay via a magnetic octupole (M3) transition. For this level in Xe, an excitation energy of (590.40±0.03 eV) and a level lifetime of (11.5±0.5 ms) have been determined

  11. Time-resolved soft-x-ray spectroscopy of a magnetic octupole transition in nickel-like xenon, cesium, and barium ions

    Trabert, E; Beiersdorfer, P; Brown, G V; Boyce, K; Kelley, R L; Kilbourne, C A; Porter, F S; Szymkowiak, A

    2005-11-11

    A microcalorimeter with event mode capability for time-resolved soft-x-ray spectroscopy, and a high-resolution flat-field EUV spectrometer have been employed at the Livermore EBIT-I electron beam ion trap for observations and wavelength measurements of M1, E2, and M3 decays of long-lived levels in the Ni-like ions Xe{sup 26+}, Cs{sup 27+}, and Ba{sup 28+}. Of particular interest is the lowest excited level, 3d{sup 9}4s {sup 3}D{sub 3}, which can only decay via a magnetic octupole (M3) transition. For this level in Xe an excitation energy of (590.40 {+-} 0.03eV) and a level lifetime of (11.5 {+-} 0.5 ms) have been determined.

  12. Neptunium octupole and hexadecapole motifs in NpO2 directly from electric dipole (E1) enhanced x-ray Bragg diffraction

    The phase transition in NpO2 at T0 ? 25.5 K is accompanied by the onset of superlattice reflections in the x-ray Bragg diffraction pattern, with intensity enhanced by an electric dipole (E1) event. Additional experiments using other techniques indicate no ordering at T0 of Np magnetic moments. Absence of long-range magnetic order below T0 fits with the outcome of a polarization analysis of superlattice intensities at 12 K; signals are observed in both the unrotated (?'?) and rotated (?'?) channels of scattering while magnetic (dipole) moments would contribute only in the rotated channel. We demonstrate that these empirical findings, together with a narrow energy profile of the Bragg intensity at the Np M4 edge, are consistent with magnetic and charge contributions to the E1 Bragg amplitude described by Np 5f multipoles of ranks 3 (octupole) and 4 (hexadecapole). Key to our understanding of the x-ray diffraction data gathered in the vicinity of the Np M4 edge is recognition of an exchange field creating 3d3/2 core-level structure. The particular importance of the exchange field at the Np M4 edge is emphatically revealed in calculations of the corresponding x-ray absorption spectrum with and without the core-valence interaction. From the experimental information about NpO2 we can infer a ground-state wavefunction for the Np 5f3 valence shell and estimate saturation values for the octupole and hexadecapole. We are led to null values for Np multipoles of ranks 2 (quadrupole) and 5 (triakontadipole)

  13. Deformed aerogels in the superfluid 3He

    Fomin, I. A.; Surovtsev, E. V.

    2015-08-01

    Deformed aerogels induce a global anisotropy in the superfluid 3He and orient the orbital part of its order parameter. Here a phenomenological theory of the orientational effect of elastic deformations of aerogels on the superfluid phases of 3He in the spirit of conventional theory of elasticity is formulated. Phenomenological coefficients, entering basic relations, depend on properties of given aerogel in the nondeformed state. Examples of originally isotropic silica aerogel and axially symmetric "nematically ordered" aerogel are considered. Values of phenomenological coefficients are estimated with the aid of a simple microscopic model. An example of a nonuniform deformation of nematically ordered aerogel is discussed.

  14. Layered Structures in Deformed Metals and Alloys

    Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu

    2014-01-01

    Layered structures characterize metals and alloys deformed to high strain. The morphology is typical lamellar or fibrous and the interlamellar spacing can span several length scales down to the nanometer dimension. The layered structures can be observed in bulk or in surface regions, which is shown......-structure relationships. Finally, the results will be discussed based on universal principles for the evolution of microstructure and properties during plastic deformation of metals and alloys from low to high strain....

  15. Thermal conductivity of deformed carbon nanotubes

    Zhong, Wei-rong; Zhang, Mao-Ping; Zheng, Dong-Qin; Ai, Bao-quan

    2011-01-01

    We investigate the thermal conductivity of four types of deformed carbon nanotubes by using the nonequilibrium molecular dynamics method. It is reported that various deformations have different influence on the thermal properties of carbon nanotubes. For the bending carbon nanotubes, the thermal conductivity is independent on the bending angle. However, the thermal conductivity increases lightly with XY-distortion and decreases rapidly with Z-distortion. The thermal conductivity does not chan...

  16. Deformation of C15 Laves phase alloys

    Chu, F.; Pope, D.P.

    1995-12-31

    Details of the structure and previous work on the deformation of C Laves phases are reviewed. The phase diagram of the Hf-V-Nb system, some metallurgical and physical properties, mechanical behavior, and the deformation mechanisms of HfV{sub 2}+Nb (CI5 HfV{sub 2}+Nb and V-rich bcc solution) are presented based on our previous work. Theoretical approaches to understanding the results of these studies are discussed.

  17. Quantum mechanics in q-deformed calculus

    Lavagno, A [Dipartimento di Fisica, Politecnico di Torino, I-10129 Torino (Italy); Gervino, G, E-mail: andrea.lavagno@polito.i, E-mail: gervino@to.infn.i [Dipartimento di Fisica, Universita di Torino, I-10126 Torino (Italy)

    2009-06-01

    Starting on the basis of q-deformed calculus and q-symmetric oscillator algebra, we introduce a generalized Schroedinger equation which admits factorized time-space solutions and the free plane wave functions can be expressed in terms of the so-called basic-hypergeometric functions. In this framework, q-deformed adjoint and q-hermitian operator properties occur in a natural way in order to satisfy the fundamental quantum mechanics assumptions.

  18. Deformation Behavior of Human Dentin under Uniaxial Compression

    Dmitry Zaytsev; Sergey Grigoriev; Peter Panfilov

    2012-01-01

    Deformation behavior of a human dentin under compression including size and rate effects is studied. No difference between mechanical properties of crown and root dentin is found. It is mechanically isotropic high elastic and strong hard tissue, which demonstrates considerable plasticity and ability to suppress a crack growth. Mechanical properties of dentin depend on a shape of samples and a deformation rate.

  19. -Deformed nonlinear maps

    Ramaswamy Jaganathan; Sudeshna Sinha

    2005-03-01

    Motivated by studies on -deformed physical systems related to quantum group structures, and by the elements of Tsallis statistical mechanics, the concept of -deformed nonlinear maps is introduced. As a specific example, a -deformation procedure is applied to the logistic map. Compared to the canonical logistic map, the resulting family of -logistic maps is shown to have a wider spectrum of interesting behaviours, including the co-existence of attractors – a phenomenon rare in one-dimensional maps.

  20. Fluctuations as stochastic deformation.

    Kazinski, P O

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium. PMID:18517590

  1. Fluctuations as stochastic deformation

    Kazinski, P. O.

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium.

  2. Deformed discrete symmetries

    Arzano, Michele

    2016-01-01

    We construct discrete symmetry transformations for deformed relativistic kinematics based on group valued momenta. We focus on the specific example of kappa-deformations of the Poincare algebra with associated momenta living on (a sub-manifold of) de Sitter space. Our approach relies on the description of quantum states constructed from deformed kinematics and the observable charges associated with them. The results we present provide the first step towards the analysis of experimental bounds on the deformation parameter kappa to be derived via precision measurements of discrete symmetries and CPT.

  3. Diffeomorphic Statistical Deformation Models

    Hansen, Michael Sass; Hansen, Mads/Fogtman; Larsen, Rasmus

    In this paper we present a new method for constructing diffeomorphic statistical deformation models in arbitrary dimensional images with a nonlinear generative model and a linear parameter space. Our deformation model is a modified version of the diffeomorphic model introduced by Cootes et al. The...... modifications ensure that no boundary restriction has to be enforced on the parameter space to prevent folds or tears in the deformation field. For straightforward statistical analysis, principal component analysis and sparse methods, we assume that the parameters for a class of deformations lie on a linear...

  4. Periodic orbit approach to prolate dominance in nuclear deformation

    Semiclassical origin of deformed nuclear shell structures are investigated. In the periodic orbit theory, quantum level density is expressed as the sum over classical periodic orbits, and properties of shell structures can be analyzed in terms of short periodic orbits. In particular, we focus on the role of periodic orbit bifurcations which are responsible for exotic deformed shell structures found at certain values of deformation parameters. We show that the prolate shape dominance in nuclear deformations can be clearly understood from deformed shell structures caused by periodic orbits and their bifurcations in realistic nuclear mean field potential models.

  5. An extended deformable shell model for ionic crystals including quadrupolar deformation of the charge cloud

    It is well known that the dipolar and scalar deformation of the charge cloud around an ion in ionic crystals are quite significant in describing the different lattice mechanical properties. Even after the inclusion of the above deformations systematic discrepancies between theory and experiment persist. An attempt is made to incorporate the effect of the quadrupolar distortion of the charge cloud in the framework of the deformable shell model. All the relevant equations and lattice sums are evaluated for the CsCl structure and a preliminary application of the complete model which takes into account simultaneously the scalar, the dipolar and the quadrupolar deformation considered for a CsCl structure crystal. So far there is no estimate of the effect of the quadrupolar distortion on the different properties of a crystal belonging to CsCl structure. The calculation indicates that the effect is quite considerable for certain properties and its inclusion improves the overall agreement with experiment. (author)

  6. Deform PF-MT: particle filter with mode tracker for tracking nonaffine contour deformations.

    Vaswani, Namrata; Rathi, Yogesh; Yezzi, Anthony; Tannenbaum, Allen

    2010-04-01

    We propose algorithms for tracking the boundary contour of a deforming object from an image sequence, when the nonaffine (local) deformation over consecutive frames is large and there is overlapping clutter, occlusions, low contrast, or outlier imagery. When the object is arbitrarily deforming, each, or at least most, contour points can move independently. Contour deformation then forms an infinite (in practice, very large), dimensional space. Direct application of particle filters (PF) for large dimensional problems is impractically expensive. However, in most real problems, at any given time, most of the contour deformation occurs in a small number of dimensions ("effective basis space") while the residual deformation in the rest of the state space ("residual space") is small. This property enables us to apply the particle filtering with mode tracking (PF-MT) idea that was proposed for such large dimensional problems in recent work. Since most contour deformation is low spatial frequency, we propose to use the space of deformation at a subsampled set of locations as the effective basis space. The resulting algorithm is called deform PF-MT. It requires significant modifications compared to the original PF-MT because the space of contours is a non-Euclidean infinite dimensional space. PMID:19933014

  7. Relativistic description of deformed nuclei

    The author has shown that relativistic Hartree calculations using parameters that have been fit to the properties of nuclear matter can provide a good description of both spherical and axially deformed nuclei. The quantitative agreement with experiment is equivalent to that which was obtained in non-relativistic calculations using Skyrme interactions. The equilibrium deformation is strongly correlated with the size of the spin-orbit splitting, and that parameter sets which give roughly the correct value for this splitting provide the best agreement with the quadrupole moments in the s-d shell. Finally, for closed shell +/- 1 nuclei, it was shown that the self-consistent calculations are able to reproduce the experimental magnetic moments. This was not possible in relativistic calculations which include only the effects of the valence orbital

  8. Greenland Analogue Project - Hydraulic properties of deformation zones and fracture domains at Forsmark, Laxemar and Olkiluoto for usage together with Geomodel version 1

    Follin, Sven (SF GeoLogic AB (Sweden)); Stigsson, Martin (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Rhen, Ingvar (Sweco Environment AB (Sweden)); Engstroem, Jon (Geologian tutkimuskeskus (Finland)); Klint, Knut Erik (De Nationale Geologiske Undersoegelser for Danmark og Groenland (Denmark))

    2011-05-15

    The database of the GAP site is under development. In order to meet the data needs of the different modelling teams working with groundwater flow modelling it has been decided to compile trial data sets comprising structural-hydraulic properties suitable for flow modelling on different scales. The properties provided in this report are based on data and groundwater flow modelling studies conducted for three sites located in the Fennoscandian Shield, two of which are studied by SKB, Forsmark and Laxemar, and one by Posiva, Olkiluoto. The provided hydraulic properties provided here are simplified to facilitate a readily usage together with the GAP Geomodel version 1.

  9. q-Deformed Schroedinger equation

    In a q-deformed quantum mechanics the commutation relations between the generators of the SUq(2) algebra, L-vector and the position vector, r, are well defined and it is natural to take this vectors as the basic quantities from which all the others must be built. To build a q-deformed Schroedinger Hamiltonian a realization of p-vector entering the kinetic energy term was necessary to find. p-Vector can be written as a sum of two terms which are parallel and perpendicular to r-vector, respectively. We first obtained the general commutation relations involving the q-angular momentum and some quantities having definite transformation properties with respect to SUq(2) algebra. We then give a realization of the position vector and of the q-angular momentum, L, in terms of polar coordinates. Then, we obtained the realization of the linear momentum p made of a part perpendicular to r-vector, satisfying similar commutation relations to those corresponding to r-vector, and of a part parallel to r-vector supposed to have the simplest form, i.e., that coming from the ordinary partial derivative with respect to r-vector. We calculated the Eigenfunctions of the q-angular momentum, written like a series expansion in terms of cos?. The result is a generalization of two hypergeometric functions which can be related to the q-deformed spherical functions Ylm. Some properties and relations satisfied by the Eigenfunctions are also listed. In the last section the q-deformed Schroedinger equation with scalar potential is given. Its solutions for Coulomb and three dimensional oscillator potential are briefly discussed

  10. Dynamics of structural phase transition and changes in properties under the influence of elastically anisotropic deforming stresses, regularities of critical lines and points in magnetic semiconductors and magnetic dielectrics

    Polyakov, P. I.; Kucherenko, S. S.

    2004-07-01

    The paper deals with a generalizing analysis of elastically deforming regularities by examining the experimental results for magnetic semiconductors and dielectrics. The role of anisotropically deforming elastic (EAD) stresses, determined from the influence of temperature ( T), magnetic field ( H) and hydrostatic pressure ( P), in the formation and changes of the structural phase transitions (PTs) and properties has been estimated. From the analysis of investigations of the resistive and magnetostrictive properties and of PTs in La 0.7Ca 0.3MnO 3, LaMnO 3 the role of EAD in baro-, magneto-, and baromagnetoresistive effects has been determined and it has been deduced that their maximum temperature TPP is equal to the temperature of metal-semiconductor PT Tms. It is noted that the action of EAD stresses in the "cooling", "heating" effects of Tms( H), Tms( P) and Hg( T) change, and in T- H- P (5.1 K-2.42 kOe-1 kbar) influence on the resistive properties, and T- H (5.2 K-2.5 kOe) influence on the magnetostrictive properties is regular. Changes in properties, PT, and T- H- P-induced effects were found to be of the alternating-sign character. From the results of studies of the resonance properties and PTs in CuCl 2·2H 2O the role of EAD stresses has been determined and a correspondence in the T- H- P (1 K-4 kOe-3 kbar) effect on PT change has been revealed. Thermomagnetic and thermobaromagnetic effects have been revealed with the peaks corresponding to TPP=0 K, the temperature which coincides with that of the structural PT TST. The regularities in "cooling" and "heating" effects of H and P influence have been grounded, as well as those in TP( H), TP( H, P) change going on with sign alternation. The location of point P( HP, TP), where elastic and magnetoelastic anisotropies become conformable to each other at TP=9.2 K, has been found. It considerably differs from the known TN=4.3 K. The results of magnetization and of the field-temperature and field-frequency dependencies investigation have been analyzed, and it has been shown that there is a correspondence in the changes of properties under the influence of T, H, and P before and after the structural PT. The effect of thermally straining striction (compression) (TSS) has been revealed, which is a consequence of structure properties and of the mechanisms of thermoanisotropic strains. The role of EAD stresses in the competitive mechanisms of T and H effects and in changes of the high-frequency properties is shown. The critical lines (i) in magnetic semiconductors, Tms( H), Tms( P) and Hg( T) and points TX, PX, PPX, PX', TPP= Tms, TC, as well as (ii) in magnetic dielectrics, TP( H), TP( H,P) and points PX, PPX, TX= TPP= TST=0 K, P, TP=9.2 K have been marked out and explained. A relationship between the peculiarities of structure, PTs, properties and mechanisms of EAD stresses from the influence of T- H- P has been found. The role of sign alternation of thermo- and magneto-elasticity and of their anisotropies in changes of properties and PT has been shown. The identity in position (sign alternation) of critical lines Hg( T), HP( T) and points PX, PPX, TX, TC, P has been noted. The laws of EAD stresses in changes of properties and PT of magnetic semiconductors and dielectrics have been ascertained.

  11. Deformation of CHS model

    Suyama, Takao

    2002-01-01

    We calculate mass spectrum of CHS model deformed by an exactly marginal operator, and find that there are tachyons which are not localized in the target space. Similar deformation is discussed in another CFT which corresponds to separated NS5-branes. A condensation of the tachyons is briefly argued.

  12. Resurgent deformation quantisation

    We construct a version of the complex Heisenberg algebra based on the idea of endless analytic continuation. The algebra would be large enough to capture quantum effects that escape ordinary formal deformation quantisation. -- Highlights: •We construct resurgent deformation quantisation. •We give integral formulæ. •We compute examples which show that hypergeometric functions appear naturally in quantum computations

  13. Resurgent deformation quantisation

    Garay, Mauricio, E-mail: garay91@gmail.com [Institut für Mathematik, FB 08 Physik, Mathematik und Informatik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Goursac, Axel de, E-mail: Axelmg@melix.net [Chargé de Recherche au F.R.S.-FNRS, IRMP, Université Catholique de Louvain, Chemin du Cyclotron, 2, B-1348 Louvain-la-Neuve (Belgium); Straten, Duco van, E-mail: straten@mathematik.uni-mainz.de [Institut für Mathematik, FB 08 Physik, Mathematik und Informatik, Johannes Gutenberg-Universität, 55099 Mainz (Germany)

    2014-03-15

    We construct a version of the complex Heisenberg algebra based on the idea of endless analytic continuation. The algebra would be large enough to capture quantum effects that escape ordinary formal deformation quantisation. -- Highlights: •We construct resurgent deformation quantisation. •We give integral formulæ. •We compute examples which show that hypergeometric functions appear naturally in quantum computations.

  14. Deformations of algebroid stacks

    Bressler, Paul; Gorokhovsky, Alexander; Nest, Ryszard; Tsygan, Boris

    2011-01-01

    In this paper we consider deformations of an algebroid stack on an étale groupoid. We construct a differential graded Lie algebra (DGLA) which controls this deformation theory. In the case when the algebroid is a twisted form of functions we show that this DGLA is quasiisomorphic to the twist of ...

  15. Secondary deformation of molybdenum

    The features of secondary deformation of molybdenum with initially produced dislocation structure are studied. It is shown that any prestrained deformation can be represented using two additional parameters-equivalent strain eeq and effective grain size deff. Application of these parameters in practice of thermomechanical treatment allows to produce the micron size grain

  16. Models of the Dynamic Deformations of Polymers

    Merzhievsky, Lev; Voronin, Mihail; Korchagina, Anna

    2013-06-01

    In the process of deformation under the influence of external loading polymeric mediums show the complicated behavior connected with features of their structure. For amorphous polymers distinguish three physical conditions - glasslike, highlyelastic and viscoplastic. To each of the listed conditions there corresponds to mikro - meso- and macrostructural mechanisms of irreversible deformation. In the report the review of results of construction of models for the description of dynamic and shock-wave deformation of the polymers which are based on developed authors representations about mechanisms of irreversible deformation is made. Models include the formulation of the equations of conservation laws, considering effect of a relaxation of shear stresses in the process of deformation. For closing of models the equations of states with nonspherical tensor of deformations and relation for time of a relaxation of shear stresses are constructed. With using of the formulated models a number of problems of dynamic and shock wave deformations has been solved. The results are compared with corresponding experimental date. Development of the used approach are in summary discussed. To taking into account memory and fractal properties of real polymers is supposed of derivatives and integrals of a fractional order to use. Examples of constitutive equations with derivatives of a fractional order are presented. This work is supported by the Integration project of the Siberian Branch of the Russian Academy of Science 64 and grant RFBR 12-01-00726.

  17. Deformations of Superconformal Theories

    Cordova, Clay; Intriligator, Kenneth

    2016-01-01

    We classify possible supersymmetry-preserving relevant, marginal, and irrelevant deformations of unitary superconformal theories in $d \\geq 3$ dimensions. Our method only relies on symmetries and unitarity. Hence, the results are model independent and do not require a Lagrangian description. Two unifying themes emerge: first, many theories admit deformations that reside in multiplets together with conserved currents. Such deformations can lead to modifications of the supersymmetry algebra by central and non-central charges. Second, many theories with a sufficient amount of supersymmetry do not admit relevant or marginal deformations, and some admit neither. The classification is complicated by the fact that short superconformal multiplets display a rich variety of sporadic phenomena, including supersymmetric deformations that reside in the middle of a multiplet. We illustrate our results with examples in diverse dimensions. In particular, we explain how the classification of irrelevant supersymmetric deformat...

  18. Triaxially deformed relativistic point-coupling model for $\\Lambda$ hypernuclei: a quantitative analysis of hyperon impurity effect on nuclear collective properties

    Xue, W X; Hagino, K; Li, Z P; Mei, H; Tanimura, Y

    2014-01-01

    The impurity effect of hyperon on atomic nuclei has received a renewed interest in nuclear physics since the first experimental observation of appreciable reduction of $E2$ transition strength in low-lying states of hypernucleus $^{7}_\\Lambda$Li. Many more data on low-lying states of $\\Lambda$ hypernuclei will be measured soon for $sd$-shell nuclei, providing good opportunities to study the $\\Lambda$ impurity effect on nuclear low-energy excitations. We carry out a quantitative analysis of $\\Lambda$ hyperon impurity effect on the low-lying states of $sd$-shell nuclei at the beyond-mean-field level based on a relativistic point-coupling energy density functional (EDF), considering that the $\\Lambda$ hyperon is injected into the lowest positive-parity ($\\Lambda_s$) and negative-parity ($\\Lambda_p$) states. We adopt a triaxially deformed relativistic mean-field (RMF) approach for hypernuclei and calculate the $\\Lambda$ binding energies of hypernuclei as well as the potential energy surfaces (PESs) in $(\\beta, \\g...

  19. Using TerraSAR-X and hyperspectral airborne data to monitor surface deformation and physical properties of the Barrow permafrost landscape, Alask

    Haghshenas-Haghighi, M.; Motagh, M.; Heim, B.; Sachs, T.; Kohnert, K.; Streletskiy, D. A.

    2014-12-01

    In this study, we assess seasonal subsidence/heaving due to thawing/freezing of the permafrost in Barrow (71.3 N, 156.5 W) at the northernmost point of Alaska. The topographic relief in this area is low. Thick Permafrost underlies the entire area, with large ice volumes in its upper layer. With a large collection of field measurements during the past decades at the Barrow Environmental Observatory (BEO), it is an ideal site for permafrost investigation. There are long term systematic geocryological investigations within the Global Terrestrial Network (GTN-P) of the Circumpolar Active Layer Monitoring (CALM) programme. We use 28 TerraSAR-X images, acquired between December 2012 and December 2013 and analyze them using the Small BAseline Subset (SBAS) technique to extract time-series of ground surface deformation. We also analyze hyperspectral images acquired by the airborne AISA sensor over Barrow area, within the AIRMETH2013 programme, to assess physical characteristics such as vegetation biomass and density, surface moisture, and water bodies. Finally, we combine the information derived from both InSAR and hyperspectral analysis, with field measurements to investigate the link between physical characteristics of the permafrost and surface displacement.

  20. Determination of the B(E3, 0+ → 3−)-excitation strength in octupole-correlated nuclei near A ≈ 224 by the means of Coulomb excitation at REX-ISOLDE

    The IS475 collaboration conducted Coulomb-excitation experiments with postaccelerated radioactive 220Rn and 224Ra beams at the REX-ISOLDE facility. The beam particles (Ebeam ≈ 2.83 MeV/u) were Coulomb excited using 60Ni, 114Cd, and 120Sn scattering targets. De-excitation γ-rays were detected employing the Miniball array and scattered particles were detected in a silicon detector. Exploiting the Coulomb-excitation code GOSIA for each nucleus several matrix elements could be obtained from the measured γ-ray yields. The extracted (3−||Ê3||0+) matrix element allows for the conclusion that, while 220Rn represents an octupole vibrational system, 224Ra has already substantial octupole correlations in its ground state. An observation that has implications for the search of CP-violating Schiff moments in the atomic systems of the adjacent odd-mass nuclei.