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1

Collective properties of octupole-deformed atomic nuclei  

International Nuclear Information System (INIS)

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

Octupole deformation properties of the Barcelona-Catania-Paris energy density functionals  

International Nuclear Information System (INIS)

We discuss the octupole deformation properties of the recently proposed Barcelona-Catania-Paris (BCP) energy density functionals for two sets of isotopes, those of radium and barium, in which it is believed that octupole deformation plays a role in the description of the ground state. The analysis is carried out in the mean field framework (Hartree-Fock-Bogoliubov approximation) by using the axially symmetric octupole moment as a constraint. The main ingredients entering the octupole collective Hamiltonian are evaluated and the lowest-lying octupole eigenstates are obtained. In this way we restore, in an approximate way, the parity symmetry spontaneously broken by the mean field and also incorporate octupole fluctuations around the ground-state solution. For each isotope the energy of the lowest lying 1- state and the B(E1) and B(E3) transition probabilities have been computed and compared to both the experimental data and the results obtained in the same framework with the Gogny D1S interaction, which are used here as a well-established benchmark. Finally, the octupolarity of the configurations involved in the way down to fission of 240Pu, which is strongly connected to the asymmetric fragment mass distribution, is studied. We confirm with this thorough study the suitability of the BCP functionals to describe octupole-related phenomena.

3

Octupole deformation properties of the Barcelona-Catania-Paris energy density functionals  

CERN Document Server

We discuss the octupole deformation properties of the recently proposed Barcelona-Catania-Paris (BCP) energy density functionals for two sets of isotopes, those of radium and barium, where it is believed that octupole deformation plays a role in the description of the ground state. The analysis is carried out in the mean field framework (Hartree- Fock- Bogoliubov approximation) by using the axially symmetric octupole moment as a constraint. The main ingredients entering the octupole collective Hamiltonian are evaluated and the lowest lying octupole eigenstates are obtained. In this way we restore, in an approximate way, the parity symmetry spontaneously broken by the mean field and also incorporate octupole fluctuations around the ground state solution. For each isotope the energy of the lowest lying $1^{-}$state and the $B(E1)$ and $B(E3)$ transition probabilities have been computed and compared to both the experimental data and the results obtained in the same framework with the Gogny D1S interaction, which...

Robledo, L M; Schuck, P; Viñas, X

2010-01-01

4

Octupole deformation properties of actinide isotopes within a mean field approach  

CERN Document Server

We discuss the octupole deformation properties of many even-even actinide isotopes. The analysis is carried out in the mean field framework (Hartree-Fock-Bogoliubov approximation) by using the axially symmetric octupole moment as a constraint. A one-dimensional octupole collective Hamiltonian is used to obtain properties like excitation energies or $E1$ and $E3$ transition probabilities of the negative parity band-heads associated to the lowest lying $1^{-}$ and $3^{-}$ states. The evolution of these values with neutron number is discussed and a comparison with available experimental data is made. In order to minimize the uncertainties associated to the energy density functional used, the calculations have been carried out for an assorted set ranging from the BCP1 functional to the finite range Gogny interaction with the D1S, D1N and D1M parametrization.

Robledo, L M; 10.1088/0954-3899/39/10/105103

2012-01-01

5

Octupole effects at super and normal deformation  

International Nuclear Information System (INIS)

This presentation deals with recent results on the onset of octupole collectivity in superdeformed nuclei of the A ? 190 and A ? 150 regions as well as in actinide nuclei at normal deformation. It is shown that most of the properties of these negative parity sequences can be understood in terms of Random Phase Approximation (RPA) calculations, although the observations in some Pu isotopes continue to be a challenge to interpret

6

Octupole Deformed Nuclei in the Actinide Region  

CERN Multimedia

% IS322 \\\\ \\\\ 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.

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

7

Experimental tests for stable octupole deformation in actinium-227  

International Nuclear Information System (INIS)

The question of intrinsic reflection asymmetry or stable-octupole deformation in 227Ac was studied by the single-proton stripping reactions 226Ra(3He,d)227Ac with E/sub 3He/ = 30 MeV and 226Ra(?,t)227Ac with E/sub ?/ = 30 MeV and by measuring the magnetic moment of the first excited 3/2+ state at 27.38 keV by a differential perturbed angular correlation (DPAC) experiment. Theoretical differential cross sections were determined using calculated nuclear structure factors with and without octupole-deformed Woods-Saxon model wave functions. Theoretical values for the magnetic moments of the ground state and first excited state with and without octupole deformation were determined using calculated intrinsic g-factors from folded Yukawa model wave functions. The results of the proton-stripping cross sections are inconclusive. No how comparison of the measured values for the magnetic moment of the first excited state with a previous measurement for the ground state seems to support stable octupole deformation in 227Ac. Therefore, the energy ordering of orbitals and the magnetic moment results are consistent and they seem to support a stable-octupole deformed shape for the ground state parity doublet in 227Ac. Furthermore, the results are consistent with the branching ratio determination of the magnetic moment of the first excited state in 227Ac which is in agreement with the stable-octupole model prediction

8

Quadrupole-octupole deformation in finite fermion system  

International Nuclear Information System (INIS)

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  

CERN Multimedia

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. \\...

2002-01-01

10

Fast nuclear rotation and octupole deformation  

CERN Document Server

The 150Sm nucleus has been studied to high spins in a measurement of gamma radiation following the 136Xe(18O,4n)150Sm, compound-nucleus reaction at beam energy of 76 MeV. The measurement was performed at NBI Riso using the NORDBALL array. Alternating parity, s=+1 band in 150Sm has been observed up to spin I=22. This band is crossed by two aligned bands, corresponding to a reflection-symmetric shape. After the second crossing the s=+1 band ends abruptly, suggesting that the octupole shape vanishes in 150Sm above spin I=22, as predicted by calculations. Other explanations, assuming continuation of the s=+1 band past the two alignments are also discussed.

Urban, W; Nyberg, J

2001-01-01

11

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

Science.gov (United States)

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.

Minkov, Nikolay; Walker, Phil

2014-05-01

12

Nuclear fusion as a probe for octupole deformation in $^{224}$Ra  

CERN Document Server

$\\textit{Background}$: Nuclear fusion has been shown to be a perfect probe to study the different nuclear shapes. However, the possibility of testing octupole deformation of a nucleus with this tool has not been fully explored yet. The presence of a stactic octupole deformation in nuclei will enhanced a possible permanent electric dipole moment, leading to a possible demonstration of parity violation. $\\textit{Purpose}$: To check whether static octupole deformation or octupole vibration in fusion give qualitatively different results so that both situations can be experimentally disentangled. $\\textit{Method}$: Fusion cross sections are computed in the Coupled-Channels formalism making use of the Ingoing-Wave Boundary Conditions (IWBC) for the systems $^{16}$O+$^{144}$Ba and $^{16}$O+$^{224}$Ra. $\\textit{Results}$: Barrier distributions of the two considered schemes show different patterns. For the $^{224}$Ra case, the octupole deformation parameter is large enough to create a sizeable difference. $\\textit{Con...

Kumar, Raj; Vitturi, A

2015-01-01

13

Signature splitting in octupole bands of vibrational and deformed nuclei  

International Nuclear Information System (INIS)

Energy staggering in negative-parity bands is studied in both vibrational and deformed regions. Good agreement is found between empirical signature patterns and those calculated in the IBA. It is shown that the calculations in each region depend essentially on only a single parameter. It is found that each kind of structural region displays unique and characteristic signature behaviour. In ?-soft [O(6)]nuclei the staggering is large and nearly independent of J. Octupole staggering can actually be used as a signature for this symmetry. In deformed regions, signature effects in K=1- bands show a striking singularity as a function of the filling of a shell, which, both experimentally and theoretically, is shown to be due to the crossing and mixing of K=0- and 1- bands. Finally, it is found that, albeit for different reasons in different structural regions, the signature splitting of low-lying negative-parity states in vibrational and deformed regions (K=1- bands) is almost always opposite in phase with that of positive-parity ?-bands: the only exception is at the very beginning of deformed regions. (orig.)

14

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

International Nuclear Information System (INIS)

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

15

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

International Nuclear Information System (INIS)

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.)

16

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

International Nuclear Information System (INIS)

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 (?0), 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 (?0), 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 ?0=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 ?2+?4/?2, 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 ?2 and ?3 as well as on the angular momentum. In the limit of a frozen ?2 the system oscillates between positive and negative octupole deformations by tunnelling through the barrier of the double-well potential in ?3. When ?2 is let to vary, the system oscillates between the positive and negative ?3-values by rounding the barrier in the (?2, ?3 )- 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

17

Quadrupole-octupole vibration-rotation model of deformed nuclei  

International Nuclear Information System (INIS)

Quadrupole and octupole surface excitations of axially symmetric nuclei and their interactions are studied. The collective wave function is constructed assuming that the interactions between these degrees of freedom are self-consistent. The basic characteristics of collective states (excitation energies, transition probabilities) are determined taking into account band interactions. The results are compared with experiment

18

Quadrupole-octupole rotation-vibration model of deformed nuclei  

International Nuclear Information System (INIS)

Quadrupole and octupole surface excitations of axial nuclei and relations between those excitations are studied. The collective wave function is built assuming that interaction between the above mentioned degrees of freedom is selfconsistent. The principal characteristics of collective states (excitation energies, transition probabilities) are determined taking into account interaction of bands. The results are compared to the experimental data

19

The rotational-vibration excited states of even-even nuclei with quadrupole and octupole deformations  

International Nuclear Information System (INIS)

On the basis of phenomenological collective theory the expression for energies of rotational-vibration excited states of even-even nuclei with quadrupole and octupole deformations are obtained. The values of energy are calculated for excited states of nuclei 150Sm, 154Dy, 218Ra, 222Th, 232U, 236U, 238U, including high spin states. (author)

20

Collective T- and P- odd electromagnetic moments in nuclei with octupole deformation  

International Nuclear Information System (INIS)

Parity and time invariance violating forces produce collective P- and T-odd moments in nuclei with static octupole deformation. Collective Schiff moment, electric octupole and dipole and also magnetic quadrupole appear due to the mixing of rotational levels of opposite parity and can exceed single-particle moments by more than a factor of 100. This enhancement is due to two factors, the collective nature of the intrinsic moments and the small energy separation between members of parity doublets. The above moments induce T- and P- odd effects in atoms and molecules. Experiments with such systems may improve substantially the limits on time reversal violation. (author)

21

Exotic octupole deformation in proton-rich Z=N nuclei  

Energy Technology Data Exchange (ETDEWEB)

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)

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

1998-03-01

22

Quadrupole deformed and octupole collective bands in {sup 228}Ra  

Energy Technology Data Exchange (ETDEWEB)

Spins and parities for collective states in {sup 228}Ra have been determined from conversion electron measurements with a mini-orange {beta} spectrometer. The fast-timing {beta}{gamma}{gamma}(t) method has been used to measure lifetimes of T{sub 1/2}=550(20) ps and 181(3) ps for the 2{sup +}{sub 1} and 4{sup +}{sub 1} members of the K=0{sup +} band, and T{sub 1/2}{<=}7 ps and {<=}6 ps for the 1{sup -}{sub 1} and 3{sup -}{sub 1} members of the K=0{sup -} band, respectively. The quadrupole moments, Q{sub 0}, deduced from the B(E2; 2{sup +}{sub 1}{yields}0{sup +}{sub 1}) and B(E2; 4{sup +}{sub 1}{yields}2{sup +}{sub 1}) rates are in good agreement with the previously measured value and the systematics of the region. However, the B(E1) rates of {>=}4 x 10{sup -4} e{sup 2} fm{sup 2}, which represent the first B(E1) measurements for this nucleus, are at least 25 times larger than the value previously suggested for {sup 228}Ra. The new results are consistent with the B(E1) rates recently measured for the neighbouring {sup 227}Ra and reveal octupole correlations in {sup 228}Ra. (orig.) 35 refs.

Gulda, K. [Warsaw Univ. (Poland). Inst. of Physics; Mach, H. [Department of Neutron Research, University of Uppsala, S-61182 Nykoeping (Sweden); Aas, A.J. [Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo (Norway)] [and others; ISOLDE Collaboration

1998-06-15

23

Competition between axial and non-axial octupole deformations in heavy nuclei  

International Nuclear Information System (INIS)

The macroscopic-microscopic method is applied to calculate the energies of heavy nuclei (A>220) in a multidimensional deformation space (??,?) including axial and non-axial quadrupole (?=2,?=0,2), axial and non-axial octupole (?=3,?=0,2) and axial hexadecapole (?=4,?=0) degrees of freedom. Shell and pairing corrections are calculated from the single-particle energies of the Woods-Saxon potential with the universal parameters and added to the macroscopic energy of the newest Lublin-Strasbourg Drop (LSD) model to obtain the total deformation energy. (author)

24

Prediction of octupole-deformation effects in superdeformed nuclei of A ? 150 and A ? 190 mass regions and possible interrelation with pseudo-spin symmetry  

International Nuclear Information System (INIS)

Stability with respect to axially symmetric but mirror-asymmetric distortions in superdeformed nuclei is analysed. Calculations based on the deformed Woods-Saxon potential and the cranking method together with the generalised Strutinsky approach indicate the existence of octupole-shape driving shell effects persisting up to the very high spin limit in superdeformed nuclei of both A ? 150 and A ? 190 mass regions. The strongest effects are predicted for Z ? 62-68 (combined with N ? 82-88) and for N ? 110-118 (combined with Z ? 80) particle numbers at quadrupole deformation ?2 ? 0.60 and ?2 ? 0.45, respectively. In both mass ranges the low lying octupole vibrations rather than the static octupole shapes are to be expected in most of the cases. The physical consequences of the above theoretical predictions are discussed in the context of the rotational bands based on the octupole oscillations and the symmetry properties of the decoupling parameter in the K=1/2 bands. (orig.)

25

Influence of octupole deformation and orientation on the potential energy surface in the di-nuclear system model  

International Nuclear Information System (INIS)

The nuclear and Coulomb potentials between deformed nuclei with octupole deformations and arbitrary orientations are evaluated numerically. The effects of the octupole deformation on the potential between nuclei and the potential energy surface (PES) used in the description of the production of super-heavy nuclei(SHN) by heavy-ion fusion reactions are investigated in the di-nuclear system model. It is found that the nuclear octupole deformation significantly changes the shape of the PES, which may influence the fusion probability of the SHN. Also, PESs in the tip-belly and belly-belly cases are investigated. Finally, the quasi-fission barriers in the tip-tip and belly-belly cases are evaluated. It is found that the quasi-fission barriers of the belly-belly case are generally larger than those of the tip-tip case. (authors)

26

? decay of 227Pa and 225Pa and octupole deformation in 223Ac  

International Nuclear Information System (INIS)

The level scheme of actinide nuclei with 130 ? N ? 140 and 85 ? Z ? 92 shows features originating from a reflection asymmetric intrinsic shape. In odd-mass nuclei this gives rise to parity doublets - pairs of levels with the same spin but opposite parity, having the same intrinsic structure - and enhanced E1 transition rates within these parity doublet bands. A summary of the experimental data can be found and models in terms of stable ground state octupole deformation, octupole vibrations, ? clustering and the interacting boson model have been developed. In this paper the authors report on an ?decay study of 227Pa and 225Pa populating levels in 223Ac and 221Ac. These nuclei are expected to show static quadrupole-octupole deformation. Using the LIGISOL facility the authors produced 227Pa via a (p,6n)-reaction on 223Th and 225Pa via a (p,6n)-reaction on 230Th. A number of experiments were performed in order to get level-scheme information. In case of 227Pa multiscaled ?-singles spectra (using PIPS detectors), (?, ?, t)- (?, X, t) coincidences (using a LEGe-type detector) and (?, e-, t) coincidences (using a cooled Si(li) detector) were taken. In addition, a fast timing setup of an ?-detector and a plastic or BaF2 scintillator was used to determine the halflife of 223Ac levels. In case of 225Pa only ?-singles spesup>Pa only ?-singles spectra were accumulated. The construction of a more complete level scheme compared to ref. 5 is in progress. Due to the short halflife of the E1 (65 keV) transition between the 5/2+ - 5/2- parity doublet, compared to the time resolution of the setup (about 840 ps), only an upper limit on its halflife has been set (t1/2 < 250 ps)

27

Exotic nuclear shapes - axial and nonaxial octupoles at normal and at super-deformation  

International Nuclear Information System (INIS)

Collective octupole dynamics have been studied including nonaxial components of the octupole mean field, mainly at superdeformed shape in the Hg-Pb region. Both the Strutinsky method combined with cranking and the generator coordinate method within the selfconsistent Hartree-Fock basis suggest the existence of collective octupole excitations at the superdeformed minima. GCM calculations point out to the E1 transitions as their most prominent experimental manifestation. The influence of the nonaxial octupole components on octupole dynamics in traditional octupole region of Ra-Th nuclei is also discussed. (authors) 38 refs., 6 figs., 1 tab

28

Vibration-rotation nuclear model with quadrupole-octupole deformations and self-consistent moments of inertia  

International Nuclear Information System (INIS)

Surface excitations of deformed and transition nuclei are studied without putting restrictions on the amplitudes of the static deformation. The moments of inertia and vibrational rigidities of excited states are evaluated in a self-consistent manner by solving the system of equations describing the quadrupole and octupole degrees of freedom coupled by rotations. For illustration we show the spectra of several hard and soft nuclei and compare with experimental data and with the results of other calculations

29

Self-consistent model of vibrational--rotational quadrupole--octupole excitations of deformed nuclei  

International Nuclear Information System (INIS)

For the unified description of collective states of both positive and negative parity a model is developed in which not only quadrupole but also octupole degrees of freedom are taken into account. The analysis is based on a self-consistent treatment of the interaction of the vibrational degrees of freedom through rotation of the nucleus. The model can be formulated in such a way that there is no expansion with respect to the ratio of the vibration amplitude to the static deformation, and therefore deformed as well as transitional nuclei, in which the static deformation may be small, can be studied in a unified manner. The moments of inertia and the vibrational rigidities are determined in a self-consistent manner and depend essentially on the angular momentum of the level. This has the consequence that with increasing angular momentum there is a rearrangement of the spectrum from a rotational to an equidistant spectrum. The possibility of an additional branch of the spectrum beginning at a certain value of the angular momentum is discussed. The corresponding collective states are treated as dynamical nonaxial isomers

30

Self-consistent model of vibrational rotational quadrupole-octupole excitations of deformed nuclei  

International Nuclear Information System (INIS)

A model for the unified description both of positive- and negative-parity collective states has been developed. Besides the quadrupole degrees of freedom, it also takes into account the octupole ones. The treatment is based on the consideration of a self-consistent nature of the interaction between the vibrational degrees of freedom via the rotation of nucleus. It is possible to formulate the model so that one can avoid the expansion in terms of the vibrational amplitude to the static deformation ratio. This allows one to extend the same method to the transitional nuclei where the static deformation can be small. The moments of inertia and vibrational rigidities are determined in a self-consistent way and essentially depend on angular momentum. This leads to the rearrangement of the rotational spectra to equidistant ones as the angular momentum increases. The possibility of an additional branch starting from some angular momentum value is discussed. The correspondingcollective states are interpreted as dynamic nonaxial isomers

31

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

CERN Multimedia

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.

32

Identification of excited states and evidence for octupole deformation in sup 2 sup 2 sup 6 U  

CERN Document Server

Excited yrast states in the neutron-deficient nucleus sup 2 sup 2 sup 6 U have been identified in two experiments performed at the Accelerator Laboratory of the University of Jyvaeskylae, Finland. In the first, the technique of recoil-decay tagging was employed using the JUROSPHERE plus RITU device, where the reaction channel of interest is selected through correlation with a characteristic decay. In the second, the RITU device was employed to study the alpha decay of sup 2 sup 3 sup 0 Pu. Through these experiments the level scheme of sup 2 sup 2 sup 6 U was deduced for the first time. Interleaved bands of positive- and negative- parity states suggest the octupole nature of this nucleus, and the behaviour of the difference in aligned angular momentum between the negative- and positive- parity states with rotational frequency is consistent with that expected of a rotating reflection-asymmetric shape. This represents an extension of the known octupole-deformed nuclei to Z = 92. The interleaved bands of alternat...

Greenlees, P T

1999-01-01

33

'Staggering' effect in even-even nuclei with quadrupole and octupole deformations  

International Nuclear Information System (INIS)

Full text: The odd-even staggering effect is known as a zigzagging behaviour of the nuclear inertial parameter between the odd and even angular momentum states of a rotational band. It is characterized by a relative displacement of the odd angular momentum levels with respect to the even ones. The analysis and the interpretation of this effect are of current interest since it carries detailed information about the fine structure of the nuclear collective spectrum in different regions of the nuclear chart. The odd-even staggering patterns can be determined as Stag(I)=6?E(I) - 4?E(I-1) - 4?E(I+1)+?E(I+2)+?E(I-2) here ?E(I)=E(I+1) - E(I), E(I)-energy levels [1], I-spin of the excited states of even-even nuclei. Stag (I) is very sensitive to the fine structure of rotational spectra and provides spectacular ?I=1 staggering patterns (zigzagging behaviour of the function Stag (I) with clearly defined zero reference) in various rotational bands. On this basis we propose a relevant theoretical analysis of the ?I=1 staggering effects in nuclear octupole bands in reference to the underlying reflection-asymmetric shape characteristics of the nuclear collective motion. The behaviour of the odd-even (?I=1) staggering effect in the nuclei 152,154Sm, 154,156,158Gd, 156Dy, 162,164Er, 228Th, 236,238U has been considered and shown that the odd-even staggering patterns do not vanish in the observed regio not vanish in the observed region of angular momentum. (author) Reference: 1. Sh. Sharipov, M. S. Nadirbekov, G. A. Yuldasheva Ukrainian Journal of Physics, 53,11(2008)

34

Informations on octupole correlations in light actinide nuclei  

International Nuclear Information System (INIS)

Experimental evidence for octupole correlations, which lead to octupole instability and octupole deformation of some nuclei, is illustrated through typical examples. Data are considered for the light actinide nuclei which have been studied up to moderately high spins. In case of 226Ra most of the electric dipole, quadrupole and, for the first time, octupole transition moments have been measured up to spin 18 for yrast states. (orig.)

35

Microscopic analysis of the octupole phase transition in Th isotopes  

CERN Document Server

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.

Nomura, K; Lu, B -N

2013-01-01

36

Extension of the multiphonon method to odd mass deformed nuclei. Pt. 2  

International Nuclear Information System (INIS)

The multiphonon method based on the collective K=0- octupole state is applied to the study of the low energy spectroscopic properties of 223-225-227Ac. Special attention is paid to various arguments usually invoked to assert that these isotopes have stable octupole deformation. A new criterium is proposed. (orig.)

37

Simultaneous quadrupole and octupole shape phase transitions in Thorium  

Energy Technology Data Exchange (ETDEWEB)

The evolution of quadrupole and octupole shapes in Th isotopes is studied in the framework of nuclear Density Functional Theory. Constrained energy maps and observables calculated with microscopic collective Hamiltonians indicate the occurrence of a simultaneous quantum shape phase transition between spherical and quadrupole-deformed prolate shapes, and between non-octupole and octupole-deformed shapes, as functions of the neutron number. The nucleus {sup 224}Th is closest to the critical point of a double phase transition. A microscopic mechanism of this phenomenon is discussed in terms of the evolution of single-nucleon orbitals with deformation.

Li, Z.P.; Song, B.Y.; Yao, J.M. [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Vretenar, D. [Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Meng, J., E-mail: mengj@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Department of Physics, University of Stellenbosch, Stellenbosch (South Africa)

2013-11-04

38

Microscopic analysis of the octupole phase transition in Th isotopes  

Science.gov (United States)

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 density dependent point coupling (DD-PC1) functional 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.

Nomura, K.; Vretenar, D.; Lu, B.-N.

2013-08-01

39

Electron scattering from the octupole band in /sup 238/U  

Energy Technology Data Exchange (ETDEWEB)

A simple model for nuclear surface vibrations in permanently deformed nuclei does well in reproducing electron scattering cross sections of rotational levels built on a K/sup ..pi../= 0/sup -/ intrinsic octupole vibration in /sup 238/U.

Hirsch, A.; Creswell, C.; Bertozzi, W.; Heisenberg, J.; Hynes, M.V.; Kowalski, S.; Miska, H.; Norum, B.; Rad, F.N.; Sargent, C.P.; Sasanuma, T.; Turchinetz, W.

1978-03-06

40

Electron scattering from the octupole band in 238U  

International Nuclear Information System (INIS)

A simple model for nuclear surface vibrations in permanently deformed nuclei does well in reproducing electron scattering cross sections of rotational levels built on a K/sup ?/= 0- intrinsic octupole vibration in 238U

41

Microscopic description of quadrupole-octupole coupling in Sm and Gd isotopes with the Gogny Energy Density Functional  

CERN Document Server

The interplay between the collective dynamics of the quadrupole and octupole deformation degree of freedom is discussed in a series of Sm and Gd isotopes both at the mean field level and beyond, including parity symmetry restoration and configuration mixing. Physical properties like negative parity excitation energies, E1 and E3 transition probabilities are discussed and compared to experimental data. Other relevant intrinsic quantities like dipole moments, ground state quadrupole moments or correlation energies associated to symmetry restoration and configuration mixing are discussed. For the considered isotopes, the quadrupole-octupole coupling is found to be weak and most of the properties of negative parity states can be described in terms of the octupole degree of freedom alone.

Rodriguez-Guzman, R; Sarriguren, P

2012-01-01

42

Baryon octupole moments  

OpenAIRE

We report on a calculation of higher electromagnetic multipole moments of baryons in a non-covariant quark model approach. The employed method is based on the underlying spin-flavor symmetry of the strong interaction and its breaking.We present results on magnetic octupole moments of decuplet baryons and discuss their implications.

Buchmann, A. J.; Henley, E. M.

2008-01-01

43

Magnetic moments of K isomers as indicators of octupole collectivity  

Energy Technology Data Exchange (ETDEWEB)

The relation between the quadrupole-octupole deformation and the structure of high-K isomers in heavy even-even nuclei is studied through a reflection asymmetric deformed shell model including a BCS procedure with constant pairing interaction. Two-quasiparticle states with K{sup {pi}} = 4 {sup -}, 5 {sup -}, 6 {sup -}, 6 {sup +} and 7 {sup -} are considered in the region of actinide nuclei (U, Pu and Cm) and rare-earth nuclei (Nd, Sm and Gd). The behaviour of two-quasiparticle energies and magnetic dipole moments of these configurations is examined over a wide range in the plane of quadrupole and octupole deformations ({beta}{sub 2} and {beta}{sub 3}). In all considered actinide nuclei, the calculations show that there is pronounced sensitivity of the magnetic moments to the octupole deformation. In the rare-earth nuclei, the calculations for {sup 154,} {sup 156}Gd show stronger sensitivity of the magnetic moment to the octupole deformation than in the other considered cases. (orig.)

Minkov, N. [Bulgarian Academy of Sciences, Institute of Nuclear Research and Nuclear Energy, Sofia (Bulgaria); University of Surrey, Department of Physics, Guildford (United Kingdom); Walker, P.M. [University of Surrey, Department of Physics, Guildford (United Kingdom); CERN, Geneva (Switzerland)

2012-06-15

44

Towards a unified collective model for the nuclear quadrupole and octupole modes  

International Nuclear Information System (INIS)

The original collective Hamiltonian is generalised to coupled multipole modes describing low-energy collective motion in nuclei. This Hamiltonian is applied to the quadrupole and octupole degrees of freedom coupled to each other. Methods for a numerical solution of the full problem are presented. The well known models of octupole excitations in spherical and strongly deformed nuclei are derived by means of the small-amplitude expansion around the equilibrium. A model of this kind is also derived for the case when a static octupole deformation occurs, which seems to be essential for nuclei in the Ra-Th region. (author)

45

Study on the nuclear transitions from the aligned states of the octupole bands in actinides as an example  

International Nuclear Information System (INIS)

A simple theoretical model designed for a qualitative analysis of octupole bonds in deformed nuclei (DN) under the conditions of heavy effect of the Coriolis forces is presented. The model is shown to be able to describe typical effects of the rotation bond and oscillation degrees of freedom both in the 0--band spectrum characteristics and in probabilities of E1 transtitions from them to the ground state band. The model allows one to follow changes in the nuclear state structure as aligning an angular momentum (AM). The octupole AM aligning is appreciable even in lower states of rotation bands with a negative parity in actinides. Selectivity of dipole transitions in the 232Th, sup(236, 238)U nuclei must be sufficiently pronounced even at spin I approximately 5 according to the above model. This conclusion corresponds to experimental data. Model conclusions on the effect of forming upon electrical nuclei properties are also confirmed by an experiments

46

Effects of octupole vibrations on quasiparticle modes of excitation in superdeformed 193Hg  

International Nuclear Information System (INIS)

A particle-vibration coupling calculation based on the RPA and the cranked shell model has been carried out for superdeformed rotational bands in 193Hg. The result suggests that properties of single-particle motions in superdeformed nuclei may be significantly affected by coupling effects with low-frequency octupole vibrational modes, especially by the lowest K = 2 octupole mode. (author)

47

Non-yrast quadrupole-octupole spectra  

Directory of Open Access Journals (Sweden)

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 ?-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.

Lenske H.

2012-12-01

48

Stable and Vibrational Octupole Modes in Mo, Xe, Ba, La, Ce and Nd  

Energy Technology Data Exchange (ETDEWEB)

Evidence is presented for stable octupole deformation in neutron-rich nuclei, bounded by Z = 54-58 and N = 85-92. To either side of this region negative parity bands built on more vibrational type octupole modes are observed in {sup 140}Ba and {sup 152,154}Nd. The largest stable octupole deformation ({beta}{sub s} {approximately} 0.1) is found in {sup 144}Ba{sub as}. The theoretically predicted quenching ({beta}{sub s} {approximately} 0) of stable octupole deformation at higher spins is found in {sup 140}Ba. There is good agreement between theory and experiment for the strongly varying electric dipole moments as a function of mass for {sup 142-141}Ba. In odd-A {sup 142}Ba and odd-Z {sup 140}La, we observe parity doublets, two pairs of positive and negative parity bands with opposite spins. In {sup 145}La a strong coupled ground band with symmetric shape coexists with the asymmetric octupole shape which stabilizes above about spin 19/2. In {sup 145,147}La a strong reduction in E2 strength around 25/2 from band crossing is observed. The isotope {sup 109}Mo was identified and a new region of stable uctpole deformation is identified in {sup 107,108}Mo centered around N = 64-66 as earlier predicted. This is the first case of stable uctpole deformation involving only one pair of orbitals.

Gore, P.M.; Hamilton, J.H.; Hwang, J.K.; Jones, E.F.; Peker, L.K.; Ramayya, A.V.; Zhang, X.Q.; Zhu, S.J.

1998-05-18

49

Stable and Vibrational Octupole Modes in Mo, Xe, Ba, La, Ce and Nd  

International Nuclear Information System (INIS)

Evidence is presented for stable octupole deformation in neutron-rich nuclei, bounded by Z = 54-58 and N = 85-92. To either side of this region negative parity bands built on more vibrational type octupole modes are observed in 140Ba and 152,154Nd. The largest stable octupole deformation (?s ? 0.1) is found in 144Baas. The theoretically predicted quenching (?s ? 0) of stable octupole deformation at higher spins is found in 140Ba. There is good agreement between theory and experiment for the strongly varying electric dipole moments as a function of mass for 142-141Ba. In odd-A 142Ba and odd-Z 140La, we observe parity doublets, two pairs of positive and negative parity bands with opposite spins. In 145La a strong coupled ground band with symmetric shape coexists with the asymmetric octupole shape which stabilizes above about spin 19/2. In 145,147La a strong reduction in E2 strength around 25/2 from band crossing is observed. The isotope 109Mo was identified and a new region of stable uctpole deformation is identified in 107,108Mo centered around N = 64-66 as earlier predicted. This is the first case of stable uctpole deformation involving only one pair of orbitals

50

The octupoles take pole position  

CERN Multimedia

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.

2002-01-01

51

On octupole alignment in actinides  

Science.gov (United States)

The alignment of the octupole angular momentum in the rotational states of the K? = 0- band is analysed in the microscopic model. The model describes qualitatively the branching ratio for the E1-transitions from these states to the ground band states. Permanent address: Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, F-91405 Orsay, France.

Nazmitdinov, R. G.; Mikhailov, I. N.; Briançon, Ch.

1987-04-01

52

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

CERN Multimedia

%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...

Hoff, P; Kaczarowski, R

2002-01-01

53

Octupole vibrational states in the even-mass barium isotopes  

International Nuclear Information System (INIS)

A low-lying state of 132Ba, 134Ba, 136Ba and 138Ba, strongly excited in the scattering of 20 MeV ? particles at 175 deg, is identified as the first 3- octupole vibrational state in each case. Angular distribution measurements for ? particle scattering to this state and the well known first 2+ state in 132Ba, 134Ba, 136Ba and 138Ba are in agreement with harmonic-vibration coupled-channels predictions. Deformation parameters are obtained, and the deduced isoscalar transition rates are compared with measured electromagnetic transition rates. The first 3- states of 132Ba, 134Ba, 136Ba and 138Ba are found to be at excitation energies of 2.070, 2.251, 2.529 and 2.879 MeV respectively. A state in 130Ba at an excitation energy of 1.948 MeV is tentatively identified as the first octupole-vibrational state in this nucleus

54

Investigation of octupole vibrational states in medium mass nuclei  

Energy Technology Data Exchange (ETDEWEB)

The experimental and theoretical evidence for the presence of octupole vibrational states in {sup 146}Sm and {sup 150}Nd is presented. The first nucleus which is located only two neutrons and two protons away from the N=82 shell and Z=64 subshell closures has been investigated by means of the {sup 143}Nd({alpha},n) and {sup 144}Nd({alpha},2n) fusion-evaporation reactions. The structure of the possible candidates for a 2{sup +} x 3{sup -} quadrupole-octupole multiplet are discussed in terms of the harmonic vibrational model and interpreted in terms of the Interacting Boson Approximation in the spdf boson space (IBA-spdf). The latter nucleus which is a quadrupole deformed nucleus was investigated via inelastic proton scattering which is an excellent method to excite natural parity states. Using this method, B(E1) ratios of the decaying transitions for the octupole vibrational states were determined and compared to the Alaga rule and with the IBA-spdf model. A general good agreement was found between experimental data and theoretical calculations.

Pascu, Sorin; Elvers, Michael; Endres, Janis; Hennig, Andreas; Pickstone, Simon; Zilges, Andreas [Institut fuer Kernphysik, Universitaet Koeln (Germany)

2012-07-01

55

Investigation of octupole vibrational states in medium mass nuclei  

International Nuclear Information System (INIS)

The experimental and theoretical evidence for the presence of octupole vibrational states in 146Sm and 150Nd is presented. The first nucleus which is located only two neutrons and two protons away from the N=82 shell and Z=64 subshell closures has been investigated by means of the 143Nd(?,n) and 144Nd(?,2n) fusion-evaporation reactions. The structure of the possible candidates for a 2+ x 3- quadrupole-octupole multiplet are discussed in terms of the harmonic vibrational model and interpreted in terms of the Interacting Boson Approximation in the spdf boson space (IBA-spdf). The latter nucleus which is a quadrupole deformed nucleus was investigated via inelastic proton scattering which is an excellent method to excite natural parity states. Using this method, B(E1) ratios of the decaying transitions for the octupole vibrational states were determined and compared to the Alaga rule and with the IBA-spdf model. A general good agreement was found between experimental data and theoretical calculations.

56

Observation of an octupole circle-times quasiparticle band in 175Lu using photon scattering experiments  

International Nuclear Information System (INIS)

A nuclear resonance fluorescence (NRF) study was performed on the heavy deformed nucleus 175Lu. We observe the beginning of a rotational band built on the coupling of the unpaired proton to the K?=0- octupole vibration in the neighboring nucleus 174Yb. The dipole strength distribution is also discussed in terms of the scissors mode. copyright 1997 The American Physical Society

57

Permanent deformation properties of asphalt concrete mixtures  

OpenAIRE

Rutting is recognized to be the major distress mechanism in flexible pavements as a result of increase in tire pressures and axle loads. Rutting is caused by the accumulation of permanent deformation in all or some of the layers in the pavement structure. The accumulation of permanent deformation in the asphalt surfacing layer is now recognized to be the major component of rutting in flexible pavements. This is a consequence of increased tire pressures and axle loads, which subjects the aspha...

Garba, Rabbira

2002-01-01

58

Mechanical Properties and Deformation Behavior of Bulk Metallic Glasses  

OpenAIRE

Metallic glasses demonstrate unique properties, including large elastic limit and high strength, which make them attractive for practical applications. Unlike crystalline alloys, metallic glasses, in general, do not exhibit a strain hardening effect, while plastic deformation at room temperature is localized in narrow shear bands. Room-temperature mechanical properties and deformation behavior of bulk metallic glassy samples and the crystal-glassy composites are reviewed in the present paper.

Alexander Yu. Churyumov; Louzguine-luzgin, Dmitri V.; Louzguina-luzgina, Larissa V.

2012-01-01

59

Nuclear collective motion with a coherent coupling interaction between quadrupole and octupole modes  

CERN Document Server

A collective Hamiltonian for the rotation-vibration motion of nuclei is considered, in which the axial quadrupole and octupole degrees of freedom are coupled through the centrifugal interaction. The potential of the system depends on the two deformation variables $\\beta_2$ and $\\beta_3$. The system is considered to oscillate between positive and negative $\\beta_3$-values, by rounding an infinite potential core in the $(\\beta_2,\\beta_3)$-plane with $\\beta_2>0$. By assuming a coherent contribution of the quadrupole and octupole oscillation modes in the collective motion, the energy spectrum is derived in an explicit analytic form, providing specific parity shift effects. On this basis several possible ways in the evolution of quadrupole-octupole collectivity are outlined. A particular application of the model to the energy levels and electric transition probabilities in alternating parity spectra of the nuclei $^{150}$Nd, $^{152}$Sm, $^{154}$Gd and $^{156}$Dy is presented.

Minkov, N; Drenska, S B; Scheid, W; Bonatsos, D; Lenis, D; Petrellis, D

2006-01-01

60

Microscopic description of octupole shape-phase transitions in light actinide and rare-earth nuclei  

Science.gov (United States)

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 ?2-?3 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 ?3-soft potentials.

Nomura, K.; Vretenar, D.; Nikši?, T.; Lu, Bing-Nan

2014-02-01

61

Quadrupole-octupole rotation-vibration model with self-consistent moments of inertia  

International Nuclear Information System (INIS)

Surface excitations of deformed and transitional nuclei are studied without imposing restrictions on the amplitudes of the static deformation. The moments of inertia and vibrational moduli of elasticity of the excited states are determined in a self-consistent way by solving the set of equations that describe the interaction of quadrupole and octupole degrees of freedom due to rotations. The calculated spectra of some rigid and soft nuclei are compared with the available experimental data and calculations by other methods. (orig.)

62

Corneal biomechanical properties from air-puff corneal deformation imaging  

Science.gov (United States)

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.

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

2014-02-01

63

Some properties of deformed q-numbers  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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 p [...] roduct 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.

Thierry C. Petit, Lobão; Pedro G. S., Cardoso; Suani T. R., Pinho; Ernesto P., Borges.

2009-08-01

64

Magnetic properties of single-domain powders after plastic deformation  

International Nuclear Information System (INIS)

Magnetic properties of fine-dispersed powders of nickel, fcc cobalt and Co-alloys containing 46 and 51 weight % have been investigated. Single-domain powder plastic deformation proved to lead to magnetic property changes in fcc and hcp transformation materials (nickel-Co). In isotropic samples residual magnetisation magnitude and powder coercitivity strength are decreasing, alongside with a shift of hysteresis frequent cycles along the axis of ordinates. In structural samples residual magnetisation anisotropy is increasing. It points to the uniaxial anisotropy appearing in particles. A crystal structure model of deformed particles is presented which provide magnetic uniaxiality

65

q-deformed noncommutative cat states and their nonclassical properties  

CERN Document Server

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.

Dey, Sanjib

2015-01-01

66

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

DEFF Research Database (Denmark)

The main goal of the study presented in this thesis was to perform in-situ investigations on deformation structures in plastically deformed polycrystalline copper at low degrees of tensile deformation (<5%). Copper is taken as a model system for cell forming pure fcc metals. Anovel synchrotron-radiation based technique High Angular Resolution 3DXRD has been developed at the 1-ID beam-line at the Advanced Photon Source. The technique extents the 3DXRD approach, to 3D reciprocal space mapping with a resolution of ? 1 · 10?3Å?1 and allows for in-situmapping of reflections from deeply-embedded individual grains in polycrystalline samples during tensile deformation. We have shown that the resulting 3D reciprocal space maps from tensile deformed copper comprise a pronounced structure, consisting of bright sharp peaks superimposed on a cloud of enhanced intensity. Based on the integrated intensity, the 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 load, focusing on grains that have the tensile direction close to the h100i direction. It was found that the individual subgrains, on average, are subjected to a reduction of the elastic strain with respect to the mean elastic strain of the grain. The walls are equivalently subjected to an increased elastic strain. The distribution of the elastic strains between the individual subgrains is found to be wider than the distribution of strains within the individual subgrains. The average properties are consistent with a composite type ofmodel. The details, however, show that present understanding of 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 a pre-deformed sample was performed, allowing for investigation of individual subgrains during straining. The result indicates that the cell refinement process generally does not take place through simple subgrain breakups. Surprisingly, the dislocation structure shows intermittent behavior, with subgrains appearing and disappearing with increasing strain, suggesting a dynamical development of the structure.

Jakobsen, Bo

2006-01-01

67

Deformation properties of the BCP energy density functional  

CERN Document Server

We explore the deformation properties of the newly postulated BCP energy density functional (EDF). The results obtained for three isotope chains of Mg, Dy and Ra are compared to the available experimental data as well as to the results of the Gogny-D1S force. Results for the fission barrier of $^{240}$Pu are also discussed.

Robledo, L M; Schuck, P; Viñas, X

2008-01-01

68

Mechanical deformation mechanisms and properties of amyloid fibrils.  

Science.gov (United States)

Amyloid fibrils have recently received attention due to their remarkable mechanical properties, which are highly correlated with their biological functions. We have studied the mechanical deformation mechanisms and properties of amyloid fibrils as a function of their length scales by using atomistic simulations. It is shown that the length of amyloid fibrils plays a role in their deformation and fracture mechanisms in such a way that the competition between shear and bending deformations is highly dependent on the fibril length, and that as the fibril length increases, so does the bending strength of the fibril while its shear strength decreases. The dependence of rupture force for amyloid fibrils on their length is elucidated using the Bell model, which suggests that the rupture force of the fibril is determined from the hydrogen bond rupture mechanism that critically depends on the fibril length. We have measured the toughness of amyloid fibrils, which is shown to depend on the fibril length. In particular, the toughness of the fibril with its length of ?3 nm is estimated to be ?30 kcal mol(-1) nm(-3), comparable to that of a spider silk crystal with its length of ?2 nm. Moreover, we have shown the important effect of the pulling rate on the mechanical deformation mechanisms and properties of amyloid fibril. It is found that as the pulling rate increases, so does the contribution of the shear effect to the elastic deformation of the amyloid fibril with its length of amyloid fibril with its length of >15 nm is almost independent of the pulling rate. Our study sheds light on the role of the length scale of amyloid fibrils and the pulling rate in their mechanical behaviors and properties, which may provide insights into how the excellent mechanical properties of protein fibrils can be determined. PMID:25426573

Choi, Bumjoon; Yoon, Gwonchan; Lee, Sang Woo; Eom, Kilho

2015-01-14

69

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

International Nuclear Information System (INIS)

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)

70

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

CERN Document Server

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...

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

2014-01-01

71

Deformation bands in porous sandstones their microstructure and petrophysical properties  

Energy Technology Data Exchange (ETDEWEB)

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 leng

Torabi, Anita

2007-12-15

72

On an isomonodromy deformation equation without the Painlevé property  

Science.gov (United States)

We show that the fourth-order nonlinear ODE which controls the pole dynamics in the general solution of equation P {I/2} compatible with the KdV equation exhibits two remarkable properties: (1) it governs the isomonodromy deformations of a 2 × 2 matrix linear ODE with polynomial coefficients, and (2) it does not possess the Painlevé property. We also study the properties of the Riemann-Hilbert problem associated to this ODE and find its large- t asymptotic solution for physically interesting initial data.

Dubrovin, B.; Kapaev, A.

2014-03-01

73

The electrochemical properties of the cyclic deformed passive metals  

International Nuclear Information System (INIS)

It has been investigated the influence of chloride environment on corrosion fatigue fracture of different classes stainless steels. The change of electrochemical properties of deformed corrosion resistance steels and alloys during the initial stage of corrosion fatigue fracture has been studied. It has been determined the influence of micro-deformation processes of surface at different tensions on the electrochemical activating of stainless steels. The critical values of electrochemical parameters of the deformed metal has been established, at which probability of corrosion fatigue fracture grows sharply. The features of character change polarization current of stainless steels at loadings even to corrosion fatigue limit has been shown. It served by basis for development of method speed-up determination of corrosion fatigue limit without destruction of specimens. It has been established possibility of decline corrosion currents of stainless steels as a result of deformation at tensions which do not cause destruction. It was revealed the reason of this effect: different acceleration by mechanical tensions of dissolution of alloys separate components, that results in enrichment of surface by a chrome and nickel. It is instrumental in the improvement of protective properties of passive tapes. The analysis of results of the conducted researches allowed to set that corrosion endurance of stainless steels is determined by intensity of their electrochemical activating at tensions of even to corrosive fatigue limit. (authors)

74

Neoclassical currents in the Wisconsin Levitated Octupole  

International Nuclear Information System (INIS)

Neoclassical transport theory predicts the existence of bootstrap current in collisionless plasmas with a significant population of trapped particles. This unidirectional current flows along field lines, and is generated by the balancing of ion-electron friction forces with the viscous forces between trapped and untrapped like particles. The current is driven by gradients in the plasma pressure and temperature. Previous work has identified the existence of bootstrap current in the Wisconsin Levitated Octupole, and this discovery of bootstrap current in the octupole naturally leads to the question of why previous experiments were unsuccessful in their endeavors to identify this current. The original motivation for this thesis was to address that question, by investigating the effects on bootstrap current caused by ohmic currents, plasma fluctuations, and rf fields. Ohmic currents, while naturally present in tokamaks, can be introduced in the octupole, independent of the usual operating procedure, and can be adjusted to be of the same order of magnitude as the expected diamagnetic and parallel currents. The interaction, if any, of bootstrap current and ohmic current can thus be determined without the problem of a large ohmic current masking the neoclassical current. Rf fields can be driven in the octupole plasma with little or no plasma heating. Any anomalous effects on the parallel currents, due to the existence of the rf fields, can then be determined. This thesis consists of four parts: the experimental apparatus and the plasma diagnostics used in these studies; the general theory of neoclassical currents (excluding field errors) and how it is applied to the octupole; the experimental results of this investigation; and a brief discussion of the conclusions that can be inferred from the data

75

Microstructure, properties and hot deformability of the new maraging steels  

Directory of Open Access Journals (Sweden)

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.

S.J. Pawlak

2008-07-01

76

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1995-08-01

77

Octupole bands and simplex inversion in the neutron-rich nucleus 145Ba  

Science.gov (United States)

The issue of the existence of reflection asymmetry in 145Ba has stood for the past 30 years without a common conclusion. The recent experimental data show a number of low-lying rotational bands with alternative parities, providing more strict constraints on the relevant modeling. With a proper octupole deformation, all the observed six rotational bands in 145Ba have been well reproduced by the reflection asymmetric shell model (RASM). The three octupole deformed neutron single-particle orbitals just above the octupole shell gap 88, with K =1 /2 ,K =3 /2 , and K =5 /2 , respectively, dominate the intrinsic configurations of the observed bands. Based on the analysis of the calculated RASM wave functions, the assignments for the observed bands have been given. The experimental yrast band (? I =1 ) presents a simplex inversion at around the 11 /2- state where the simplex staggering phase changes. This phenomenon may be explained in the framework of the RASM as from the change of the dominate intrinsic configuration, induced by the band mixing. The present results strongly support the appearance of the reflection asymmetry in the ground and low-lying states of 145Ba.

Chen, Yong-Jing; Gao, Zao-Chun; Chen, Yong-Shou; Tu, Ya

2015-01-01

78

Observation of octupoles states in the fission probability of different thorium isotopes  

International Nuclear Information System (INIS)

Sharp resonances are observed in the fission probability of 230Th, 231Th and 233Th, measured in the (n,f) and (d,pf) reactions below the fission threshold. A simultaneous analysis of these resonances and of the associated fission fragment angular distributions concludes to the presence of two superimposed bands of levels, with a very large moment of inertia. These levels are interpreted as the lower levels in the ''third well'', predicted by the calculations to occur, at large quadrupole deformation and non-vanishing octupole deformation, in the potential energy surface of the light actinides

79

Spin assignment of the lowest octupole bandhead in 236U  

International Nuclear Information System (INIS)

Measurements carried out to determine the nature of the octupole bandhead in 236U led in the past to considerable confusion concerning its spin assignment. To see whether penetration effects are important in the conversion electron decay of the octupole band, a high resolution measurement was carried out at the #betta#-spectrometer of the ILL. Relative intensities have been determined for the transitions from the octupole bandhead to the O+, 2+ and 4+ members of the ground state rotational. (U.K.)

80

Tooth and bone deformation: structure and material properties by ESPI  

Science.gov (United States)

In order to understand complex-hierarchical biomaterials such as bones and teeth, it is necessary to relate their structure and mechanical-properties. We have adapted electronic speckle pattern-correlation interferometry (ESPI) to make measurements of deformation of small water-immersed specimens of teeth and bones. By combining full-field ESPI with precision mechanical loading we mapped sub-micron displacements and determined material-properties of the samples. By gradually and elastically compressing the samples, we compensate for poor S/N-ratios and displacement differences of about 100nm were reliably determined along samples just 2~3mm long. We produced stress-strain curves well within the elastic performance range of these materials under biologically relevant conditions. For human tooth-dentin, Young's modulus in inter-dental areas of the root is 40% higher than on the outer sides. For cubic equine bone samples the compression modulus of axial orientations is about double the modulus of radial and tangential orientations (20 GPa versus 10 GPa respectively). Furthermore, we measured and reproduced a surprisingly low Poisson's ratio, which averaged about 0.1. Thus the non-contact and non-destructive measurements by ESPI produce high sensitivity analyses of mechanical properties of mineralized tissues. This paves the way for mapping deformation-differences of various regions of bones, teeth and other biomaterials.

Zaslansky, Paul; Shahar, Ron; Barak, Meir M.; Friesem, Asher A.; Weiner, Steve

2006-08-01

81

Effects of coupled structural and diagenetic processes on deformation localization and flow properties of deformation bands in sandstone  

Science.gov (United States)

Deformation bands tend to restrict flow perpendicular to the bands through the combined effects of porosity reduction, mechanical grain size reduction, and preferred cementation relative to the adjacent host rock. Thus, deformation bands may impart a permeability anisotropy to reservoir rocks. Deformation bands that occur in association with reservoir scale faults can impact reservoir-scale fluid flow and fault seal behavior. Using a combination of textural imaging including SEM-based cathodoluminescence imaging, compositional analysis, and lab petrophysics, this study is designed to (1) assess the effects of coupled chemical and mechanical processes leading to deformation localization in deformation bands and (2) to quantify the effect of these processes on single and multiphase fluid flow. While the effects of mechanical processes including grain translation, rotation, and breakage have been described in detail, chemical reactions affecting flow properties have received less attention. Such chemical reactions include the precipitation of carbonate and quartz cement, dissolution and albitization of feldspar, and the neoformation and infiltration of clay minerals. It is shown that the mechanical process of deformation localization is strongly controlled by chemical processes including pre-kinematic pore-filling cement, syn-kinematic cement filling intra- and transgranular fractures, and stress-enhanced dissolution reactions. Prekinematic cements reduce the strength contrast between grain and aggregate thus favoring deformation localization into narrow, well defined deformation bands. Prekinematic cementation and compaction may even favor thoroughgoing opening mode fractures and prevent localization of deformation into deformation band. Synkinematic cements within deformation bands will result in local strain hardening of bands and thus oppose further deformation localization with increasing strain. Examples will be presented from the Mesozoic clastic sequence of the western US to illustrate these processes.

Elliott, Sara; Eichhubl, Peter; Landry, Chris

2014-05-01

82

Low-lying octupole strength in 112Cd  

International Nuclear Information System (INIS)

The low-lying octupole strength distribution in 112Cd has been measured by means of inelastic proton scattering. A splitting of the strength has been observed and interpreted as due to the interaction between the quadrupole and octupole degrees of freedom. The splitting can be reproduced by the IBA-1 model if the coupling of f- and d-bosons is considered. (orig.)

83

Octupole modifications of the Clausius-Mossotti relation  

Science.gov (United States)

Numerical results are presented for the octupole polarizxability of closed p- and d-shell ions. The polarizabilities are used to determine the alterations form the dipole-octupole coupling to the Clausius-Mossotti relation for the dielectric function of ionic solids. Significant changes in the local field at the alkali atom site are found in the alkali-halides.

Mahan, G. D.

1980-02-01

84

Transient deformation properties of Zircaloy for LOCA simulation. Final report  

International Nuclear Information System (INIS)

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

85

Chiral symmetry restoration and pion properties in a q-deformed NJL model  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english We review the implementation of a q-deformed fermionic algebra in the Nambu-Jona-Lasinio model (NJL). The gap equations obtained from a deformed condensate as well as from the deformation of the NJL Hamiltonian are discussed. The effect of both temperature and deformation in the chiral symmetry rest [...] oration process as well as in the pion properties is studied.

V. S., Timóteo; C. L., Lima.

2006-03-01

86

Non-yrast quadrupole-octupole spectra  

OpenAIRE

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 ?-bands and higher negative-parity levels. In odd-mass nuclei the yrast levels are de...

Lenske H.; Strecker M.; Drumev K.; Minkov N.; Drenska S.; Scheid W.

2012-01-01

87

Magnetic-octupole order in neptunium dioxide?  

Science.gov (United States)

The phase transition occurring at 25 K in NpO2, discovered almost 50 years ago, is the most long-lasting mystery in the physics of actinide compounds. Theories based on magnetic or electric-quadrupole order lead inevitably to fundamental, qualitative inconsistencies with observations. We show that the phenomenology of NpO2 can be understood if the order parameter is assumed to be a magnetic octupole of gamma(2) ( xyz) symmetry. NpO2 is the first compound for which indications of an octupolar phase transition have been found. PMID:10970494

Santini; Amoretti

2000-09-01

88

Fluid and ionic transport properties of deformed salt rock  

International Nuclear Information System (INIS)

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

89

Indication of an octupole shape revealed in the (tau,?) population of high-spin states in 225Ra  

International Nuclear Information System (INIS)

High spin states in 225Ra have been populated in the (tau,?) reaction with a 30 MeV3 He beam. Levels associated with the jsub(15/2) intruder orbital are given special attention. The peculiar population pattern observed for such states, located at excitation energies of 274 and 538 keV in 225Ra, is predicted in a model calculation where an octupole deformation is assumed. (orig.)

90

Some electronic properties of metals through q-deformed algebras  

Science.gov (United States)

We study the thermodynamics of metals by applying q-deformed algebras. We shall mainly focus our attention on q-deformed Sommerfeld parameter as a function of q-deformed electronic specific heat. The results revealed that q-deformation acts as a factor of disorder or impurity, modifying the characteristics of a crystalline structure and thereby controlling the number of electrons per unit volume.

Tristant, Damien; Brito, Francisco A.

2014-08-01

91

Some Electronic Properties of Metals through q-Deformed Algebras  

CERN Document Server

We study the thermodynamics of metals by applying q-deformed algebras. We shall mainly focus our attention on q-deformed Sommerfeld parameter as function of q-deformed electronic specific heat. The results revealed that q-deformation acts as a factor of disorder or impurity, modifying the characteristics of a crystalline structure and thereby controlling the number of electrons per unit volume.

Tristant, Damien

2013-01-01

92

Octupole focusing in transport and accelerator systems  

International Nuclear Information System (INIS)

The radio-frequency quadrupole (RFQ) linac is capable of accelerating high-current, low-velocity ion beams. In accelerator systems comprising an RFQ and higher velocity accelerating structures, the current bottleneck still typically occurs within the RFQ. This limiting current is quite high in most cases, but linacs with even higher currents may be required in the future. We have begun a study of higher multipole systems to determine their capability or focusing and accelerating very high currents. We have chosen first to examine a radio-frequency octupole (RFQ) transport system, and have developed a smooth-approximation analytical description that includes the conditions for input radial matching of a zero space-charge beam. Further, we have constructed a multiparticle beam-dynamics simulation program that accepts the low-current matched beam and gradually increases the beam current as it is transported. This results in a matched high-current beam, and the procedure can be used to determine the saturation-current limit of a periodic octupole system. As expected, at high currents the beam develops a hollow radial distribution that reduces the space-charge defocusing; initial results show that high currents can be transported. For acceleration, we have formulated the design parameters for a section of RFQ linac, including the potential function, acceleration, and focusing efficiencies, and the geometry of the radially modulated pole tips

93

Effect of Degree of Deformation on the Mechanical Properties of High Temperature Thermomechanically Treated Steel  

OpenAIRE

The development of high strength materials, coupled with good formability, has always been the aim of material scientists. The effect of degree of deformation on the mechanical properties of high temperature themomechanically treated steel (HTMT) has been investigated in this study. It has shown that an increase in percent deformation results in improvement in mechanical properties. In order to have maximum strengthening, heavy deformation and low finishing temperature should be chosen.

Omotoyinbo, J. A.; Olorunniwo, O. E.; Ogundare, O.; Oluwole, O. O.

2006-01-01

94

Influence of Plastic Deformation on the Properties of 6066 Heat Treatable Aluminum Alloys  

OpenAIRE

The aims of this work are to (1) study the influence of plastic deformation on the properties of 6066 aluminum alloy; (2) study the effect of deformation on the age hardening of these alloys; (3) study the recovery of these defects from the samples. These effects were investigated in terms of microstructure using positron annihilation spectroscopy (PAS) analysis and mechanical properties by hardness measurements. Dislocations facilitate nucleation of precipitates. At first sight, deformed spe...

Badawi, Emad Abdelraouf; Abdel-naser, Mmdouh; Ahmed, Alaa Aldeen

2013-01-01

95

Photoelectron angular distribution parameters in the octupole approximation  

International Nuclear Information System (INIS)

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%

96

Large ferroquadrupole moment induced in the octupole-ordered Ce0.7La0.3B6 revealed by high-resolution x-ray diffraction  

Science.gov (United States)

We carried out a high-resolution x-ray diffraction experiment on Ce0.7La0.3B6 that exhibits staggered order of 4f octupole moments below TO=1.4 K. Theoretically, ferroquadrupole moments that accompany the antiferro-octupole order and a resultant rhombohedral deformation of the cubic lattice were predicted. In contrast, experimentally, no direct evidence of the rhombohedral lattice has been obtained. We observe the splitting of Bragg peaks below TO and find that the unit cell is a rhombohedron being elongated along the [111] axis. The response of rhombohedral domains to magnetic fields also well agrees with theoretical calculations. A particular outcome of this experiment is that the magnitude of the induced quadrupole moments is precisely evaluated from the obtained shear strain. Using this result, the magnitude of the hidden octupole moments is also discussed.

Inami, T.; Michimura, S.; Hayashi, Y.; Matsumura, T.; Sera, M.; Iga, F.

2014-07-01

97

On the octupole excitation in 236U  

International Nuclear Information System (INIS)

Measurements of the K, Lsub(I), Lsub(II) and Msub(I) conversion lines of the 687.7 keV transition in 236U are evaluated within the electron penetration formalism. The spin-parity assignment of the octupole-band-head is found to be 1- in accordance with reaction data, and an assignment of 2- to the 687.7 keV state is ruled out. The penetration matrix element vertical strokeetavertical stroke has the value of 13.5 for the K-shell and increases slightly for higher main shells. An estimate of the anomalous amplitudes is compared with values reported for transitions in the odd even actinide nuclei. Furthermore electron conversion data for the 1-->2+ and 1-->4+ transitions are given. Radioactivity 236U from 235U(n,e-); measured: conversion electron decay; deduced: conversion coefficients from K, L and M shells; evaluated: dynamic matrix elements. (orig.)

98

Influence of Plastic Deformation on the Properties of 6066 Heat Treatable Aluminum Alloys  

Directory of Open Access Journals (Sweden)

Full Text Available The aims of this work are to (1 study the influence of plastic deformation on the properties of 6066 aluminum alloy; (2 study the effect of deformation on the age hardening of these alloys; (3 study the recovery of these defects from the samples. These effects were investigated in terms of microstructure using positron annihilation spectroscopy (PAS analysis and mechanical properties by hardness measurements. Dislocations facilitate nucleation of precipitates. At first sight, deformed specimens had lower hardness as compared to non-deformed ones, and as the deformation increase, the hardness decreases. Another output of the mechanical test was the increase in hardness in the specimens after artificial aging with an increase in percent deformation.

Emad Abdelraouf BADAWI

2013-06-01

99

Effect of combined deformation on the structure and properties of copper and titanium alloys  

Science.gov (United States)

The effect of a combination scheme of severe plastic deformation and subsequent cold rolling or electroplastic rolling on the deformability, microstructural evolution, and mechanical properties of copper, titanium of various purities, and a titanium alloy of an equiatomic composition is studied. The combined deformation method is shown to create a number of new nanostructured and ultrafine-grained states with a high strength and ductility.

Stolyarov, V. V.; Pashinskaya, E. G.; Beigel'Zimer, Ya. E.

2010-10-01

100

Convergence properties of the q-deformed binomial distribution  

OpenAIRE

We consider the $q$-deformed binomial distribution introduced by{sc S. C. Jing:} {it The {$q$}-deformed binomial distribution and its asymptotic behaviour,}J. Phys. A {f 27} (2) (1994), 493--499and{sc W. S. Chung} et al: {it {$q$}-deformed probability and binomial distribution,} Internat. J. Theoret. Phys.{f 34} (11) (1995), 2165--2170and establish several convergence results involvingthe Euler and the exponential distribution; some of them are $q$-analogues of classical results.

Martin Zeiner

2010-01-01

101

String field theory. Algebraic structure, deformation properties and superstrings  

Energy Technology Data Exchange (ETDEWEB)

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.

Muenster, Korbinian

2013-07-23

102

String field theory. Algebraic structure, deformation properties and superstrings  

International Nuclear Information System (INIS)

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.

103

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

Science.gov (United States)

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 ?' 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.

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

2014-01-01

104

Influences of cyclic deformation on creep property and creep-fatigue life prediction considering them  

International Nuclear Information System (INIS)

Evaluation of creep-fatigue is essential in design and life management of high-temperature components in power generation plants. Cyclic deformation may alter creep property of the materials and its consideration may improve predictability of creep-fatigue failure life. To understand them, creep tests were conducted for the materials subjected to cyclic loading and their creep rupture and deformation behaviors were compared with those of as-received materials. Both 316FR and modified 9Cr-1Mo steel were tested. (1) Creep rupture time and elongation generally tend to decrease with cyclic loading in both materials, and especially elongation of 316FR drastically decreases by being cyclically deformed. (2) Amount of primary creep deformation decreases by cyclic loading and the ways to improve its predictability were developed. (3) Use of creep rupture ductility after cyclic deformation, instead of that of as-received material, brought about clear improvement of life prediction in a modified ductility exhaustion approach. (author)

105

Mechanical properties of hot deformed Inconel 718 and X750  

OpenAIRE

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 (720-1150°C) usin...

Nowotnik, A.; Pe?drak, P.; Sieniawski, J.; Go?ral, M.

2012-01-01

106

A study of plastic deformation during axisymmetric forward spiral extrusion and its subsequent mechanical property changes  

International Nuclear Information System (INIS)

Axisymmetric forward spiral extrusion (AFSE) accumulates large strains in its sample while extruding it through a die with engraved spiral grooves. A three-dimensional finite element model of AFSE has been developed using ABAQUS to investigate the deformation mode in detail, including the effect of groove geometry and the heterogeneity of plastic deformation. The numerical results demonstrated that the strain distribution in the AFSE sample cross section is linear in the radial direction within a concentric core while the distribution, outside the core, in the vicinity of the grooves is non-linear and non-axisymmetric. Mechanical properties and grain structure changes of the deformed sample were investigated. Improvements of mechanical properties in the processed samples can be attributed to the domination of the shear deformation mode in a plane normal to the extrusion axis and consequently the elongation of grains in the tangential direction. (paper)

107

Ground state octupole correlation energies with effective forces  

CERN Document Server

The ground state octupole correlations energies obtained with the D1M variant of the Gogny force are analyzed in detail. First we consider the correlation energy gained at the mean field level by allowing reflection symmetry breaking. Next we consider the energy gain coming from symmetry (parity) restoration and finally we analyze the ground state correlation energy after configuration mixing with axially symmetric octupole states. We find that these correlations do not significantly affect the trends of binding energies and systematics near closed shells. In particular, the too-large shell gaps predicted by self-consistent mean field models are not altered by the correlations.

Robledo, Luis M

2014-01-01

108

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 strength (Rm, flow limit (Rp0,2 and elongation (A in the function of annealing temperatures and annealing time at a constant deformation degree.

Trumi? B.

2010-01-01

109

Tailoring dislocation structures and mechanical properties of nanostructured metals produced by plastic deformation  

DEFF Research Database (Denmark)

The presence of a dislocation structure associated with low-angle dislocation boundaries and interior dislocations is a common and characteristic feature in nanostructured metals produced by plastic deformation, and plays an important role in determining both the strength and ductility of the nanostructured metals. The dislocation structure can be modified by post-process annealing and deformation which points to new ways of optimizing the mechanical properties. Such ways are demonstrated and discussed

Huang, Xiaoxu

2009-01-01

110

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

OpenAIRE

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 pres...

Saarna, Mart; Kommel, Igor; Traksmaa, Rainer; Kommel, Lembit

2012-01-01

111

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

OpenAIRE

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...

Trumi? B.; Stankovi? D.; Ivanovi? A.

2010-01-01

112

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

International Nuclear Information System (INIS)

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)

113

Effect of severe plastic deformation mode on microstructure and mechanical properties of AM60 magnesium alloy  

International Nuclear Information System (INIS)

Investigation results are reported for microstructure and mechanical properties of a magnesium base alloy AM60 (Mg-6 mas.% Al-0.13 mas.%Mn) subjected to severe plastic deformation (SPD). A consideration is given to microstructure evolution on heating specimens produced by equal channel angular pressing and torsional deformation. The results of tensile testing at room and elevated temperatures are presented for specimens after SPD

114

Fission fragment formation and fission yields in the model of octupole neutron-proton oscillations  

Directory of Open Access Journals (Sweden)

Full Text Available The fission fragment formation is considered as a result of neck instability in the process of octupole oscillations of neutrons and protons near the scission point. To describe such a phenomenon the potential surface of fissionning nucleus with neck radius about 1 fm was calculated with shell correction approach. The new version of smooth liquid drop part of deformation energy is proposed. The liquid drop part is formulated in a double folding model with n-n, p-p, and n-p Yukawa interaction potential. Fission fragment mass and charge distributions correspond approximately to isoscalar and isovector modes of vibrations and are defined by wave functions of oscillations. The preliminary calculation results have shown a rather good description of main integral fission yield observables.

Yavshits S.

2010-03-01

115

Determination of the deformation properties of Søvind Marl  

DEFF Research Database (Denmark)

A serie of tests were made to determine the preconsolidation stresses, ??pc, and the consolidation modulus, K, of Søvind Marl, a fissured plastic tertiary clay. The fissures causes a decrease in the stiffness of the Søvind Marl, which can be mistaken for the decrease that happens when the effective stresses in the soil, ??, passes ??pc. The effects of the fissures are assessed, and an estimate of the stress level at which they will compress are made. During the consolidation tests, the effective stress level is raised to more then 24,000 kPa to get a comprehensive description of the preconsolidation of the soil. It is important to know how a strongly preconsolidated soil will deform when reloaded. The deformation parameters of the strongly preconlidated Søvind Marl is determined by unloading/reloading testing. It is found that the stiffness of the Søvind Marl depends of the plasticity index, and one conclusive expression of the consolidation modulus of the Søvind Marl can therefor not be given.

GrØnbech, Gitte; Nielsen, Benjaminn Nordahl

2010-01-01

116

Cyclic deformation and dynamic compressive properties of copper bicrystals  

Energy Technology Data Exchange (ETDEWEB)

Cyclic deformation and dynamic compressive tests of three copper bicrystals were carried out on a Shimadzu servo-hydraulic testing machine and a split Hopkinson pressure bar (SHPB) apparatus respectively. The post-deformation dislocation structures, grain boundary (GB) serrations and adiabatic shear bands (ASBs) were examined using electron channeling contrast (ECC) imaging in a scanning electron microscope (SEM). After cyclic straining the secondary slip bands were activated near the GB forming a GB affected zone (GBAZ). Microstructures beneath it are dislocation labyrinth or irregular persistent slip bands (PSBs). The saturation stress at GBAZ was calculated to be higher than that in the grain interior. In dynamic compression, the formation of ASBs, was found to be promoted by the GB. Dynamic stress-strain curves were compared with each other for single crystals, bicrystals and polycrystals. Microstructures were also characterized with orientation imaging microscopy (OIM) by electron backscattering diffraction (EBSD) technique. It was found that relatively larger lattice rotations occurred across the ASBs than in the other regions, which can be deduced by the localization of simple shear along ASBs. No recrystallization was found in the ASBs or along GBs in the present circumstance.

Yang, R.Q. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)], E-mail: rqyang@imr.ac.cn; Li, S.X.; Zhang, Z.F. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

2007-09-25

117

Alternating parity bands and octupole effects in 221Th and 223Th  

International Nuclear Information System (INIS)

Level structures of the two neutron deficient odd-A nuclei 221Th and 223Th have been investigated by means of the reactions 208Pb(16O,3n)221Th and 208Pb(18O,3n)223Th. In-beam conversion electron and ?-ray spectroscopy in coincidence with the recoiling evaporation residues (R) has been carried out, including ??R-, e-?R- and e-e-R-coincidence measurements, as well as the determination of ?-ray angular distributions and ?-ray multiplicities using the NaI crystal ball. Level schemes could be established up to 13 ? above the ground state in 221Th and up to 33/2+ in 223Th. In 221Th one band of alternating parity states is observed, whereas in 223Th two such bands with equal intensity are seen. The level schemes are interpreted in terms of an octupole deformed core with an unpaired nucleon. From the E1/E2 branching ratio the electric dipole moments can be deduced; for 221Th one finds vertical strokeanti D0vertical stroke = 0.33±0.06 e.fm and for 223Thvertical strokeanti D0vertical stroke = 0.44±0.09 e.fm, the largest value observed so far in this mass region. The alignments of the different bands in 223Th with simplex quantum number s=±i are approximately equal and amount to = 3.7±0.3 for the positive-parity bands, a value which is in accord w, a value which is in accord with cranking calculations which assume octupole deformation. (orig.)

118

A Heisenberg ferromagnet with biquadratic and dipol-octupol interactions  

International Nuclear Information System (INIS)

A Heisenberg S = 3/2 ferromagnet with isotropic biquadratic exchange and dipole-octupol coupling is discussed. The conditions for the exact ferromagnetic ground state are derived. The thermodynamical behaviour in the molecular field approximation is discussed. Collective excitation spectra and the 1/z correction to the free energy are found. (orig.)

119

Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions  

International Nuclear Information System (INIS)

We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is ?150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrast to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion–He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species

120

Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions  

Energy Technology Data Exchange (ETDEWEB)

We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is ?150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrast to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion–He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species.

Boyarkin, Oleg V., E-mail: oleg.boiarkin@epfl.ch; Kopysov, Vladimir [Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne (Switzerland)

2014-03-15

121

Microstructures and Mechanical Properties of High-Mn TRIP Steel Based on Warm Deformation of Martensite  

Science.gov (United States)

High-Mn TRIP steel with about 5 wt pct Mn was prepared by a thermo-mechanical treatment based on warm deformation of martensite and subsequent short-time annealing in the intercritical region. The microstructural evolution and the mechanical properties of the used steel during such treatment were investigated. The results indicate that during warm deformation of martensite in the intercritical region, the decomposition of martensite was accelerated by warm deformation and the occurrence of dynamic recrystallization of ferrite led to the formation of equiaxed ferrite grains. Meanwhile, the reverse transformation of austenite was accelerated by warm deformation to some extent. During subsequent annealing in the intercritical region, static recrystallization of ferrite led to the increase in the fraction of equiaxed ferrite grains, and the formation of the reversed austenite was accelerated by the addition of the deformation-stored energy, while the stability of the reversed austenite was improved by the accelerated diffusions of C atoms and Mn atoms. As a whole, the mechanical properties of the used steel by the thermo-mechanical treatment based on warm deformation of martensite and subsequent short-time annealing in the intercritical region were comparable to the steels with similar compositions subjected to intercritical annealing for hours after cold rolling of martensite.

Guo, Zhikai; Li, Longfei; Yang, Wangyue; Sun, Zuqing

2015-01-01

122

Measurement of tune spread in the Tevatron versus octupole strength  

International Nuclear Information System (INIS)

A experiment was performed in the Tevatron to measure the tune spread versus octupole strength. The experiment is sensitive to the relationship between octupole strength and current in the T:OZF circuit and to the octupole (and other non-linear focusing fields) in the Tevatron. The major motivation for the experiment was to determine the value of octupole excitation that minimizes the tune spread: this value is an estimate of the value required to obtain ''zero'' total octupole excitation in the extraction process. The experiment was performed using the strip-line kickers at A17 and the resonant Schottky pickups. The horizontal proton kicker was excited with a sine-wave from a vector signal analyzer (HP-89440A) and the horizontal proton signal was received. The gating circuitry normally used to select proton or antiproton bunches was by-passed. The response function was measured and recorded on a floppy disk. Measurements were initially made with a 200 Hz span (0.250 Hz frequency bins) and later with a 100 Hz span (0.125 Hz frequency bins). The data was all obtained at flattop (800 GeV) with Q39S and Q39C set to correct the 1/2 integer stop band and QXR (the extraction regulation system) turned off. No attempt was made to examine sensitivity to closed orbit, chromaticity, or any other machine parameters other than the zero harmonic octupoles. The tune varied slightly (presumably because of feed-down effects from the octupoles), but was approximately constant at 19.472, but was approximately constant at 19.472 (only the fractional part was measured). The beam emittance was not measured because the flying wires were not working when these data were taken. The analysis of the data was accomplished by replotting the data from the floppy disk. The peak amplitude and the full width at 25% of the peak height were measured. Figures 1-7 show some of the data that was obtained. The vertical scales in figures 1-7 are adjusted so that the data span 80% of the full height of the screen. The hardware requires the markers to be measured points, so the width measured is not exactly at 25% of full height

123

Effect of material property heterogeneity on biomechanical modeling of prostate under deformation  

Science.gov (United States)

Biomechanical model based deformable image registration has been widely used to account for prostate deformation in various medical imaging procedures. Biomechanical material properties are important components of a biomechanical model. In this study, the effect of incorporating tumor-specific material properties in the prostate biomechanical model was investigated to provide insight into the potential impact of material heterogeneity on the prostate deformation calculations. First, a simple spherical prostate and tumor model was used to analytically describe the deformations and demonstrate the fundamental effect of changes in the tumor volume and stiffness in the modeled deformation. Next, using a clinical prostate model, a parametric approach was used to describe the variations in the heterogeneous prostate model by changing tumor volume, stiffness, and location, to show the differences in the modeled deformation between heterogeneous and homogeneous prostate models. Finally, five clinical prostatectomy examples were used in separately performed homogeneous and heterogeneous biomechanical model based registrations to describe the deformations between 3D reconstructed histopathology images and ex vivo magnetic resonance imaging, and examine the potential clinical impact of modeling biomechanical heterogeneity of the prostate. The analytical formulation showed that increasing the tumor volume and stiffness could significantly increase the impact of the heterogeneous prostate model in the calculated displacement differences compared to the homogeneous model. The parametric approach using a single prostate model indicated up to 4.8?mm of displacement difference at the tumor boundary compared to a homogeneous model. Such differences in the deformation of the prostate could be potentially clinically significant given the voxel size of the ex vivo MR images (0.3? × ?0.3? × ?0.3?mm). However, no significant changes in the registration accuracy were observed using heterogeneous models for the limited number of clinical prostatectomy patients modeled and evaluated in this study.

Samavati, Navid; McGrath, Deirdre M.; Jewett, Michael A. S.; van der Kwast, Theo; Ménard, Cynthia; Brock, Kristy K.

2015-01-01

124

Large-Deformation Properties of Wheat Flour and Gluten Dough  

OpenAIRE

Keywords: Wheat, gluten protein, bread, puff pastry, flour dough, gluten dough,rheology,uniaxialextension, biaxial extension, fracture.Rheologicaland fracture properties of flour and glutendoughsfrom eight wheat cultivars were studied and related to ...

Sliwinski, E. L.

2003-01-01

125

Mechanical properties and deformation of polycrystalline lithium orthosilicate  

International Nuclear Information System (INIS)

Room-temperature strength, fracture toughness, Young's modulus, and thermal-shock resistance were determined for 68--98% dense lithium orthosilicate (Li4SiO4) specimens. In the low-density regime, both strength and fracture toughness were controlled by the density of the specimen. At high density, the strength depends on grain size. Young's modulus values ranged from 30--103 GPa at densities between 68 and 98% TD. A critical quenching temperature difference in the range of 150--170/degree/C was observed in thermal-shock tests of bar specimens. Steady-state creep tests indicated 90% dense Li4SiO4 fractures at T ? 800/degree/C before reaching steady state and deforms plastically at 900/degree/C. It is more creep-resistant at 900/degree/C than Li2O, about equal to Li2Zr)3, and less than LiA102. 13 refs., 4 figs., 1 tab

126

Homogenized Elastic Properties of Graphene for Small Deformations  

Directory of Open Access Journals (Sweden)

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.

Jurica Sori?

2013-09-01

127

Self-Similarity Properties of Nafionized and Filtered Water and Deformed Coherent States  

Science.gov (United States)

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.

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

2014-11-01

128

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

OpenAIRE

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.

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

2013-01-01

129

Deformation properties of the Barcelona-Catania-Paris (BCP) energy density functional  

International Nuclear Information System (INIS)

We explore the deformation properties of the newly postulated Barcelona-Catania-Paris (BCP) energy density functional (EDF). The results obtained for three isotope chains of Mg, Dy, and Ra are compared to the available experimental data as well as to the results of the Gogny-D1S force. Results for the fission barrier of 240Pu are also discussed

130

PROPERTIES AND NANOSTRUCTURES OF NANO-MATERIALS PROCESSED BY SEVERE PLASTIC DEFORMATION (SPD).  

Energy Technology Data Exchange (ETDEWEB)

Metallic materials usually exhibit higher strength but lower ductility after being plastically deformed by conventional techniques such as rolling, drawing and extrusion. In contrast, nanostructured metals and alloys processed by severe plastic deformation (SPD) have demonstrated both high strength and high ductility. This extraordinary mechanical behavior is attributed to the unique nanostructures generated by SPD processing. The combination of ultrafine grain size and high-density dislocations appears to enable deformation by new mechanisms not active in coarse-grained metals and alloys. These results demonstrate the possibility of tailoring the microstructures of metals and alloys by SPD to obtain superior mechanical properties. Nanostructured metals and alloys processed by SPD techniques have unique nanostructures not observed in nanomaterials synthesized by other techniques such as the consolidation of nanopowders. The SPD-generated nanostructures have many features related to deformation, including high dislocation densities, and high- and low-angle grain boundaries in equilibrium or nonequilibrium states. Future studies are needed to investigate the deformation mechanisms that relate the unique nanostructures with the superior mechanical properties exhibited by SPD-processed metals and alloys.

Zhu, Y. T. (Yuntian Theodore)

2001-01-01

131

Influence of grain shape and orientation on the mechanical properties of high pressure torsion deformed nickel  

OpenAIRE

Severely plastically deformed (SPD) materials, for example those produced by high pressure torsion (HPT), are reported to possess outstanding mechanical properties. A typical HPT microstructure consists of elongated grains, usually of grain size well below 1 ?m, which are aligned parallel to the shear plane and showing typical shear texture components. To answer the question of how these single features of a SPD microstructure affect the mechanical properties individually, such as the yield...

Rathmayr, Georg B.; Hohenwarter, Anton; Pippan, Reinhard

2013-01-01

132

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.

Alexander I. Khaimovich

2014-10-01

133

Effects of deformation rates on mechanical properties of PP/SEBS blends  

OpenAIRE

Purpose: The goal of this study is to examine effects of tensile deformation rates ( ) on tensile properties of polypropylene/poly(styrene-b-ethylene-co-butylene-b-styrene) copolymer (PP/SEBS) blends and to determine suitable for accurate and reliable evaluation of mechanical properties of the blends in accordance with the results of Izod impact tests.Design/methodology/approach: PP/SEBS blends containing ?e = 0, 2.5, 5 and 10 volume % of SEBS thermoplastic elastomer were compounded using...

Balkan, O.; Demirer, H.; Sabri Kayal?, E.

2011-01-01

134

Using octupoles for background control in linear colliders -- An exploratory conceptual study  

International Nuclear Information System (INIS)

If one adds a suited Octupole (or an even higher multipole) lattice to linear collider Quadrupole FODO lattices, the amplifying properties of the combined lattice drive particles in the tails, but not those in the core, into resonant losses. This approach is quite different in concept and beam dynamics impact from past proposed use of non-linear elements for collimation. This non-traditional scheme for background control has the added advantage that most, or maybe all, of the Halo collimation can be done using the lever arm of the real estate of the main accelerators, thus reducing the costly length of a separate dedicated collimation section and also unifying machine protection and background control. Simulations of particle distributions are presented. This approach requires cooperation by the designers of the accelerators, the beam delivery system, and the Detector, because a careful balance between sometimes conflicting requirements has to be found. As a second component of this approach the use of Octupoles right before the final focusing Quadrupoles is proposed in order to enlarge the effective beam stay clear by a factor of 2--3, thus reducing the requirements for collimation. This concept would reduce the requirement for collimation but simulation have not been carried out here in detail. To further explore and implement this concept will require a considerable effort in manpower, possibly comparable to, although less in scope, than the effort to develop the Nin scope, than the effort to develop the NLC RF or the CLIC RF schemes

135

Neutron-Rich Nuclei Beyond 132Sn: Spherical Shapes and Octupole Correlations  

International Nuclear Information System (INIS)

Nuclear properties of nuclei with a few valence nucleons outside the doubly-magic 132Sn core and located in the octupole correlation region have been investigated via ?-?-? coincidence measurements of prompt gamma-ray emitted in the spontaneous fission of 252Cf with Gammasphere. The high spin level scheme of 134I has been identified for the first time. Shell model calculations reproduce the level scheme quite well. The level schemes of 137I and 139Cs have been reinvestigated and extended. Their nuclear structure is well described by realistic shell model calculations. The g-factors of the 4+ state in 134Te, 15/2+ state in 135I, and 15/2- state in 137Xe were determined using a newly developed program for angular correlation analysis. The measured g-factors compared favorably with shell model calculations. Octupole correlations are proposed in 141Cs and 142Cs. The variations of D0 in the Cs isotopes exhibit a pronounced drop of dipole moment with increasing neutron number.

136

Effect of deformation and heat treatment on phase transformations and properties of titanium alloys  

International Nuclear Information System (INIS)

Effects of deformation and heat treatment on phase transformations in VT22 and VT22M alloys were studied to reveal the structural factors controlling high strength of titanium alloys and to determine deformation and heat treatment conditions providing satisfactory plastic properties. It is recommended to work the materials in (?+?) phase field at 860 deg C before hardening heat treatment to prevent loss of ductility. It is found that the strength of both alloys is connected with a quantity ratio of ?- and ?-phases and is determined by their structure state

137

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: {yields} Resistance spot welding is successfully used for severely deformed steel sheet. {yields} Microstructures of FZ and HAZ are refined to lower sizes at higher pass number. {yields} Mechanical properties in FZ and HAZ are increased with increasing the pass number. {yields} 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.

Khodabakhshi, F. [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); Kazeminezhad, M., E-mail: mkazemi@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); Kokabi, A.H. [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of)

2011-11-25

138

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

International Nuclear Information System (INIS)

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 HAZostructures of fusion zone and HAZ are refined to lower sizes for larger pre-strained specimens.

139

Creep deformation and rupture property of zircaloy cladding tube  

International Nuclear Information System (INIS)

Creep rupture property of unirradiated zircaloy tube was investigated to obtain basic data for evaluating fuel cladding integrity under dry storage condition. The results obtained were as follows; (1) To predict creep strain up to steady state region, the empirical creep equations were formulated. (2) Rupture time was related to applied stress (?) by Larson-Miller parameter (P), and the ?-P relation were obtained. (3) Method for evaluating fuel cladding integrity was discussed on the basis of the test results. (J.P.N.)

140

Correction of chromatic and geometric aberrations using sextupoles and octupoles  

International Nuclear Information System (INIS)

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 ?P/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 ?P/P = 0% beam striking a 0.1 cm radius target by a factor of 2.5

141

The Recovery of Elastic Properties at 35 °C in TRIP 700 Steel Following Deformation  

Science.gov (United States)

The influence of plastic deformation on the elastic properties that determine the magnitude of springback following forming was investigated using dynamic modulus analysis. For this study, the elastic modulus of TRIP 700 steel was measured continuously at 35 °C and a loading frequency of 1.0 Hz for 1000 min following deformation by cold rolling to varying levels up to 27%. The elastic modulus increased at an exponentially decaying rate during these experiments and with a magnitude that increased with pre-strain. These observations are consistent with the hypothesis that deformation creates microstructural defects that contribute compliance when the stress state changes and that these defects are removed by annealing at this low temperature.

Pitchure, D. J.; Ricker, R. E.

2007-06-01

142

Anisotropy of seismic and mechanical properties of opalinus clay during triaxial and shear deformation  

International Nuclear Information System (INIS)

Knowledge of the complex interacting processes of dilatancy and healing is of vital interest for a characterization of the long term behaviour of a repository, independently from rock type. Constitutive models are needed to describe the development of the EDZ during inelastic closure of excavations in geological formations. They are typically expressed in terms of elastic constants, temperature, stress invariants, humidity, and empirical fitting parameters, assuming, at least, isotropic conditions. However, especially argillaceous rocks are inherently anisotropic. Depending on progressive compaction and a transformation of the originally deposited clay into an over-consolidated clay, clay stone or shale, the rocks become progressively foliated parallel to the bedding due to the sheet structure of the rock forming clay minerals. Although such planar discontinuities can act as preferential flow paths and play an important role on the initiation of inelastic deformation their impact on transport properties and deformation has been largely overlooked. While elastic deformation is usually more or less isotropic, initiation of inelastic deformation and the relative dilatation are clearly a function of bedding plane properties, the spatial orientation and stress geometry. These overlapping effects are particularly important during rock stress redistribution in the EDZ. Amongst others, this laboratory study will focus on the impact of mechanical properties of argillaceous roc mechanical properties of argillaceous rocks on the transport properties with respect to the bedding plane. The points of interest are subdivided in the following tasks: (1) Anisotropy of mechanical and transport properties referred to the bedding plane (2) Onset of dilatancy and its evolution (healing and damage) (3) Mechanical strength of the bedding plane direct shear strength testing. (authors)

143

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

OpenAIRE

Recent prompt ?-ray spectroscopy studies of 149,151Pr have revealed weak octupole correlations. These are manifested by the absence of strong intraband E1 transitions between bands of opposite parities. On the other hand, in their isotones 151,153Pm, which have only two additional protons, the E1 transition rates are several orders of magnitude stronger, indicating enhanced octupole correlations. The quasiparticle phonon model combined with the particle-rotor model, which allows octupole cor...

Thiamova?, Gabriela; Alexa, Petr; Hons, Zdene?k; Simpson, G. S.

2012-01-01

144

The octupole giant resonance strength in 16O  

International Nuclear Information System (INIS)

Angular distributions for polarized proton inelastic scattering cross sections along with the analysing power for the reaction 16O(p(pol),p')16O*(2-,8.88 MeV) at Esub(p)=42.5, 44.0 and 49.3 MeV have been measured. A semidirect reaction analysis augments the evidence for octupole giant resonance strength in the 30 to 50 MeV energy region. (Auth.)

145

A parameter optimization method to determine ski stiffness properties from ski deformation data.  

Science.gov (United States)

The deformation of skis and the contact pressure between skis and snow are crucial factors for carved turns in alpine skiing. The purpose of the current study was to develop and to evaluate an optimization method to determine the bending and torsional stiffness that lead to a given bending and torsional deflection of the ski. Euler-Bernoulli beam theory and classical torsion theory were applied to model the deformation of the ski. Bending and torsional stiffness were approximated as linear combinations of B-splines. To compute the unknown coefficients, a parameter optimization problem was formulated and successfully solved by multiple shooting and least squares data fitting. The proposed optimization method was evaluated based on ski stiffness data and ski deformation data taken from a recently published simulation study. The ski deformation data were used as input data to the optimization method. The optimization method was capable of successfully reproducing the shape of the original bending and torsional stiffness data of the ski with a root mean square error below 1 N m2. In conclusion, the proposed computational method offers the possibility to calculate ski stiffness properties with respect to a given ski deformation. PMID:21451186

Heinrich, Dieter; Mössner, Martin; Kaps, Peter; Nachbauer, Werner

2011-02-01

146

Deformation Properties of Forest Soils in Karelia Affected by "Freeze-Defrost" Cycles  

Directory of Open Access Journals (Sweden)

Full Text Available The impact of “freeze-defrost” cycles on the deformation properties of forest soils has been little studied. The layout of technological schemes of harvesting sites development in off-season periods (spring, fall depends a lot on the formation of ruts when wood harvesting machinery passes. The study of processes occurring in forest soils affected by “freeze-defrost” cycles enables to justify the method of calculating rut depth depending on the number of machinery passes. The compression modulus of deformation, compressibility coefficient and relative compressibility coefficient of clay loam which was collected in the forest of the Republic of Karelia were determined in laboratory conditions. Forest soil samples underwent three “freeze-defrost” cycles. It has been determined clay loam deformation modulus after the first cycle reduces by 16% and after the second and third cycles it reduces by 18% and 25% respectively in relation to the value of deformation modulus before freezing. Compressibility coefficient increases by 18% after the first cycle, it increases by 22% after the second cycle and by 33% after the third one. The decrease of deformation modulus and the increase of clay loam compressibility coefficient are due to changes in the structure of forest soils under the influence of “freeze-defrost” cycles.

Ratjkova E. I.

2013-07-01

147

Effect of viscosity of petroleum products on deformation properties of concrete  

Directory of Open Access Journals (Sweden)

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.

A.P. Svintsov

2014-11-01

148

Microstructure and properties on nano-metals obtained by severe plastic deformation  

International Nuclear Information System (INIS)

The present study provides the review of the structures and properties of nano-metals obtained by service plastic deformation (SPD). The authors also analyze the methods of examining the microstructure and properties of nano-crystalline materials. The size and shape of the grains and the degree of the microstructure homogeneity of the nano-metals produced by SPD were analysed quantitatively. The strength properties were examined by measuring the microhardness and the tensile tests. The temperature stability of the microstructure was determined by examining the recovery and recrystallization kinetics. (author)

149

Tests of octupole band structures using proton scattering and gamma-ray spectroscopy  

International Nuclear Information System (INIS)

In many even-even nuclei, bands of negative parity states have been interpreted as open-quotes octupole bandsclose quotes, which are sequences of vibrational or rotational excitations coupled to a low energy octupole phonon. Careful experimental examination of these structures is of interest because octupole phonons are generally considered to be unstable at high angular momentum. Results from experimental studies of octupole band structures in three nuclei are presented. Two of these nuclei, 144,146Nd, have been studied via inelastic scattering of 35 MeV protons. The third nucleus, 74Se, has been examined using the techniques of high spin gamma-ray spectroscopy

150

Optical and electrical properties of dislocations in plastically deformed GaN  

Science.gov (United States)

Optical and electrical properties of fresh dislocations in GaN bulk crystals deformed plastically at elevated temperatures were reviewed. A dislocation band model was proposed. The fresh dislocations of (a/3) [12bar10]-type edge dislocations on the (101bar0) prismatic plane induced several photoluminescence peaks at around 1.8, 1.9 and 2.4 eV, which implies the formation of radiative recombination centers of the dislocations. Simultaneously, near-band-edge (3.48 eV) photoluminescence intensity decreased remarkably for a high-density of non-radiative recombination centers originating in deformation-induced abundant Ga-vacancy related clusters. The intensity variation of yellow luminescence with plastic deformation and subsequent annealing did not relate to the native property of dislocations. Variation of optical absorption dependent on the strain in plastically deformed GaN was understood in a model of the Franz-Keldysh effect by the electric fields associated with charged dislocations (~5.8 e/nm). Scanning spreading resistance microscopic images showed many spots with high conductivity around the induced dislocations, showing electrical conduction along dislocations according to the Frenkel-Poole mechanism.

Yonenaga, I.; Ohno, Y.; Yao, T.; Edagawa, K.

2014-10-01

151

Effects of plastic deformations on microstructure and mechanical properties of ODS-310 austenitic steel  

International Nuclear Information System (INIS)

Highlights: ? We fabricated a 310 type ODS austenitic steel by the process of MA and HIP. ? Plastic deformations, including forging and hot rolling, were applied to samples. ? Fine Y-Ti-O particles dispersed in a relatively uniform way after forging. ? Ductility increased greatly after deformations, while strength decreased slightly. - Abstract: ODS-310 austenitic steel (Fe–25Cr–20Ni–0.35Y2O3–0.5Ti) was fabricated by the process of mechanical alloying and hot isostatic pressing. Plastic deformations, including forging and hot rolling, were applied to the as-hipped samples to improve the ductility. Microstructural evolutions in samples under different fabrication conditions were characterized by TEM. Tensile properties were tested at 23 °C and 700 °C. Dispersed oxide particles with sizes between 10 nm and 50 nm were characterized to be rich in Y–Ti–O. UTS and elongation of the as-hipped sample were 904 MPa and 11% respectively at 23 °C. Elongation increased two times after plastic deformations while there was only slight decrease in strength properties.

152

Effect of Nb content on deformation behavior and shape memory properties of Ti–Nb alloys  

International Nuclear Information System (INIS)

Highlights: ? Reorientation of martensite variants occurred by the deformation of the {1 1 1} type I and ?2 1 1? type II twins. ? Magnitude of twinning shear in Ti–20Nb is larger than that in Ti–23Nb. ? Ti–20Nb exhibited a higher stress for the reorientation of martensite variants when compared with Ti–23Nb. -- Abstract: Deformation behavior and shape memory properties of Ti–(20, 23) at.% Nb alloys in a single ?? martensite state were investigated. The Ti–20Nb alloy exhibited a higher stress for the reorientation of martensite variants when compared with the Ti–23Nb alloy. The recovery strain due to the shape memory effect in the Ti–20Nb alloy was smaller than that in the Ti–23Nb alloy. Transmission electron microscope (TEM) observation revealed that the reorientation of martensite variants occurred by the deformation of {1 1 1} type I and ?2 1 1? type II twins. The Nb content dependence of the deformation behavior and shape memory properties was discussed considering the magnitude of twinning shear of the twins

153

Anisotropy of seismic and mechanical properties of opalinus clay during triaxial and shear deformation  

Energy Technology Data Exchange (ETDEWEB)

Knowledge of the complex interacting processes of dilatancy and healing is of vital interest for a characterization of the long term behaviour of a repository, independently from rock type. Constitutive models are needed to describe the development of the EDZ during inelastic closure of excavations in geological formations. They are typically expressed in terms of elastic constants, temperature, stress invariants, humidity, and empirical fitting parameters, assuming, at least, isotropic conditions. However, especially argillaceous rocks are inherently anisotropic. Depending on progressive compaction and a transformation of the originally deposited clay into an over-consolidated clay, clay stone or shale, the rocks become progressively foliated parallel to the bedding due to the sheet structure of the rock forming clay minerals. Although such planar discontinuities can act as preferential flow paths and play an important role on the initiation of inelastic deformation their impact on transport properties and deformation has been largely overlooked. While elastic deformation is usually more or less isotropic, initiation of inelastic deformation and the relative dilatation are clearly a function of bedding plane properties, the spatial orientation and stress geometry. These overlapping effects are particularly important during rock stress redistribution in the EDZ. Amongst others, this laboratory study will focus on the impact of mechanical properties of argillaceous rocks on the transport properties with respect to the bedding plane. The points of interest are subdivided in the following tasks: (1) Anisotropy of mechanical and transport properties referred to the bedding plane (2) Onset of dilatancy and its evolution (healing and damage) (3) Mechanical strength of the bedding plane direct shear strength testing. (authors)

Popp, T.; Salzer, K. [Institut fur Gebirgsmechanik GmbH, Leipzig (Germany)

2005-07-01

154

Effects of deformation rates on mechanical properties of PP/SEBS blends  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The goal of this study is to examine effects of tensile deformation rates ( on tensile properties of polypropylene/poly(styrene-b-ethylene-co-butylene-b-styrene copolymer (PP/SEBS blends and to determine suitable for accurate and reliable evaluation of mechanical properties of the blends in accordance with the results of Izod impact tests.Design/methodology/approach: PP/SEBS blends containing ?e = 0, 2.5, 5 and 10 volume % of SEBS thermoplastic elastomer were compounded using a twin-screw extruder, and then moulded with an injection moulding machine. Morphology of PP/SEBS blends were analysed by scanning electron microscopy (SEM. Mechanical properties of the blends were investigated tensile and Izod impact tests. Tensile deformation rates 1= 1.67 ms–1 and 2 = 16.67 ms–1 were used to determine ultimate tensile properties.Findings: Morphological analyses revealed that SEBS elastomer particles were well-dispersed throughout PP matrix in irregular forms with a narrow size distribution and evidenced a two-phase system formation. At low deformation rate ( 1, PP and PP/SEBS blends did not fail during tensile tests despite maximum tensile deformation, ?max = 600%; therefore, tensile toughness (UT, stress and strain values at break point (?b and ?b of the blends were not determined. However, at high deformation rate ( 2, all specimens tested in this study failed; a slight decrease in ?b of the blends with SEBS elastomer was associated with a significant increase in ?b and UT. Strain-rate-sensitivity of PP/SEBS blends was promoted with SEBS elastomer.Research limitations/implications: Mechanical properties determined through high-velocity tests are beyond the scope of this study.Practical implications: of tensile testing machines is readily adjustable, while ?max of tensile testing machines is limited. Consequently, in order to evaluate reliably mechanical properties of ductile materials like PP/SEBS blends, must be so high that ductile materials can fail during tensile tests.Originality/value: Tensile testing at high strain rate 2 was concluded to be more suitable for evaluation of mechanical properties of PP/SEBS blends than that of at low strain rate.

O. Balkan

2011-07-01

155

Exotic Collective Excitations at High Spin: Triaxial Rotation and Octupole Condensation  

CERN Document Server

In this thesis work, two topics, triaxiality and reflection asymmetry, have been discussed. Band structures in $^{163}$Tm were studied in a "thin" target experiment as well as in a DSAM lifetime measurement. Two new excited bands were shown to be characterized by a deformation larger than that of the yrast sequence. These structures have been interpreted as Triaxial Strongly Deformed bands associated with particle-hole excitations, rather than with wobbling. Moreover, the Tilted-Axis Cranking calculations provide a natural explanation for the presence of wobbling bands in the Lu isotopes and their absence in the neighboring Tm, Hf and Ta nuclei. A series of so-called "unsafe" Coulomb excitation experiments as well as one-neutron transfer measurements was carried out to investigate the role of octupole correlations in the $^{238,240,242}$Pu isotopes. Some striking differences exist between the level scheme and deexcitation patterns seen in $^{240}$Pu, and to a lesser extent in $^{238}$Pu, and those observed in...

Wang, Xiaofeng

2008-01-01

156

Variation of hydraulic properties on sedimentary rock due to shear deformation  

International Nuclear Information System (INIS)

In order to investigate the variation of hydraulic properties on soft rock due to shear deformation, permeability tests were performed on hard shale of the Wakkanai formation by axial flow and radial flow techniques under triaxial compression. The experimental results showed that the axial direction permeability increased to approximately 10 times larger than the initial one in residual strength zone. On the other hand, the radial direction permeability increased remarkably in strain softening zone. (author)

157

Deformation properties of the scissors mode in the generalized coherent state model  

International Nuclear Information System (INIS)

The deformation properties of the low-lying magnetic dipole excitations, known as scissors mode, are systematically studied within the framework of the generalized coherent state model. The present description is shown to be closely related to other interacting boson approaches as well as to the geometrical two-rotor model. The results are in good agreement with experiments and consistent with those obtained in other phenomenological as well as microscopic approaches

158

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

Science.gov (United States)

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.

Reed, R. P.

1972-01-01

159

Mechanical properties of reinforced concrete exposed to salt injury condition. Flexural capacities and deformation properties of reinforced concrete beams  

International Nuclear Information System (INIS)

It is described that the estimation method of mechanical performance of reinforced concrete deteriorated by salt injury will be established. In the study, the influence of reinforcement corrosion on flexural capacities and deformational properties were investigated through the results of indoor tests and exposure tests at the sea sides. Followings are the main conclusions obtained from the study. 1. The relationship between reinforcement corrosion and flexural capacities, deformational properties obtained by the indoor tests are almost the same as those by the exposure tests. 2. Corrosion of tensile reinforcement causes deterioration of bond performance between steel and concrete and changes crack patterns. 3. Deformational properties of reinforced concrete with the corrosion volume of under 100 mg/cm2 are hardly different from those without corrosion. 4. Flexural capacities of reinforced concrete decreased with the increase of reinforcement corrosion. Using the JSCE (Japanese Society of Civil Engineers) method and taking account of loss of cross section of reinforcement due to corrosion, yield and ultimate strengths can be calculated. (author)

160

Fatigue properties of magnesium alloy AZ91 processed by severe plastic deformation.  

Science.gov (United States)

Fatigue properties of cast AZ91 magnesium alloy processed by severe plastic deformation were investigated and compared with the properties of the initial cast state. The severe plastic deformation was carried out by equal channel angular pressing (ECAP). The ECAP treatment resulted in a bimodal structure. The bimodality consists in a coexistence of fine grained areas with higher content of Mg17Al12 particles and areas exhibiting larger grains and lower density of Mg17Al12 particles. Improvement of the basic mechanical properties of AZ91 (yield stress, tensile strength and ductility) by ECAP was significant. Also the improvement of the fatigue life in the low-cycle fatigue region was substantial. However the improvement of the fatigue strength in the high-cycle fatigue region was found to be negligible. The endurance limit based on 10(7) cycles for the cast alloy was 80MPa and for the alloy processed by ECAP 85MPa. The cyclic plastic response in both states was qualitatively similar; initial softening was followed by a long cyclic hardening. Fatigue cracks in cast alloy initiate in cyclic slip bands which were formed in areas of solid solution. In the case of severe plastic deformed material with bimodal structure two substantially different mechanisms of crack initiation were observed. Crack initiation in slip bands was a preferred process in the areas with large grains whereas the grain boundaries cracking was a characteristic mechanism in the fine grained regions. PMID:25498295

Fintová, Stanislava; Kunz, Ludvík

2015-02-01

161

The effect of aluminum alloying on strength properties and deformation mechanisms of the Hadfield steel single crystals  

Science.gov (United States)

The role of aluminum alloying on strength properties and deformation mechanisms (slip, twinning) of single crystals of Hadfield steel under tensile loading at T = 300 K is demonstrated. It is found out that aluminum alloying suppresses twinning deformation in the single crystals and, during slip, results in a dislocation structure change from a uniform dislocation distribution to a planar dislocation structure.

Astafurova, E. G.; Tukeev, M. S.; Chumlyakov, Yu. I.

2007-10-01

162

Using Octupoles for Background Control in Linear Colliders an Exploratory Conceptual Study  

CERN Document Server

If one adds a suited Octupole (or an even higher multipole) lattice to linear collider Quadrupole FODO lattices, the amplifying properties of the combined lattice drive particles in the tails, but not those in the core, into resonant losses. This approach is quite different in concept and beam dynamics impact from past proposed use of non-linear elements for collimation. This non-traditional scheme for background control has the added advantage that most, or maybe all, of the Halo collimation can be done using the lever arm of the real estate of the main accelerators, thus reducing the costly length of a separate dedicated collimation section and also unifying machine protection and background control. Simulations of particle distributions are presented. This approach requires co operation by the designers of the accelerators, the beam delivery system, and the Detector, because a careful balance between sometimes conflicting requirements has to be found. As a second component of this approach the use of Octup...

Pitthan, R

1999-01-01

163

Analysis on the Soil Dynamic Properties and Accumulated Deformation under the Rail Traffic Loads  

Directory of Open Access Journals (Sweden)

Full Text Available The dynamic behaviors of soil under the rail traffic load are obviously different from that under the other loads such as earthquake load and wave load. So the dynamic properties of soil under the rail traffic must be studied in specially. In this paper, the existing studies are summarized and analyzed in several aspects such as the dynamic properties of soil by testing, the constitutive model with considering the cyclic principal stress rotation, the calculated method for accumulated deformation of soil and the model test. Some shortages in existing studies are analyzed and some scientific questions which are worthy to be researched further are mentioned.

Liwei Shen

2014-03-01

164

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

International Nuclear Information System (INIS)

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)

165

Conflicting results for the deformation properties of forsterite, Mg2SiO4  

International Nuclear Information System (INIS)

Deformation properties of forsterite have been deduced simultaneously from X-ray diffraction data affected by extinction in Bonn-Pittsburgh (B), and in Groningen (G). For the G crystals, GI and GII, extinction is anisotropic and considerably larger than for crystal B. Measurements were made with Mo radiation for B, and with Mo and Ag radiation for GI and GII. As the Becker and Coppens extinction model is not exact, the deformation properties had to be filtered from the data with refinement models. The flexible B model [?'s and populations for single exponential functions (SEF's) refined for l=0-4] and the more rigid G model (SEF's populations refined for l=0-3 and ? for l=0; further ?'s and n's fixed at standard values) yield different results. Refinement of ? makes the majority of the SEF's notably diffuse, presumably due to correlation with incorrect extinction corrections. The order of the deformation potentials at the Mg(1) and Mg(2) sites is reversed for B and G. Maxima on the Si-O bonds, which are polarized towards O, are smaller for G (0.20-0.25 e A-3) than for B (0.25-0.45 e A-3). Although each of the two sets of deformation properties looks acceptable by itself, the present comparison shows that neither of them may be sufficiently close to the truth. The diffraction data are available on request from the Electron Density Data Bank (Professor H. Burzlaff, Institut fuer Angewandte Physik, Bismarckstrasse 10, D-8520 Erlangen, Federal Retrasse 10, D-8520 Erlangen, Federal Republic of Germany). Details of the measurements are described in the paper. (orig.)

166

Erythrocyte membrane deformability and stability: two distinct membrane properties that are independently regulated by skeletal protein associations  

OpenAIRE

Skeletal proteins play an important role in determining erythrocyte membrane biophysical properties. To study whether membrane deformability and stability are regulated by the same or different skeletal protein interactions, we measured these two properties, by means of ektacytometry, in biochemically perturbed normal membranes and in membranes from individuals with known erythrocyte abnormalities. Treatment with 2,3-diphosphoglycerate resulted in membranes with decreased deformability and de...

1986-01-01

167

Designing electronic properties of two-dimensional crystals through optimization of deformations  

Science.gov (United States)

One of the enticing features common to most of the two-dimensional (2D) electronic systems that, in the wake of (and in parallel with) graphene, are currently at the forefront of materials science research is the ability to easily introduce a combination of planar deformations and bending in the system. Since the electronic properties are ultimately determined by the details of atomic orbital overlap, such mechanical manipulations translate into modified (or, at least, perturbed) electronic properties. Here, we present a general-purpose optimization framework for tailoring physical properties of 2D electronic systems by manipulating the state of local strain, allowing a one-step route from their design to experimental implementation. A definite example, chosen for its relevance in light of current experiments in graphene nanostructures, is the optimization of the experimental parameters that generate a prescribed spatial profile of pseudomagnetic fields (PMFs) in graphene. But the method is general enough to accommodate a multitude of possible experimental parameters and conditions whereby deformations can be imparted to the graphene lattice, and complies, by design, with graphene's elastic equilibrium and elastic compatibility constraints. As a result, it efficiently answers the inverse problem of determining the optimal values of a set of external or control parameters (such as substrate topography, sample shape, load distribution, etc) that result in a graphene deformation whose associated PMF profile best matches a prescribed target. The ability to address this inverse problem in an expedited way is one key step for practical implementations of the concept of 2D systems with electronic properties strain-engineered to order. The general-purpose nature of this calculation strategy means that it can be easily applied to the optimization of other relevant physical quantities which directly depend on the local strain field, not just in graphene but in other 2D electronic membranes.

Jones, Gareth W.; Pereira, Vitor M.

2014-09-01

168

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

Directory of Open Access Journals (Sweden)

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.

Daniel Fruchart

2012-08-01

169

Theory of the effect of deformation on the relaxation and mechanical properties of polymer glasses  

Science.gov (United States)

Recently Saltzman and Schweizer have developed a statistical dynamical theory of segmental relaxation in deeply supercooled polymer melts by combining and extending methods of mode coupling, dynamic density functional and activated barrier hopping theories. The approach is built on the concept of a nanometer scale nonequilibrium free energy which quantifies dynamic localization due to interchain forces. We have now generalized this approach to treat quiescent relaxation, physical aging, and nonlinear mechanical properties in the nonequilibrium glass state. Applied stress weakens dynamical constraints in the effective free energy which accelerates alpha relaxation and softens the elastic modulus. A constitutive equation has been constructed which allows the prediction of dynamic yielding and mechanical response under constant strain rate, constant stress (creep), and other modes of deformation. Multiple predictions that fundamentally differ from the phenomenological Eyring model are made for the temperature and strain rate dependence of the dynamic yield stress and the deformation modified segmental relaxation time. Comparison of the theoretical results with experiments on PMMA reveals good agreement. The coupling of stress and aging, the strain softening effect, and large deformation strain hardening, can also be treated within our approach.

Chen, Kang; Schweizer, Kenneth

2008-03-01

170

Effect of deformation rate on characteristics of mechanical properties of heat treated titanium alloys  

International Nuclear Information System (INIS)

Effect of the deformation rate on strength and plasticity of industrial VT3-1 and VT23 alloys after hardening heat treatment has been investigated. Change in the deformation rate in mechanical tests from the minimum (3.3x10-1 s-1) to the maximum (1.67x10-4 s-1) admissible by the All-Union State Standard is shown to cause the increase of timing resistance of VT3-1 and VT23 alloys by 40...50 MPa, and relative elongation of the VT3-1 alloy decreases by 3%, VT23 alloy does not change practicallyy, relative contraction increases by 8% (VT3-1) and 15% (VT23). The VT23 alloy by virtue of composition and structure peculiarities with strength being practically equal to the VT3-1 alloy has higher values of ductile characteristics. Increase of the deformation rate of the VT3 alloy leads to substantial localization of plastic flow in the sample neck with conservation of high relative elongation. Increase of the strain rate in the range of 3.3x10-5...3.3x10-1 s-1 leads to increase in dipression of mechanical properties of VT3-1 and VT23 alloys in the heat treated state

171

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

DEFF Research Database (Denmark)

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 material. In contrary, cold rolling to large strain (50%) results in significant strengthening. This leads to the suggestion of a transition strain within the range of 25-35% reduction by rolling. The microstructural evolution during post-process deformation has been followed by transmission electron microscopy showing a significant change in the dislocation structure when the strain is increased. Based on the experimental observations the mechanical behavior is related to the structural changes focusing on the characteristics of the dislocation structure present between the narrowly spaced lamellar boundaries in the deformed structure.

Huang, Xiaoxu; Kamikawa, Naoya

2008-01-01

172

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

International Nuclear Information System (INIS)

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.

173

Non-yrast spectra of odd-A nuclei in a model of coherent quadrupole-octupole motion  

CERN Document Server

The model of coherent quadrupole and octupole motion (CQOM) is applied to describe non-yrast split parity-doublet spectra 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-doublet structures are obtained as higher-energy rotation-vibration modes coupled to excited s.p. states. It is shown that the extended model scheme describes both the yrast and non-yrast quasi parity-doublet spectra and the related B(E1) and B(E2) transition rates in different regions of heavy odd-A nuclei. The involvement of the reflection-asymmetric deformed shell model to describe the single-particle motion and the Coriolis interaction on a deeper level is discussed.

Minkov, N; Drumev, K; Strecker, M; Lenske, H; Scheid, W

2013-01-01

174

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

International Nuclear Information System (INIS)

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

175

Influence of plastic deformation and diffusion annealing on the properties of on copper plated VT9 titanium alloy  

International Nuclear Information System (INIS)

The phase composition, microhardness, wear- and erosion resistance of the surface layers of the VT9 titanium alloy which is plated with copper when combining plastic deformation and diffusional annealing are investigated. It is established that plastic deformation of the copper plated samples of the VT9 alloy combined with diffusional annealing results in the acceleration of mutual diffusion processes which is manifested in the formation of a wider diffusion zone with the improved physico-mechanical properties. The highest strengthening H 600-650 is observed on the samples plastically deformed both before plating and after it

176

Deformed photon-added nonlinear coherent states and their non-classical properties  

Science.gov (United States)

In this paper, we will try to present a general formalism for the construction of deformed photon-added nonlinear coherent states (DPANCSs) |?, f, mrang, which in a special case lead to the well-known photon-added coherent state (PACS) |?, mrang. Some algebraic structures of the introduced DPANCSs are studied and particularly the resolution of the identity, as the most important property of generalized coherent states, is investigated. Meanwhile, it will be demonstrated that the introduced states can also be classified in the f-deformed coherent states, with a special nonlinearity function. Next, we will show that these states can be produced through a simple theoretical scheme. A discussion on the DPANCSs with negative values of m, i.e. |?, f, -mrang, is then presented. Our approach has the potentiality to be used for the construction of a variety of new classes of DPANCSs, corresponding to any nonlinear oscillator with known nonlinearity function, as well as arbitrary solvable quantum system with known discrete, non-degenerate spectrum. Finally, after applying the formalism to a particular physical system known as the Pöschl-Teller (P-T) potential and the nonlinear coherent states corresponding to a specific nonlinearity function f(n)=\\sqrt{n}, some of the non-classical properties, such as the Mandel parameter, second-order correlation function, in addition to first- and second-order squeezing of the corresponding states, will be investigated numerically.

Safaeian, O.; Tavassoly, M. K.

2011-06-01

177

The influence of strain rate, deformation temperature and stacking fault energy on the mechanical properties of Cu alloys  

Energy Technology Data Exchange (ETDEWEB)

Cu–Ge alloys with different stacking fault energies (SFEs) were prepared by induction melting and processed by severe plastic deformation (SPD) using three different deformation techniques, including rolling at room temperature (RTR), rolling at the liquid nitrogen temperature (LNR), and Split Hopkinson Pressure Bar (SHPB) impact followed by room temperature rolling (HK+RTR). The effects of SFE, strain rate and deformation temperature on the microstructures and mechanical properties were systematically investigated by X-ray diffraction analyses and tensile tests. It was found that the dislocation density and twin density of all the Cu alloys after the SPD processing increased with decreasing SFE, increasing strain rate or reducing deformation temperature, which led to simultaneously enhanced strength and improved ductility due to effective grain refinement. The mechanical properties of the Cu alloys can be optimized to a combination of high strength and excellent ductility by lowering the SFE, the intrinsic property of metals, or manipulating the extrinsic deformation conditions, that is, increasing strain rate, and/or decreasing deformation temperature.

Gong, Y.L. [Faculty of Science, Kunming University of Science and Technology, Kunming, Yunnan (China); Wen, C.E. [Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, John Street, Hawthorn, Victoria 3122 (Australia); Wu, X.X.; Ren, S.Y.; Cheng, L.P. [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan (China); Zhu, X.K., E-mail: xk_zhu@hotmail.com [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan (China)

2013-10-20

178

Plasma resistivity measurements in the Wisconsin levitated octupole  

International Nuclear Information System (INIS)

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/

179

Plasma resistivity measurements in the Wisconsin levitated octupole  

Energy Technology Data Exchange (ETDEWEB)

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/.

Brouchous, D. A.

1980-11-01

180

Two-phonon-octupole excitation in 208Pb  

International Nuclear Information System (INIS)

In the framework of the present thesis quasi-elastic processes in the reactions 206 Pb+208 Pb and 208 Pb+208 Pb were studied at an incident energy slightly above the Coulomb barrier (6.2 MeV/u) were studed. By means of the measured Particle-gamma correlations the quasi-elastic collisions were separated from the deep inelastic ones. Determined were the absolute cross sections and angular distributions of the exitation by inelastic collisions as well as by one- and two-neutron transfer. For the states excited by inelatic scattering the multiplicities of the ? quanta emitted in their decay were experimentally determined. The measured angular distributions of the inelastic reactions were compared with CCBA calculations. As most important result of this thesis the experimental detection of a member of the 2-phonon-octupole multiplet is to be considered. A hitherto unknown ? transition in the spectrum of -2-0-8 Pb with an energy of 2.485 MeV was detected. Because of the measured ?? coincidence ratios in 208 Pb this transition was assigned to the level scheme of 208Pb. Its decay to the 1-phonon state 3- pursues via an E1-transition to the 5- -state and a following E2-transition. The angular distribution of the 2-phonon-octupole state was calculated in the framework of the CCBA and compared with the experiment. The comparison with the CCBA calculation indicates a spin of I?=6+ or 4+ . The experimental angular distributions of the one-neutron transfer reactions to 207 Pb and 209 Pb were compared with DWBA calculations. (orig./HSI)

181

Deformation and drag properties of drops subjected to shock-wave and steady disturbances  

Science.gov (United States)

The deformation and drag properties of round drops subjected to shock-wave and steady disturbances were studied computationally. The objective was to consider secondary breakup of drops at small liquid/gas density ratios and large Ohnesorge numbers that are difficult to address by experiments but are more representative of conditions in practical high-pressure combusting sprays. The calculations were evaluated based on measurements of wake lengths and drag properties for solid spheres, the deformation of drops under a constant body force and measurements of secondary breakup properties of drops at large liquid/gas density ratios. The agreement between predictions and measurements was quite good. It was found that effects of liquid/gas density ratio on the secondary breakup of drops was remarkably small. The results showed that for small Ohnesorge numbers (Oh 1), however, the liquid/gas viscosity ratio has a dominating effect. Plotting the ratio of drag to liquid viscous forces, We^1/2/Oh, as a function of the ratio of surface tension to liquid viscous forces, 1/Oh, yielded breakup regime boundaries that are relatively independent of both the liquid/gas density ratio and the Ohnesorge number if surface tension is small. Another effect that was observed was a progressive increase of the breakup regime boundaries in terms of We and We^1/2/Oh as the Reynolds number of the initial flow was decreased below values of 10, probably caused by the progressive increase of the drag coefficient as the Stokes flow regime is approached.

Aalburg, Christian; van Leer, Bram; Faeth, Gerard M.

2001-11-01

182

Improvement of mechanical properties in severely plastically deformed Ni–Cr alloy  

International Nuclear Information System (INIS)

Highlights: ? The application of cross-roll rolling to the Ni–20Cr alloy effectively enhanced grain refinement. ? This grain refinement in cross-roll rolling directly improved the mechanical properties. ? Particularly, yield strength increased to 800% relative to those of the initial material. ? We discussed the increase in mechanical properties in terms of the grain refinement and texture development. -- Abstract: This study was carried out to evaluate the grain refining and mechanical properties in alloys that undergo severe plastic deformation (SPD). Conventional rolling (CR) and cross-roll rolling (CRR) were introduced as methods for SPD, and a Ni–20Cr alloy was selected as the experimental material. The materials were cold rolled to 90% thickness reduction and subsequently annealed at 700 °C for 30 min to obtain the fully recrystallized microstructure. The annealed materials after cold rolling were assessed through electron backscattered diffraction (EBSD) analysis to investigate the grain boundary characteristic distributions (GBCDs). The CRR process was more effective than the CR process in developing grain refinement; the grain size decreased from 70 ?m in the initial material to 4.2 ?m (CR) and 2.4 ?m (CRR), respectively. The grain refinement affected mechanical properties such as microhardness, yield, and tensile strength, which were significantly increased relative to the initial material.

183

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

Science.gov (United States)

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. The first authors Y De Deene and P S Skyt made an equivalent contribution to the experimental work presented in this paper.

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

2015-02-01

184

Strength and deformational properties of concrete at elevated temperatures up to 5000C  

International Nuclear Information System (INIS)

Mechanical property tests of concrete at elevated temperatures had been performed. The experimental results obtained by the strength tests, were shown at each strength test. Compressive strength: sigmacu(T)/sigmacu, room = 1.00(normal temp. 0C), sigmacu(T)/sigmacu, room = -0.00195T + 1.544(280 0C -6T2 + 4.813 x 10-5T + 1.0(normal temp. 0C); Modulus of Rupture: sigmabu(T)/sigmabu, room = -0.0021T + 1.402(100 0C 0C); Young's Modulus: Esub(c)(T)/Esub(c), room = -0.00124T + 0.802(100 0C 0C); Relationship between Decrease rates of Young's Modulus(W) and Weight of Test Specimen(G): W = 0.047G + 2.88(100 0C 0C); compressive Strain at the Maximum Stress: R strain = 0.00263T + 0.932(normal temp. 0C), which means the ratio of the compressive strain at maximum stress at high temperature to that at normal temperature. It was made clear by the past researches that the thermal expansion coefficients of deformed bars increase according to temperature rise. The experimental results obtained by the free expansion tests using D16 deformed bars in Civil Engineering Laboratory supported the general tendency described above. Further, the strengths as well as Young's modulus of concrete at es well as Young's modulus of concrete at elevated temperatures were discussed. (Kubozono, M.)

185

Deformation mechanisms, length scales and optimizing the mechanical properties of nanotwinned metals  

International Nuclear Information System (INIS)

Refinement of microstructural length scales and modification of interface character offer opportunities for optimizing material properties. While strength and ductility are commonly inversely related, nanotwinned polycrystalline copper has been shown to possess simultaneous ultrahigh strength and ductility. Interestingly, a maximum strength is found at a small, finite twin spacing. We study the plastic deformation of nanotwinned polycrystalline copper through large-scale molecular dynamics simulations. The simulations show that plastic deformation is initiated by partial dislocation nucleation at grain boundary triple junctions. Both pure screw and 60o dislocations cutting across twin boundaries and dislocation-induced twin boundary migration are observed in the simulation. Following twin boundary cutting, 60o dislocations frequently cross-slip onto {0 0 1} planes in twin grains and form Lomer dislocations. We further examine the effect of twin spacing on this Lomer dislocation mechanism through a series of specifically designed nanotwinned copper samples over a wide range of twin spacings. The simulations show that a transition in the deformation mechanism occurs at a small, critical twin spacing. While at large twin spacings, cross-slip and dissociation of the Lomer dislocations create dislocation locks that restrict and block dislocation motion and thus enhance strength, at twin spacings below the critical size, cross-slip does not occur, stepical size, cross-slip does not occur, steps on the twin boundaries form and deformation is much more planar. These twin steps can migrate and serve as dislocation nucleation sites, thus softening the material. Based on these mechanistic observations, a simple, analytical model for the critical twin spacing is proposed and the predicted critical twin spacing is shown to be in excellent agreement both with respect to the atomistic simulations and experimental observations. In addition, atomistic reaction pathway calculations show that the activation volume of this dislocation crossing twin boundary process is consistent with experimental values. This suggests that the dislocation mechanism transition reported here for the first time can be a source of the observed transition in nanotwinned copper strength.

186

Microstructure and Properties of Deformation Processed Polycrystalline Ni47Ti44Nb9 Shape Memory Alloy  

Science.gov (United States)

The objective of this work was to investigate the relationships between process and microstructure and property in polycrystalline Ni47Ti44Nb9 alloy. Three processes: (1) hot-forged, (2) cold-drawn, and (3) cold-rolled were investigated. The microstructure was tested by means of optical microscope, x-ray diffraction, and electron backscatter diffraction, and then crystalline orientation distribution functions and inverse pole figures were measured. The results indicated that hot-forging eliminated dendritic microstructure and fined the eutectic structure. It also induced a fiber texture, which paralleled to the axial direction. The cold drawing and cold-rolling had a further effect in grain refinement. And the cold-drawn specimens contained a strong fiber texture paralleling to the deformation direction, while the cold-rolled tubes formed crystalline directions paralleling the axial direction and crystalline directions of crystalline arranged along the circumferential direction. The notably distinctive recoverability of different processed materials was observed and discussed.

Yin, XiangQian; Mi, Xujun; Li, Yanfeng; Gao, Baodong

2012-12-01

187

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

International Nuclear Information System (INIS)

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 ?2 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.)

188

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

International Nuclear Information System (INIS)

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 ?3 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 ?3. The literature has been covered to March 1988

189

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

International Nuclear Information System (INIS)

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

190

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2013-09-06

191

Deformation Mapping and the Role of Carbides on the Microstructure and Properties of Evolved Adiabatic Shear Bands  

Science.gov (United States)

Impacting hardenable steel such as 4340, results in the formation of adiabatic shear bands (ASBs). Previous studies have shown that the presence of carbides/second-phase particles in the pre-deformation microstructures of 4340 steel increases their susceptibility to the formation of ASBs. The current study examines the role of carbides on the microstructure and properties within evolved ASBs in 4340 steel after impact. Geometric phase analysis was used to map local deformation fields within the evolved ASBs. It was observed that carbide fragmentation due to plastic deformation of carbides produces both residual carbides and residual carbide particles in regions away from the shear bands. Extensive carbide fragmentation produces fine residual carbide particles which are redistributed within the ASBs. This is attributed to strain localization within the ASBs which result in higher local strain and strain rates within the shear bands than in regions outside the bands. In addition, it is observed that the residual carbide particles trap and pin dislocations within the shear bands and contribute to an increase in local hardening. A more homogenous distribution of narrower and shorter rotational and shear-strain fields were revealed by the local deformation maps within the evolved ASBs. Lattice deformation mapping revealed that the ferrite matrix, prior to impact, had broader and longer rotational and shear-strain fields perpendicular to the direction of impact. This is attributed to lattice-invariant deformation and shape deformation processes that occur on specific crystallographic planes during martensitic transformation. It is concluded that strain localization during high strain rate deformations does not occur on specific crystallographic planes. This results in a more regular distribution of internal lattice rotational and strain fields within the evolved ASBs.

Boakye-Yiadom, Solomon; Khan, Abdul Khaliq; Bassim, Nabil

2014-11-01

192

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

International Nuclear Information System (INIS)

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

193

Evidence for octupole vibration in the triaxial superdeformed well of 164Lu  

International Nuclear Information System (INIS)

High-spin states in 164Lu were populated in the 121Sb(48Ca,5n) reaction at 215 MeV and ?-ray coincidences were measured with the Gammasphere spectrometer. Through this experiment the eight known triaxial superdeformed bands in 164Lu could be confirmed. Some of these bands were extended to higher as well as to lower spins. Evidence is reported for the first time for weak ?I=1,E1 transitions linking TSD3 and TSD1. This observation may imply coupling to octupole vibrational degrees of freedom. The decay mechanism is different from the one observed in the neighboring even-N isotopes, which exhibit wobbling excitations built on the ?i13/2 structure with E2(M1),?I=1 interband decay. An additional sequence decaying at high spin into TSD1 was observed up to I?=(50-). This band has a constant dynamic moment of inertia of ?70(?/2?)2MeV-1 and an alignment that is ?2(?/2?) larger than that found for TSD1. A revision of the assumed spin-parity-assignment of TSD2 is based on the observed decay-out to normal-deformed structures. The parity and signature quantum numbers of TSD2 are now firmly assigned as (?,?)=(+,0), in disagreement with the former assignment of (?,?)=(-,1), which was based on the assumption that TSD2 is the signature partner of TSD1. TSD1 and TSD2 show an alignment gain at (?/2?)??0.67 and 0.60 MeV, respectively. In TSD1 the involvement of the volvement of the j15/2 neutron orbital is suggested to be responsible for the high-frequency crossing

194

On the chemistry, microstructure, and deformation properties of cement pastes: Towards a new strategy for controlling drying shrinkage  

Science.gov (United States)

The research reported in this thesis covers a number of topics that include aspects of chemistry, microstructure, deformation of cement pastes. An overall goal has been to develop a materials science basis for controlling drying shrinkage. This goal is ambitious and there is a great deal of research still required. However, progress has been made and it is reported here. First, a new phase diagram believed to be consistent with the cement hydration process has been developed. This diagram assumes that a metastable C-S-H phase, analogous to jennite but without polymerized silicate chains, is responsible for the induction period, and that the final hydration reaction is a eutectic solidification reaction consisting of layered calcium silicate hydrate and calcium hydroxide. Second, the effects of chemical admixtures on the rheological behavior of cement in its fluid state was explored. It was found that steric hindrance must play a role in the mechanism behind the dispersing properties of these chemicals. Third, new deformation mapping technique used to investigate the drying shrinkage behavior of neat cement pastes has been developed. This technique requires only two digital images; the source of the images and the source of the deformation does not affect this analysis. A dynamic new picture of drying shrinkage deformation has emerged. Both rarefactions and compactions are found to develop within the microstructure under all drying conditions, and these deformed regions interact to control the overall deformation of the material. Finally, a finite element model was used to further explore drying shrinkage in cement pastes and mortars. It was found that the drying shrinkage of neat cement pastes appears to be controlled by only a subset of calcium silicate hydrate; this subset is detectable by nitrogen sorption techniques. This relationship is perhaps the second microstructure-property relationships known for cement pastes and can be used as a design tool for developing new materials with optimum drying shrinkage properties.

Neubauer, Christopher Michael

195

Frequency standard based on the octupole transition in 171Yb+  

International Nuclear Information System (INIS)

W present our results on the development of a new optical frequency standard based on the electric octupole (E3) transition 2S1/2(F=0) ? 2F7/2(F=3) of a single trapped laser-cooled 171Yb+ ion at 467 nm. In comparison with a previously realized optical frequency standard in 171Yb+ this E3 transition benefits from smaller systematic level shifts due to external fields and its negligible natural linewidth. Another important aspect of the new standard is its strong dependence on variations of the fine structure constant ?. A recently built probe laser system and the use of a new efficient repump scheme allows to observe Fourier transform-limited linewidths below 7 Hz and a resonant excitation probability of more than 90 %. We lock the probe laser frequency to the resonance signal of the E3 transition and use a real-time extrapolation scheme to eliminate the huge light shift induced by the probe field. The unperturbed transition frequency was measured by a comparison to a caesium fountain clock using a frequency comb generator. The resulting uncertainty was mainly limited by the systematic uncertainty of the fountain clock.

196

Detailed investigation of octupole vibrational states in {sup 168}Yb  

Energy Technology Data Exchange (ETDEWEB)

The experimental evidence for the presence of octupole vibrational states in {sup 168}Yb is presented. In order to populate the excited states in this nucleus, the {sup 166}Er(?,2n?){sup 168}Yb fusion evaporation reaction was used with a beam energy of 24 MeV. Using the coincidence method, the level scheme was corrected and extended up to 3 MeV, both for the positive and negative parity states. In a second step, the lifetimes of five excited states were measured by using the fast timing method with the Bucharest HPGe and LaBr{sub 3}:Ce detector array using the triple-? coincidence method. Reduced E1 and E2 transition probabilities were extracted from the measured lifetimes and compared, when possible, with similar observables in neighboring isotopes, showing a smooth behavior with increasing mass. The positive and negative-parity states revealed by this experiment are compared with the Interacting Boson Model and are found to be in good agreement.

Pascu, Sorin; Derya, Vera; Endres, Janis; Hennig, Andreas; Netterdon, Lars; Pickstone, Simon G.; Spieker, Mark; Zilges, Andreas [Institut fuer Kernphysik, Universitaet Koeln (Germany)

2013-07-01

197

Fifth-order aberrations in magnetic quadrupole-octupole systems  

International Nuclear Information System (INIS)

Explicit integral expressions are given for the fifth-order geometrical aberration coefficients in rectilinear magnetic quadrupole-octupole systems used for the transport of nonrelativistic charged particle beams. The numerical values of the fifth-order geometrical aberration coefficients for a rare earth cobalt (REC) quadrupole doublet are given as an example. In the calculations presented here, the author has used Mathematica on a NeXT computer to generate the results. Mathematica provides options to write expressions in a form suitable for input to TEX, or in formats that can be inserted into C or FORTRAN programs. The expressions in Appendix A and C are generated and put into TEX form by Mathematica. The organization of the paper is as follows. The basic equations used here are given in Sec. II while the paraxial and third-order solutions are given in Sec. III and IV respectively. Explicit integral expressions for the fifth-order geometrical aberration coefficients are given in Sec. V. In Sec. VI, numerical values for the third- and fifth-order geometrical aberration coefficients of a REC quad doublet are given. Finally, some concluding remarks are given in Sec. VII

198

The effect of mechanical deformation on magnetic properties and MRI artifacts of type 304 and type 316L stainless steel.  

Science.gov (United States)

The purpose of this study was to evaluate the influence of composition and deformation of biomedical stainless steels on mechanical properties, magnetic properties, and MRI artifacts. Type 304 and Type 316L samples were prepared using standard wire-drawing techniques. Mechanical properties were determined using standard test methods. The amount of ferromagnetic phase present was estimated using a Severn Gage and x-ray diffraction. Magnetic field attraction and artifacts were determined using previously described techniques. The strength of both steels increased significantly with increasing deformation. None of the type 316L wires transformed to the magnetic phase. The amount of magnetic phase in the type 304 wires increased with increasing deformation. There was no magnetic field attraction, and artifacts were minimal for all of type 316L wires and the undeformed type 304 wire. Deflection and artifacts were significant for the deformed type 304 stainless steel. These results provide guidance regarding the use of type 304 and type 316L stainless steels for bioimplants. In this regard, type 316L stainless steel seems to be a more acceptable material with respect to MR compatibility. PMID:9400866

Bendel, L P; Shellock, F G; Steckel, M

1997-01-01

199

Effect of plastic deformation on the transport properties of Bi(2212)-Ag composites  

International Nuclear Information System (INIS)

The effect has been studied of elastic and plastic (to 50%) deformation on the current-carrying capacity of a composite representing a silver wire covered with a HTSC film of a bismuth ceramic (2212 phase). It has been found that this composite provided flowing of superconducting current under deformations of up to 30%. A model is proposed which describes degradation of the transport current of the composites and provides satisfactory quantitative explanation to the said effect in a wide range of deformations

200

Effect of superplastic deformation on the bonding property of 00Cr25Ni7Mo3N duplex stainless steel  

Science.gov (United States)

The superplastic deformation diffusion bonding of 00Cr25Ni7Mo3N duplex stainless steel was performed on a hot simulator. The microstructure of the bonding interface was characterized by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The mechanical properties of the specimen were investigated by a shear strength test. The results indicated that the shear strength was improved with the increase of superplastic deformation reduction. When the deformation reduction was up to 50%, the shear strength of the specimen achieved 417 Mpa, approaching to that of the base metal. In addtion, the superplastic diffusion bonding technique was not very sensitive to surface roughness levels. When the surface roughness of the bonding specimen surpassed 0.416 ?m (level G2), the shear strength achieved at least 381 MPa.

Chen, Xiao-hui; Ren, Xue-ping; Xu, Hui; Tong, Jian-guo; Zhang, Hai-yan

2012-04-01

201

Resulting strength and hardness properties after prior cyclic loading with superimposed incremental deformation of austenitic steel  

International Nuclear Information System (INIS)

This paper covers the results obtained from experimental investigations into the stress/strain behaviour of niobium stabilised stainless steel piping material with the German notation X 6 CrNiNb 18 10, which is similar to AISI 347. From specimens tested in uniaxial experiments it could be proved that, independent of the size of the increment in strain and the cyclic strain range, a limited amount of applied, incremental, prior deformation reduced the overall capability to undergo deformation only by the amount of the accumulated, prior deformation. A clear relationship was observed between the level of prior deformation and the change in hardness. (authors)

202

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

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

2012-02-01

203

Corrosion sensitization behavior and mechanical properties of liquid-nitrogen-deformed austenitic 304 stainless steel  

Science.gov (United States)

Plastic deformation of 304 stainless steel at liquid nitrogen temperature ({-}196sp°C) produces an almost complete transformation to strain-induced alphasp'/-martensite which provides the necessary conditions for a pseudo-recrystallization of the microstructure. This "so-called" pseudo-recrystallization results directly from the martensitic reversion (i.e. martensite to austenite reverse transformation) upon the application of heat treatment within the sensitization temperature range. The very fine duplex (alpha/gamma) microstructure which results (after heat treatment-0.1h-670sp°C) is also accompanied by a very extensive and homogeneous precipitation of chromium-rich carbides. The concomitant pseudo-recrystallization and precipitation processes not only have a profound positive effect on the sensitization behavior, but also affect the mechanical properties of the material. This suggests that 304 stainless steel could be thermo-mechanically treated, to in essence, heal itself and simultaneously produce an extremely fine (?0.1mum) duplex grain structure with intermixed carbides to form a very high strength product. This might have important practical implications since 304 stainless steel is the material of choice in many engineering applications. Electrochemical testing, transmission electron microscopy, scanning electron microscopy, optical microscopy, neutron diffraction, X-ray diffraction, and mechanical testing were some of the techniques employed in this work.

Maldonado, Julio Gerardo

204

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

Directory of Open Access Journals (Sweden)

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.

Langdon, T. G.

2008-12-01

205

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

Directory of Open Access Journals (Sweden)

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.

Anibal Andrade Mendes Filho

2012-02-01

206

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

Science.gov (United States)

The best p-type skutterudites with ZT > 1.1 so far are didymium (DD) filled, Fe/Co substituted, Sb-based skutterudites. DD0.68Fe3CoSb12 was prepared using an annealing-reacting-melting-quenching technique followed by ball milling and hot pressing. After severe plastic deformation via high-pressure torsion (HPT), no phase changes but particular structural variations were achieved, leading to modified transport properties with higher ZT values. Although after measurement-induced heating some of the HPT induced defects were annealed out, a still attractive ZT-value was preserved. In this paper we focus on explanations for these changes via TEM investigations, Raman spectroscopy and texture measurements. The grain sizes and dislocation densities, evaluated from TEM images, showed that (i) the majority of cracks generated during high-pressure torsion are healed during annealing, leaving only small pores, that (ii) the grains have grown, and that (iii) the dislocation density is decreased. While Raman spectra indicate that after HPT processing and annealing the vibration modes related to the shorter Sb-Sb bonds in the Sb4 rings are more affected than those related to the longer Sb-Sb bonds, almost no visible changes were observed in the pole intensity and/or orientation. PMID:25556702

Rogl, Gerda; Grytsiv, Andriy; Bursik, Jiri; Horky, Jelena; Anbalagan, Ramakrishnan; Bauer, Ernst; Mallik, Ramesh Chandra; Rogl, Peter; Zehetbauer, Michael

2015-01-21

207

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

Science.gov (United States)

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.

Szombathelyi, V.; Krallics, Gy

2014-08-01

208

Microstructural evolution and mechanical properties of high strength magneisum alloys fabricated by deformation processing  

Science.gov (United States)

The goal of this research was to develop high strength Mg by thermo-mechanical processing. Several novel techniques were developed to impart large plastic strains on Mg alloys and Mg based composites. The main emphasis of this work was on investigating the effect of different processing schemes on grain-refinement and texture modification of processed material. The room-temperature and elevated-temperature mechanical behavior of processed-Mg was studied in detail. Biaxial corrugated pressing, also known as alternate biaxial reverse corrugation processing was applied to twin-roll cast AZ31 Mg and warm-extruded ZK60 Mg. Friction stir processing to partial depths was applied to thixomolded AM60 Mg and warm-extruded ZK60 Mg. A new process called "bending reverse-bending", was developed and applied to hot rolled AZ31-H24 Mg. A Mg/Al laminated composite was developed by hot pressing and rolling. In processed condition, Mg alloys exhibit enhancement in room-temperature strength and ductility, as well as elevated temperature formability. It was concluded that improvement in mechanical properties of processed-Mg is strongly influenced by grain size and precipitates; while ductility largely depends on resulting deformation textures.

Mansoor, Bilal

209

High-spin isomers, residual interactions and octupole correlations in the N=128 isotones: 211Bi, 212Po and 213At  

International Nuclear Information System (INIS)

Despite the fact that 208Pb is probably the best example of a shell model nucleus, little is known about its high-spin states and those of its nearest neighbours, primarily because of the experimental difficulties involved in populating neutron-rich nuclei. The high-spin states formed from the valence orbitals are important since they provide the building blocks from which more complex configurations can be calculated. The same orbitals are involved in particle-octupole vibrational coupling which presumably evolves into octupole deformation in heavier nuclei. In this paper we present the results of recent measurements which have used a range of reaction techniques to access states in the N = 128 isotones, 211Bi, 212Po and 213At. The results may contribute to the understanding of the structure of the ? = 65 s isomer in 212Po. The new states identified include a J? = (49/2)+, ? = 65 ?s isomer in 213At which decays via an enhanced E3 transition whose strength is influenced by blocking

210

Mechanical properties and deformation behavior of Ti-5Cr-xFe alloys  

International Nuclear Information System (INIS)

The effects of iron on the mechanical properties and deformation behavior of a Ti-5Cr-based system were studied with emphasis on improving the strength/modulus ratio. As-cast Ti-5Cr and a series of Ti-5Cr-xFe (x = 0.1, 0.5, 1, 3 and 5 mass%) alloys prepared by using a dental cast machine were investigated. X-ray diffraction (XRD) for phase analysis was conducted with a diffractometer. Three-point bending tests were performed to evaluate the mechanical properties of all specimens. The fractured surfaces were observed by using scanning electron microscopy (SEM). Moreover, the surface morphology of a post-bending unetched specimen was examined by using an optical microscope. The experimental results indicated that only Ti-5Cr-3Fe and Ti-5Cr-5Fe alloys exhibited ductile properties. The bending moduli of the Ti-5Cr-3Fe and Ti-5Cr-5Fe alloys without an ? phase were lower than those of the Ti-5Cr and Ti-5Cr-xFe alloys with an ? phase. The Ti-5Cr-3Fe alloy exhibited highest bending strength/modulus ratios as large as 25.1, being higher than those of commercially pure titanium (c.p. Ti) by 195% and of the Ti-5Cr alloy by 132%. Moreover, the Ti-5Cr-5Fe alloy also had highest ratios as large as 24.6, being higher than those of c.p. Ti by 189% and of the Ti-5Cr alloy by 128%. Furthermore, the elastically recoverable angles of the Ti-5Cr-3Fe (31.5 deg.) and Ti-5Cr-5Fe (29.6 deg.) alloys were greater than those of c.p. Ti (2.7 deg.) by as much as 1067% and 996%, respectively. Theuch as 1067% and 996%, respectively. The optical micrographs indicated that the surfaces of the Ti-5Cr-3Fe and Ti-5Cr-5Fe alloys were covered with many slip bands. In the current search for better implant materials, the low modulus, ductile property, excellent elastic recovery capability and reasonably high strength (or high strength/modulus ratio) ? phase Ti-5Cr-3Fe and Ti-5Cr-5Fe alloys seem to be promising candidates

211

Estimate of double octupole phonon excitation in the Xe + Pb reaction using the coupled channel WKB approximation  

International Nuclear Information System (INIS)

The coupled channel WKB formalism is applied to study the excitation of double octupole phonon states in 208Pb using a beam of 136Xe ions at an energy 20% above the Coulomb barrier. The yield for individual members of the double octupole multiplet is estimated to be about 5% of the yield for the single phonon state. (Auth.)

212

Deformation behavior and mechanical properties of ultrafine-grained titanium processed by equal channel angular pressing  

International Nuclear Information System (INIS)

A comparative analysis is accomplished for regularities of plastic deformation evolution under tension and creep in ultrafine-grained (UFG) commercial titanium and in polycrystalline titanium within a temperature range of 0.2-0.3Tmelt (Tmelt - melting temperature). It is shown that UFG-titanium has a high tendency to plastic deformation localization in the temperature interval of thermal stability of the structure (273-673 K). The influence of structural state, deformation temperature and rate on deformation relief development is studied, agreement between the nature of plastic deformation localization and the stages of UFG-titanium yield curve is found. Physical reasons for a decrease of apparent activation energy value for UFG-titanium creep are discussed

213

Interplay of inertia and deformability on rheological properties of a suspension of capsules  

CERN Document Server

The interplay of inertia and deformability has a substantial impact on the transport of soft particles suspended in a fluid. However, to date a thorough understanding of these systems is still missing and only a limited number of experimental and theoretical studies is available. We combine the finite-element, immersed-boundary and lattice-Boltzmann methods to simulate three-dimensional suspensions of soft particles subjected to planar Poiseuille flow at finite Reynolds numbers. Our findings confirm that the particle deformation and inclination increase when inertia is present. We observe that the Segr\\'e-Silberberg effect is unstable with respect to the particle deformability. Depending on the deformability and strength of inertial effects, inward or outward lateral migration of the particles takes place. In particular, for increasing Reynolds numbers and strongly deformable particles, distinct flow focusing emerges which is accompanied by a non-monotonic behaviour of the apparent suspension viscosity and th...

Krueger, Timm; Harting, Jens

2013-01-01

214

Minus-I quadrupole system for containing aberration-correction octupoles  

International Nuclear Information System (INIS)

Octupoles may be used to correct the third order spherical aberration of quadrupole transport systems. Crosstalk in the coupling of an octupole placed at a given point causes it to add a term with the wrong sign in the y-channel if it has the right sign in the x-channel, thus severely reducing efficiency. It is often convenient to utilize a special correcting section insertion which is seen as a +I transfer matrix by the first order focusing. Within point-to-point thin lens optics we give two-parameter systems with 16 magnets having locations with large S/sub x/ where S/sub y/ = 0 and vice versa for octupole placement

215

Soliton switching in an anisotropic Heisenberg ferromagnetic spin chain with octupole-dipole interaction  

International Nuclear Information System (INIS)

We study the nonlinear spin excitations in a one-dimensional anisotropic Heisenberg ferromagnetic spin chain with octupole-dipole interaction by a semi-classical approach using Glauber's coherent state method combined with the Holstein-Primakoff bosonic representation for the spin operator in the continuum limit. The associated dynamics are governed by a generalized higher-order nonlinear Schroedinger equation. We point out that the presence of a higher-order influence of octupole-dipole interaction in the ferromagnetic medium enhances the magnetization switching process in the nanoscale regime through the flipping of a soliton.

216

High energy component of giant octupole resonance in medium and heavy mass nuclei  

International Nuclear Information System (INIS)

High energy component of giant octupole resonance has been searched for by a (3He, 3He') reaction on sup(90,92)Zr, sup(116,118,120)Sn, 144Sm and 208Pb nuclei at incident energy 110 - 140 MeV. A giant resonance like structure is observed at excitation energy 118A sup(-1/3) MeV systematically in each target and the angular distributions of these new bumps were obtained. Experimental results consisted with L = 3 transfer, and the energy weighted sum rule fractions of 47 - 95% for the octupole transition were exhausted for this resonance. (author)

217

Octupole states in {sup 196}Pt(p,p{sup {prime}}{gamma})  

Energy Technology Data Exchange (ETDEWEB)

Possible octupole states in {sup 196}Pt were studied via the {sup 196}Pt(p,p{sup {prime}}{gamma}) reaction with 12.7 MeV protons. The results considerably strengthen the argument made previously that the low-energy octupole state in {sup 196}Pt is quite fragmented. Furthermore, one of the possible mixed symmetry states previously identified in this nucleus is observed in the present experiment, providing evidence that it has J{sup {pi}}=2{sup +}. {copyright} {ital 1997} {ital The American Physical Society}

Jewell, J.K.; Cottle, P.D.; Kemper, K.W.; Riley, L.A. [Department of Physics, Florida State University, Tallahassee, Florida 32306-3016 (United States)

1997-11-01

218

Measurement of rock-mass deformation properties by the borehole jacking method at the near-surface test facility  

International Nuclear Information System (INIS)

Borehole jacking tests have been conducted in an attempt to estimate the in situ deformation properties of Pomona basalt in the Near-Surface Test Facility (NSTF) on the Hanford Site, Washington. Full-scale heater tests are being conducted there as part of the feasibility study of radioactive waste disposal in basalt. The borehole jacking method obtains directionally oriented modulus values at depth in the rock mass. Seventy-six tests were conducted in two horizontal and four vertical boreholes

219

Plastic deformation effect on ageing kinetics and properties of low-nickel maraging steel  

International Nuclear Information System (INIS)

Strength, fatigue, hardness, impact viscosity and ageing kinetics of 05Kh2N5MFDYu steel have been studied as dependent on conditions of rolling and ageing. It is found that deformation at 900 deg C increases cyclic strength and resistance to brittle failure, but hardly affects static strength. Appreciable strengthening is provided by the following way of processing: ageing at 450 deg C - cold rolling with 30% compression - ageing at 500 deg C. Cold deformation and, to a smaller extent, hot deformation intensify the decomposition of solid solution in course of ulterior ageing, apparently on account of acceleration of diffusion processes

220

Effect of non-uniform deformation on properties of forged circular kilns  

International Nuclear Information System (INIS)

Non-uniformity of deformation was studied in model conditions in circular forged products from austenitic stainless steels. An extensive area with small local deformations was observed around forging edges. The study of samples from the edges and the central part of forgings showed significant differences in the microstructure, yield point and the resistance to intergranular corrosion. The results are shown in tables and graphs. (J.B.)

221

The influence of plastic deformation and heat treatment on microstructure and mechanical properties of W-Ni-Fe alloy  

International Nuclear Information System (INIS)

The paper presents the results of microstructural observations, fractography and tensile tests investigations performed at room temperature on series of 90% W - 7% Ni - 3% Fe alloy specimens representative of 'as sintered state', cold worked (10-40%) and subjected to additional annealing (500-750 oC). Changes in the microstructure have been described quantitatively using a computer sided image analysis and qualitatively by scanning electron microscopy (fractography). Chemical composition changes in micro-areas were investigated by electron probe X-ray microanalysis. The results were correlated with mechanical properties of the alloy. After cold rolling the tungsten particles change their shape from nearly spherical into discs. On the fracture surface of 'as sintered' alloy after tensile test, fracture paths prevail along tungsten interfaces and tungsten-matrix separation. The fracture paths through the matrix have a ductile character. With the increasing plastic deformation, fraction of fracture paths across tungsten particles increases. For the samples subjected to 40% deformation tungsten cleavage is predominant. Simultaneously, ductility of the matrix markedly decreases. The deformation of tungsten particles as well as strain hardening of matrix increases the strength and hardness of WHA. The UTS of the alloy subjected to 40% deformation increases by approximately 42%. The annealing of alloy after cold working at the temperature range of 500-620 ooC increases the UTS to 1565 MPa without changing its elongation to fracture, which remains lower than that in 'as sintered state'. (author)

222

Mechanical properties and atomistic deformation mechanism of ?-Y2Si2O7 from first-principles investigations  

International Nuclear Information System (INIS)

The theoretical mechanical properties and atomistic shear deformation mechanisms of ?-Y2Si2O7, one of the most refractory silicates and potentially useful as a high-temperature structural ceramic, were investigated using first-principles calculations. The material shows low shear moduli to bulk modulus ratios, as well as a low ideal shear strength to tensile strength ratio. The unusual low shear deformation resistance of ?-Y2Si2O7 originates from the inhomogeneous strength of its chemical bonds. The Y-O bond is weaker and readily stretches and shrinks; and Si-O bond is stronger and more rigid. The relative softer YO6 octahedron positively accommodates shear deformation by structural distortion, while the Si2O7 pyrosilicate unit is more resistant to deformation. The reported shear-load-bearing mechanism is quite similar to those found in the 'quasi-ductile' LaPO4 monazite and ternary layered carbides (the so-called MAX phases), and can endow ?-Y2Si2O7 with quasi-ductility and damage tolerance

223

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

International Nuclear Information System (INIS)

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

224

Deformed microstructure and mechanical properties of AM60B magnesium alloy under hypervelocity impact at a velocity of 4 km s{sup -1}  

Energy Technology Data Exchange (ETDEWEB)

Deformed microstructure and mechanical properties of AM60B magnesium alloy under hypervelocity impact at a speed of 4 km s{sup -1} were studied through optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and indenter technique. The results show that the deformed microstructure below the crater can be classified as three zones, i.e. dynamic recrystallization zone, high density deformation twin zone and low density deformation twin zone. The refined and equiaxed recrystallized grains adjacent to the crater were formed, which should be attributed to the twining-induced dynamic recrystallization mechanism. The {l_brace}101-bar 2{r_brace}, {l_brace}101-bar 1{r_brace} deformation twins are confirmed through selected area electron diffraction (SAED) technique. The microhardness and yield strength in the deformed microstructure zone near the crater are much higher than that of the matrix, which should be attributed to strain hardening and grain refining.

Zou, D.L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L., E-mail: lzhen@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhu, Y. [School of Aerospace, Harbin Institute of Technology, Harbin 150001 (China); Xu, C.Y.; Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Pang, B.J. [School of Aerospace, Harbin Institute of Technology, Harbin 150001 (China)

2010-06-15

225

Deformed microstructure and mechanical properties of AM60B magnesium alloy under hypervelocity impact at a velocity of 4 km s-1  

International Nuclear Information System (INIS)

Deformed microstructure and mechanical properties of AM60B magnesium alloy under hypervelocity impact at a speed of 4 km s-1 were studied through optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and indenter technique. The results show that the deformed microstructure below the crater can be classified as three zones, i.e. dynamic recrystallization zone, high density deformation twin zone and low density deformation twin zone. The refined and equiaxed recrystallized grains adjacent to the crater were formed, which should be attributed to the twining-induced dynamic recrystallization mechanism. The {101-bar 2}, {101-bar 1} deformation twins are confirmed through selected area electron diffraction (SAED) technique. The microhardness and yield strength in the deformed microstructure zone near the crater are much higher than that of the matrix, which should be attributed to strain hardening and grain refining.

226

Deformational Structures on Smooth Manifolds  

OpenAIRE

Deformational structures, in many aspects generalizing standard elasticity theory, are investigated in abstract form. Within free deformational structures we define algebra of deformations, classify them by its special properties, define motions and conformal motions together with deformational decomposition of manifolds, generalizing isometry of Riemannian spaces and consider some physical examples. In frame of dynamical deformational structures we formulate variational pro...

Kokarev, Sergey S.

2002-01-01

227

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

International Nuclear Information System (INIS)

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

228

Effect of multiaxial deformation Max-strain on the structure and properties of Ti-Ni alloy  

Science.gov (United States)

The severe plastic deformation (SPD) forming ultrafine-grained (nanocrystalline or nanosubgrained) structure is one of the most effective ways to improve the functional properties of Ti-Ni-based shape memory alloys [1, 2]. In the present work, the SPD of near-equiatomic Ti-Ni alloy was carried out using the multi-axial deformation module Max-strain, which is a part of the physical simulation system "Gleeble 3500". The deformation was performed at a constant temperature of 400°C with speed of 0.5 mm/s in six passes without interpass pauses. The accumulated true strain was about 3. As a result, a mixed ultrafine-grained/subgrained structure with grain/subgrain sizes from 50 to 300 nm and a high density of free dislocations formed. The resulting structure is close to a nanoscale region and provides a significant advantage in the basic functional property - completely recoverable strain - as compared with a conventional recrystallized structure: 7% versus 2%.

Khmelevskaya, I. Yu; Kawalla, R.; Prokoshkin, S. D.; Komarov, V. S.

2014-08-01

229

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

International Nuclear Information System (INIS)

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.

230

Green function theory of a Heisenberg ferromagnet with dipole-octupole interactions  

International Nuclear Information System (INIS)

The effect of dipole-octupole interaction on different magnetic parameters for the spin S=3/2 system in the presence of biquadratic exchange has been investigated. The Green function technique with random phase approximation (RPA) has been employed to obtain analytical results. These results are in good agreement with the results of the molecular field approximation (MFA). (orig.)

231

Octupole coil configuration for the Tandem Mirror Experiment Upgrade (TMX-U)  

International Nuclear Information System (INIS)

The octupole plug concept offers the attractive possibility of reducing the length of the plug and transition sections in tandem mirror reactors. In the Tandem Mirror Experiment Upgrade (TMX-U), we are designing an octupole plug-transition that will replace our current quadrupole plug-transition. The reduction in length is made possible by the more nearly circular plasma cross section throughout the plug and transition sections. The principal physics of the design is the magnetohydrodynamic (MHD) stabilization of the core plasma in the plug by a hot electron ring in the mantle region surrounding the core. This hot electron mantle is MHD stable because of the good curvature field lines provided by the octupole. The positive radial pressure gradient in the hot electron mantle in turn stabilizes the core's plasma. Each octupole set consists of six coils replacing the transition and plug sets in the existing TMX-U experiment. The central cell coils will remain unchanged. Five of the coils for each of the new sets will be fabricated, while one, the 6-T mirror coil, will be reused from TMX-U. This paper will elaborate on the design configuration of the magnets. In particular, the configuration provides for adequate neutral beam lines-of-sight, and access for 0.615 MW of electron-cyclotron resonant heating (ECRH) on each end

232

Investigations of the properties of filled elastomers during cyclic deformation using small angle x-ray scattering  

Science.gov (United States)

In this work small angle x-ray scattering (SAXS) and a new reverse Monte Carlo (RMC) technique were used to characterize the evolution of filler structure in silica-filled polydimethylsiloxane and polydimethyldiphenylsiloxane elastomers. Elastomers are soft, brittle, and have poor fatigue properties. The addition of filler particles, usually carbon black or fumed metal oxides, greatly increases the toughness, maximum elongation, tensile strength, stiffness, and fatigue resistance. Small angle x-ray scattering with in situ mechanical testing provides a way to directly measure structural changes during deformation that have proved difficult to measure using traditional microscopy techniques. Traditional analytical techniques as well as a new reverse Monte Carlo (RMC) method were used to provide insight into the nature of the structural changes during deformation. During deformation the filler particles form raft-like structures that are aligned with their long axes perpendicular to the tensile axis. These structures separate in an affine matter with the sample extension ratio until a critical extension ratio is reached that is independent of silica surface treatment. At extensions above the critical extension ratio the rafts maintain the same relative spacing despite an increasing sample extension ratio. Above the critical extension Poisson compression combined with a high bulk modulus appears to breakup and deform the rafts. During unloading from extension ratios above the critical extension ratio the rafts show a less ordered structure and eventually return to their initial structure when completely unloaded. The patterns for the samples with high particle-filler adhesion show that the filler rich regions are disoriented by rotation. On subsequent cycles there is less correlated orientation between filler particles up to the point of previous maximum extension ratio. Above that extension ratio the structure is identical to that of a monotonically deformed sample. This provides a partial explanation for the strain softening phenomena known as the Mullins effect.

Scholz, Arthur K.

233

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

International Nuclear Information System (INIS)

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.

234

Tests for development of estimation technology of reactor core deformation. Report No.1: fundamental mechanical properties of wrapper tube (test report)  

International Nuclear Information System (INIS)

Mechanical properties such as local contact compression stiffness, bending stiffness, deformation properties, material properties, and friction properties of a wrapper tube structure were clarified experimentally, which can be used as the basic data for development of estimation technology of reactor core deformation. Contents of the Tests data as follows: (1) Effects of load supporting boundary conditions, whether or not a contact-proof pad is attached, and length of duct, on cross section deformation of wrapper tube were made clear as the local contact compression stiffness characteristics. (2) Bending stiffness does not depend on the difference of load supporting boundary conditions. The property of cross section deformation under bending load was obtained. (3) The deformation modes and the strain distributions were obtained by the deformation tests of wrapper tube. (4) The stress-strain diagrams including plastic range under various strain variation rates were obtained by the material tests at room temperature. (5) The static and the dynamic friction coefficients by various contact angles and the contact loads between contact-proof pads of two wrapper tubes were obtained by friction property tests. (author)

235

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

Energy Technology Data Exchange (ETDEWEB)

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.

Simunovic, S

2003-09-23

236

Study of transition nuclei deformation. Study of shape transformation mechanisms and rigidity properties of these nuclei  

International Nuclear Information System (INIS)

The deformation of transition nuclei has been studied by means of a rotor plus particle model, where the Fermi level lies at the beginning or at the end of high j subshells, the observation of high spin collective states gives the sign of the deformation. These states, selectively populated in (heavy ions-xn) reactions, have been studied by their gamma decay. The limits of the model have been studied. Near closed shells, it is a weak coupling model which is relevant. Large deformations (? approximately equal to 0.3) have been proposed in nuclei of the g 9/2 region. In the transition region Z<82, the experimental results suggest a localization of the wave functions in spite of a soft potential. Mechanisms of shape transitions have been found. Coriolis effect on core nucleons has been discussed

237

Influence of plastic deformation on superconducting properties of V3Si single crystals  

International Nuclear Information System (INIS)

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)

238

Symmetry of the CMB sky as a new test of its statistical isotropy. Non cosmological octupole?  

International Nuclear Information System (INIS)

In this article we propose a novel test for statistical anisotropy of the CMB ?T( n-circumflex = (?,?)). The test is based on the fact, that the Galactic foregrounds have a remarkably strong symmetry with respect to their antipodal points with respect to the Galactic plane, while the cosmological signal should not be symmetric or asymmetric under these transitions. We have applied the test for the octupole component of the WMAP ILC 7 map, by looking at a3,1 and a3,3, and their ratio to a3,2 both for real and imaginary values. We find abnormal symmetry of the octupole component at the level of 0.58%, compared to Monte Carlo simulations. By using the analysis of the phases of the octupole we found remarkably strong cross-correlations between the phases of the kinematic dipole and the ILC 7 octupole, in full agreement with previous results. We further test the multipole range 2 < l < 100, by investigating the ratio between the l+m = even and l+m = odd parts of power spectra. We compare the results to simulations of a Gaussian random sky, and find significant departure from the statistically isotropic and homogeneous case, for a very broad range of multipoles. We found that for the most prominent peaks of our estimator, the phases of the corresponding harmonics are coherent with phases of the octupole. We believe, our test would be very useful for detections of various types of residuals of the foreground and systematic effects at a very broad range of multipoles 2 ? l ? 1500?3000 for the forthcoming PLANCK CMB map, before any conclusions about primordial non-Gaussianity and statistical anisotropy of the CMB

239

Effect of temperature and rate of deformation on mechanical properties in 15Kh5M steel  

International Nuclear Information System (INIS)

Results of tensile tests carried out for specimens of steel at the temperatures of 293...973 K and deformation rates of 8.33 (10-3...10-7) c-1 are presented. It is shown that testing conditions affect the strength and ductility characteristics for the 15Kh5M steel. Dependences of the ductility characteristics are of v-like form. Minima of all v-like curves of the uniform component of the relative elongation are at 773 K. A decrease in the deformation rate results in the growth of the relative elongation and its uniform component as well as of a zone of deformation localization in the region of the specimen neck. A considerable local plastic deformation is shown to precede a failure of the 15Kh5M steel pipe under conditions of operation. A low sensitivity of 15Kh5M steel to a stress concentration within the temperature range of 293...843 K is established

240

Effect of helium on mechanical properties, energy accumulation and dissipation at ARMCO iron deformation  

International Nuclear Information System (INIS)

Study of mechanical and energy parameter changes at tension of ARMCO iron samples with implanted helium (10-3 at %) was studied. Effect of helium on strength, plasticity, latent energy and deformation in 293...473 K temperature range was considered

241

Classical bifurcation and enhancement of quantum shells: Systematic analysis of reflection-asymmetric deformed oscillator  

International Nuclear Information System (INIS)

The correspondence between classical periodic orbits and quantum shell structure is investigated for a reflection-asymmetric deformed oscillator model as a function of quadrupole and octupole deformation parameters. The periodic orbit theory reveals several aspects of quantum level structure for this non-integrable system. Good classical-quantum correspondence is obtained in the Fourier transform of the quantum level density, and the importance of periodic orbit bifurcation is demonstrated. A systematic survey of the local minima of shell energies in the two-dimensional deformation parameter space shows that prominent shell structures do emerge at finite values of the octupole parameter. Correspondences between the regions exhibiting strong shell effects and the classical bifurcation lines are investigated, and the significance of these bifurcations is indicated. (orig.)

242

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

International Nuclear Information System (INIS)

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 ampThe 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

243

Microstructures and properties of ultrafine-grained pure titanium processed by equal-channel angular pressing and cold deformation.  

Science.gov (United States)

Equal-channel angular pressing (ECAP) has been used to refine the grain size of commercially pure (CP) titanium as well as other metals and alloys. CP-Ti is usually processed at about 400 degrees C because it lacks sufficient ductility at lower temperature. The warm processing temperature limits the ability of the ECAP technique to improve the strength of CP-Ti. We have employed cold deformation following warm ECAP to further improve the strength of CP-Ti. Ti billets were first processed for eight passes via ECAP route Bc, with a clockwise rotation of 90 degrees between adjacent passes. The grain size obtained by ECAP alone is about 260 nm. The billets were further processed by cold deformation (cold rolling) to increase the crystalline defects such as dislocations. The strength of pure Ti was improved from 380 to around 1000 MPa by the two-step process. This article reports the microstructures, microhardness, tensile properties, and thermal stability of these Ti billets processed by a combination of ECAP and cold deformation. PMID:12914057

Stolyarov, V V; Zhu, Y T; Lowe, T C; Valiev, R Z

2001-06-01

244

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

International Nuclear Information System (INIS)

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

245

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

Science.gov (United States)

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.

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

2013-05-01

246

Coulomb excitation of deformed nuclei  

International Nuclear Information System (INIS)

Coulomb excitation method is applied to an investigation of the band structure in the deformed nucleus. A multi-Ge detector system, NORDBALL, and Si position sensitive detectors were used for the present experiments. Coulomb excitation of 154Sm, 158Gd and 160Gd were performed by using the 32S, 48Ti and 58Ni beams. The ground-state band was excited up to the 16+ state by the 58Ni beam, and a few side bands, i.e. the beta band, the gamma band and one or two octupole bands of K=0- and 1-, were excited in each nucleus. In addition, a new band with the spins and parities of (4+), 6+, 8+, 10+, 12+ and (14+) was found in 154Sm. (author)

247

Deformation properties of Al-Mg alloy 5086 in laboratory and explosive tests  

Energy Technology Data Exchange (ETDEWEB)

Static and dynamic deformation test results were obtained for Al-Mg alloy 5086 material in various conditions in order to provide a constitutive equation for use in code computations of more complex explosive deformations. Conventional laboratory tensile tests showed interference of a reversed strain rate effect because of dynamic strain aging (DSA). The DSA behavior was confirmed for additional material conditions spanning the mechanical and thermal H32 processing treatment of as-supplied pipe stock. Influences of grain size and H32 treatment on yielding and subsequent strain hardening behaviors were evaluated. Split-Hopkinson pressure bar test results on related Al-Mg alloy 5083 material were employed in the determination of applicable constants in Zerilli-Armstrong (Z-A) constitutive equations. Use of the equations is reported here for description of shock-induced bulging of a water-filled pipe material in hydrocode validation tests. (orig.)

Armstrong, R.W.; Erickson-Natishan, M.A.; Wagenhofer, M. [Maryland Univ., College Park, MD (United States). Dept. of Mechanical Engineering; Chambers, G.P.; Sandusky, H.W.; Zerilli, F.J.

2000-07-01

248

Enhancement of nuclear Schiff moments and time reversal violation in atoms due to soft nuclear octupole vibrations  

OpenAIRE

Parity and time invariance violating (${\\cal P},{\\cal T}$-odd) nuclear forces produce ${\\cal P},{\\cal T}$-odd nuclear moments, for example, the nuclear Schiff moment. In turn, this moment can induce electric dipole moments (EDMs) in atoms. We estimate the contribution to the Schiff moment from the soft collective octupole vibrations existing in many heavy nuclei. Two possible mechanisms are considered, mixing of the ground state of an odd-$A$ nucleus with the octupole phonon...

Flambaum, V. V.; Zelevinsky, V. G.

2002-01-01

249

Optical properties of plastically deformed copper: amorphous state with residual nanocrystals  

OpenAIRE

Chemically pure copper (99.99) prepared in a sample of square cross-section (10*10 mm2) and about 50 mm long was extremely plastically deformed with the repeated application of Equal Channel Angular Pressing. AFM investigation gives us information on microstructure with ultrafine grains. The structure ofthe sample surface, such as the copper oxide and surface roughness over-layer, registered by ellipsometry. Two types of lines are registered by Raman spectroscopy: narrow, with the width ~ 7 c...

Rudolf, Rebeka; Gilic?, M.; Romc?evic?, M.; Anz?el, Ivan

2012-01-01

250

E4 properties in deformed nuclei and the sdg interacting boson model  

International Nuclear Information System (INIS)

The hexadecapole transition strength distribution is measured for the deformed nucleus /sup 150/Nd using the (p,p') reaction at E/sub p/ = 30 MeV. The experimental information on B(E4) values in this nucleus and in /sup 156/Gd is interpreted in the framework of the sdg interacting boson model. It is found that the main features of the experimental data are fairly well reproduced by a Hartree-Bose method plus Tamm-Dancoff approximation

251

Systematics of nuclear densities, deformations and excitation energies within the context of the generalized rotation-vibration model  

International Nuclear Information System (INIS)

We present a large-scale systematics of charge densities, excitation energies and deformation parameters for hundreds of heavy nuclei. The systematics is based on a generalized rotation-vibration model for the quadrupole and octupole modes and takes into account second-order contributions of the deformations as well as the effects of finite diffuseness values for the nuclear densities. We compare our results with the predictions of classical surface vibrations in the hydrodynamical approximation.

252

Systematics of nuclear densities, deformations and excitation energies within the context of the generalized rotation-vibration model  

Energy Technology Data Exchange (ETDEWEB)

We present a large-scale systematics of charge densities, excitation energies and deformation parameters for hundreds of heavy nuclei. The systematics is based on a generalized rotation-vibration model for the quadrupole and octupole modes and takes into account second-order contributions of the deformations as well as the effects of finite diffuseness values for the nuclear densities. We compare our results with the predictions of classical surface vibrations in the hydrodynamical approximation.

Chamon, L.C., E-mail: luiz.chamon@dfn.if.usp.b [Departamento de Fisica Nuclear, Instituto de Fisica da Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo, SP (Brazil); Carlson, B.V. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Centro Tecnico Aeroespacial, Sao Jose dos Campos, SP (Brazil)

2010-11-30

253

Effects of annealing temperature and time on the microstructural evolution and corresponding mechanical properties of 5083 Al alloy deformed at cryogenic and room temperatures  

Energy Technology Data Exchange (ETDEWEB)

The effects of annealing temperature and time in 5083 Al alloy deformed at cryogenic temperature were investigated and compared with alloys deformed at room temperature. It was found that mechanical properties of deformed and annealed alloys were mainly influenced by the volume fraction of recrystallized grains. The formation of a bimodal microstructure, consisting of equiaxed grains and elongated subgrains, seems to be responsible for the good combination of uniform elongation and tensile strength. Additionally, the small variation of hardness for annealing temperatures of 300-400 C indicates that mechanical properties of 5083 Al alloy deformed and annealed are significantly influenced by the volume fraction of recrystallized grains rather than by the coarsening of recrystallized grains. (orig.)

Song, H.R.; Nam, W.J. [Dept. of Materials Science and Engineering, Kookmin Univ., Seoul (Korea)

2005-03-01

254

The long-term strength and deformation properties of crystalline rock in a high level nuclear waste repository  

International Nuclear Information System (INIS)

The time-dependent phenomena which can affect the strength and deformation properties of hard crystal line rock are clarified. Suitable measuring methods for field conditions are also summarized. The significance of time is evaluated around a shaft in a high level nuclear waste repository. According to the investigation it is generally held that creep and cyclic fatigue are the most important phenomena. They arise from subcritical crack growth which is most affected by stress intensity, chemical environment, temperature, and microstructure. There are many theoretical models, which can be used to analyse creep and cyclic fatigue, but they are defective in describing the triaxial stress condition and strength criteria. Additionally, the required parameters are often too difficult to determine with adequate accuracy. The joint creep rate depends on the affecting stress regime, on the water conditions, and on the properties of filling material. The acoustic emission method is suited to observe long-term microcrack development in field conditions. The computer program developed by Atomic Energy of Canada Limited (AECL) is used to evaluate the time-dependent de-formation around a main shaft. According to the model the enlargement of the shaft radius by 30 cm takes millions of years. The possible reduction of shaft radius by 3 mm will happen during 200 years. The model is very sensitive to changes in stress state, in the uniaxial compressive strength, and in the stress corrosion index

255

Effect of V and Nb additions on microstructure, properties, and deformability of Ti-45Al-9 (V, Nb, Y alloy  

Directory of Open Access Journals (Sweden)

Full Text Available Ti-45Al-9(V, Nb, Y alloys with four different x=V/Nb (atomic ratio x = 1, 1.5, 2 and 3.5 have been prepared, and the microstructures, properties and hot deformation behaviors were investigated. SEM, XRD and TEM results showed that Ti-45Al-9(V, Nb, Y alloys were mainly composed of ?, ?2, and ? phase, and the volume fraction of ? phase increased with the increase of the atomic ratio of V/Nb. The alloys were featured with lamellar microstructure with ? and ? phases locating at the colony boundaries, and some ? precipitates appearing at ?/? interfaces. It was found that the colony size decreased with the increase of x. The alloys exhibited moderate mechanical properties at room temperature, with a yield strength of over 600 MPa, and fractures showed mainly translamellar character. The alloy with x=3.5 exhibited the best deformability at elevated temperature and that with x=1 had superior oxidation resistance at 800 ?.

Yang Fei

2010-11-01

256

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

International Nuclear Information System (INIS)

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.)

257

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

Energy Technology Data Exchange (ETDEWEB)

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 ferrite–martensite 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.

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

2014-02-24

258

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

International Nuclear Information System (INIS)

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 ferrite–martensite 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

259

Structure and mechanical properties of iron subjected to surface severe plastic deformation by attrition: II. Mechanical properties of nano- and submicrocrystalline iron  

Science.gov (United States)

Depth-sensing indentation is used to study the effect of grain refinement to submicro- and nanograins on the mechanical properties (hardness, plasticity, Young’s modulus) of armco iron subjected to severe plastic deformation by attrition in argon. In contrast to fcc metals, where the hardness increases and the plasticity decreases as the grain size decreases to 20 nm, the hardness of bcc iron decreases from 5.8 to 3.7 GPa and plasticity ? A increases from 0.82 to 0.87 as the grain size decreases from 50 to 20 nm.

Yurkova, A. I.; Milman, Yu. V.; Byakova, A. V.

2010-04-01

260

Structure and mechanical properties of iron subjected to surface severe plastic deformation by friction: I. Structure formation  

Science.gov (United States)

The severe plastic deformation of armco iron by friction is experimentally studied, and the results obtained are used to show that efficient grain refinement is possible in the temperature ranges of warm and hot deformation. A nanocrystalline structure forms only under dynamic recrystallization conditions during hot deformation, which is ensured by deformation in different directions at a rate higher than 102 s-1.

Yurkova, A. I.; Milman, Yu. V.; Byakova, A. V.

2010-04-01

261

Investigation of octupole vibrational states in 150Nd via inelastic proton scattering (p,p'g)  

CERN Document Server

Octupole vibrational states were studied in the nucleus $^{150}\\mathrm{Nd}$ via inelastic proton scattering with $\\unit[10.9]{MeV}$ protons which are an excellent probe to excite natural parity states. For the first time in $^{150}\\mathrm{Nd}$, both the scattered protons and the $\\gamma$ rays were detected in coincidence giving the possibility to measure branching ratios in detail. Using the coincidence technique, the $B(E1)$ ratios of the decaying transitions for 10 octupole vibrational states and other negative-parity states to the yrast band were determined and compared to the Alaga rule. The positive and negative-parity states revealed by this experiment are compared with Interacting Boson Approximation (IBA) calculations performed in the (spdf) boson space. The calculations are found to be in good agreement with the experimental data, both for positive and negative-parity states.

Elvers, M; Ahmed, T; Ahn, T; Anagnostatou, V; Cooper, N; Deng, C; Endres, J; Goddard, P; Heinz, A; Ilie, G; Jiang, E; Kueppersbusch, C; Radeck, D; Savran, D; Shenkov, N; Werner, V; Zilges, A

2011-01-01

262

High spin octupole correlations in the N=85, 139Xe and 141Ba isotones  

International Nuclear Information System (INIS)

High spin states in 139Xe and 141Ba have been investigated using ?-? - and ?-?-?-coincidence studies of spontaneous fission of 252Cf. Alternating parity bands built on a 7/2-level are assigned up to spin I=(37/2) and I=(29/2) in 139Xe and 141Ba, respectively. Another possible octupole band based on ?i132(f7/2)2 multiplet with spin up to (29/2) also is observed in both nuclei. Cascades of enhanced E1 transitions and B(E1)/B(E2) ratios indicate strong octupole correlations. Systematics of the ?(f7/2)3, ?(f7/2)3x3- and ?u13/2(f7/2)2 multiplets and bands in N 85 isotones are presented. (author). Letter-to-the-editor

263

Octupole excitations in vibrational nuclei and the sdf interacting boson model  

Energy Technology Data Exchange (ETDEWEB)

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{sup -} states, exhibit a dependence on the ratio of valence particle numbers and indicate that a IBM-2 approach might be more appropriate. (orig.).

Pignanelli, M.; Blasi, N.; Micheletti, S. (Milan Univ. (Italy). Dipt. di Fisica Istituto Nazionale di Fisica Nucleare, Milan (Italy)); De Leo, R. (Lecce Univ. (Italy). Dipt. di Fisica Istituto Nazionale di Fisica Nucleare, Lecce (Italy)); Hofstee, M.A.; Schippers, J.M.; Werf, S.Y. van der (Rijksuniversiteit Groningen (Netherlands). Kernfysisch Versneller Inst.); Harakeh, M.N. (Vrije Univ., Amsterdam (Netherlands). Faculteit Natuurkunde en Sterrekunde)

1990-12-10

264

Octupole excitations in vibrational nuclei and the sdf interacting boson model  

International Nuclear Information System (INIS)

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.)

265

Indication for a K/sup ?/ = 0- octupole band in 150Nd from electron scattering  

International Nuclear Information System (INIS)

Recent electron scattering results on the 0.850 MeV level of 150Nd, when analyzed in terms of the interacting boson model, are inconsistent with the interpretation of this level as a pure J/sup ?/(K) = 2+(0) state. Very recent (n,n'?) work has shown this level to be a 1-, 2+ doublet. Assuming this level to be the band head of a ''K/sup ?/ = 0-'' octupole band, a simple model is used to predict electron scattering form factors for the 0.850 MeV state and a 3- octupole level observed at 0.931 MeV. Comparison is made between these predicted form factors and recent electron scattering data

266

A practical method for constructing N-quadrupole- and N-octupole-phonon states  

International Nuclear Information System (INIS)

A method for constructing wave functions of the quadrupole and octupole oscillator is given. The obtained states have good seniority and are similar to the ones constructed by previous methods. Although the method is not based upon group-theoretical principles, the internal labels appearing either in the chain R(5) is contained in R(3) or in the chain R(7) is contained in R(3) can be used for the classification of the constructed states. (Auth.)

267

Nanoindentation and deformation properties of nanoscale silicon carbide films on silicon substrate  

Science.gov (United States)

We propose a model to describe the microhardness of a nanoscale film-substrate system as a function of the depth of indenter penetration. The proposed model has been used to study the deformation characteristics of a nanometer-thick silicon carbide (SiC) grown on a silicon substrate by the method of atomic substitution. The microhardness of as-grown SiC film and a modified silicon layer has been determined. The SiC film thickness has been determined using the nanoindentation technique. The data of nanoindentation are in good agreement with the results of ellipsometric measurements.

Grashchenko, A. S.; Kukushkin, S. A.; Osipov, A. V.

2014-12-01

268

E4 properties in deformed nuclei and the sdg interacting boson model  

Energy Technology Data Exchange (ETDEWEB)

The hexadecapole transition strength distribution is measured for the deformed nucleus /sup 150/Nd using the (p,p') reaction at E/sub p/ = 30 MeV. The experimental information on B(E4) values in this nucleus and in /sup 156/Gd is interpreted in the framework of the sdg interacting boson model. It is found that the main features of the experimental data are fairly well reproduced by a Hartree-Bose method plus Tamm-Dancoff approximation.

Wu, H.C.; Dieperink, A.E.L.; Scholten, O.; Harakeh, M.N.; De Leo, R.; Pignanelli, M.; Morrison, I.

1988-10-01

269

Blocking of octupole correlations deduced from the decay of multiparticle isomer in 212 At  

International Nuclear Information System (INIS)

The importance of particle-octupole vibrational interactions for heavy nuclei arises because of the presence of a large number of orbitals with the angular momentum differences ?j=?1=3 For simple one-particle excitations the coupling involves specific proton or neutron orbitals, but when both proton and neutron orbits are involved, non-linear couplings lead to even more dramatic effects, as occurs for example when high spin states are formed by the aligned spins of a few valence protons and neutron orbits occupied following core excitation. High spin isomeric states close to the yrast line which de-excite via very strong E3 transitions result, and the last few years have seen a detailed understanding of the development of their structure as one moves away from the 208Pb core. Recent measurements have been able to determine the extent to which excitations into single particle orbits, which are major components of the octupole vibrational state in a microscopic description, result in a blocking of the octupole correlation. Angular distribution, ?-?-time, ?-time, and conversion electron measurements were performed using the 208Pb(7Li,3n)212At reaction with beams from the ANU Heavy-Ion facility

270

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

271

Orientation dependence of the cyclic deformation properties of niobium single crystals  

International Nuclear Information System (INIS)

Niobium single crystals of seven different orientations have been deformed cyclically in tension-compression over a range of total axial strain amplitudes between 0.3 x 10-3 and 6.0 x 10-3 at room temperature and at a constant total strain rate of 6.0 x 10-4 s-1. It has been found that the cyclic work hardening is strongly dependent on the orientation of the stress axis, and that, for some orientations, the cyclic stress strain curve depends on the cyclic strain history especially at small strain amplitudes. The stress asymmetry observed in the peak stress has been discussed in terms of the sign of the stress components on brace 112 brace and brace 110 brace planes. For some orientations the initial circular cross-section of the specimens became elliptical with deformation. These changes in shape have been found to be in good quantitative agreement with those predicted from the slip asymmetry. (author)

272

Influence of severe plastic deformation on the structure and properties of ultrahigh carbon steel wire  

Energy Technology Data Exchange (ETDEWEB)

Ultrahigh-carbon steel wire can achieve very high strength after severe plastic deformation, because of the fine, stable substructures produce. Tensile strengths approaching 6000 MPa are predicted for UHCS containing 1.8%C. This paper discusses the microstructural evolution during drawing of UHCS wire, the resulting strength produced and the factors influencing fracture. Drawing produces considerable alignment of the pearlite plates. Dislocation cells develop within the ferrite plates and, with increasing strain, the size normal to the axis ({lambda}) decreases. These dislocation cells resist dynamic recovery during wire drawing and thus extremely fine substructures can be developed ({lambda} < 10 nm). Increasing the carbon content reduces the mean free ferrite path in the as-patented wire and the cell size developed during drawing. For UHCS, the strength varies as {lambda}{sup {minus}5}. Fracture of these steels was found to be a function of carbide size and composition. The influence of processing and composition on achieving high strength in these wires during severe plastic deformation is discussed.

Leseur, D R; Sherby, O D; Syn, C K

1999-07-01

273

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

274

Influence of severe plastic deformation by the ECAP method on structure and properties of the P2-04BCh steel  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Maim aim of this paper is to describe the plastic deformation executed by ECAE of low carbon steel. The ECAE method lead to significant improvement of strength of investigated material.Design/methodology/approach: Experiments were planned and realised an the temperature ranging from room temperature up 280oC. After application of deformation the structure was investigated in dependence on accumulation of deformation and deformation temperature as well as abovementioned final properties.Findings: Accumulated deformation varied from the value 2 to 8. Investigation of structure by electron microscopy was made with use microscope JEOL JEM 2100. Mechanical properties were investigated by tensile test. Statistic evaluation of angular disorientation and of size of grains/sub-grains was also made with use of electron diffraction (EBSD in combination with scanning electron microscope FEG SEM Philips.Practical implications: The technology ECAE was applied on low carbon steel. It was verification of ECAE application possibility on steel P2-04BCH importantly for following applying on similar kinds of steel, because ECAE deformation influence.Originality/value: The results from his work shall be useful in determining conditions for fabrication of nanocrystalline or sub-microcrystalline steel by the ECAE technology.

M. Greger

2009-05-01

275

The Effect of Cooling Rate, and Cool Deformation Through Strain-Induced Transformation, on Microstructural Evolution and Mechanical Properties of Microalloyed Steels  

Science.gov (United States)

In this article, a detailed study was conducted to evaluate the microstructural evolution and mechanical properties of microalloyed steels processed by thermomechanical schedules incorporating cool deformation. Cool deformation was incorporated into a full scale simulation of hot rolling, and the effect of prior austenite conditioning on the cool deformability of microalloyed steels was investigated. As well, the effect of varying cooling rate, from the end of the finishing stage to the cool deformation temperature, 673 K (400 °C), on mechanical properties and microstructural evolution was studied. Transmission electron microscopy (TEM) analysis, in particular for Nb containing steels, was also conducted for the precipitation evaluation. Results show that cool deformation greatly improves the strength of microalloyed steels. Of the several mechanisms identified, such as work hardening, precipitation, grain refinement, and strain-induced transformation (SIT) of retained austenite, SIT was proposed, for the first time in microalloyed steels, to be a significant factor for strengthening due to the deformation in ferrite. Results also show that the effect of precipitation in ferrite for the Nb bearing steels is greatly overshadowed by SIT at room temperature.

Mousavi Anijdan, S. H.; Yue, Steve

2012-04-01

276

Effect of aging and deformation on the microstructure and properties of Fe-Ni-Ti maraging steel  

Science.gov (United States)

The age-hardening behavior of Fe-25.3Ni-1.7 Ti (wt pct) alloy both in undeformed specimens and in specimens cold deformed by 10 or 20 pct prior to aging was studied. The microstructural changes during aging were observed using transmission electron microscopy (TEM) and atom probe analysis and there were related to the mechanical properties as measured by microhardness and shear punch testing. An excellent combination of hardness, strength, and ductility was achieved after only 5 seconds aging at 550°C. We propose that this rapid strengthening is due to a dislocation friction effect arising from the formation of a fine dispersion of Ni-Ti atomic co-clusters during this short aging time. The concomitant effects of a reverse transformation of martensite to austenite during aging and a gradual increase in both size of the clusters and distance between them contributed to a decrease in strength after aging for 15 seconds. This decline proceeded until aging for 300 seconds and was followed by a secondary hardening reaction toward peak hardness (at 10,800 seconds) and subsequent overaging. This secondary hardening was associated with fine-scale precipitation of Ni3Ti and this process was accelerated by deformation prior to aging, leading to a reduction or elimination of hardness decline after the initial cluster hardening.

Shekhter, A.; Aaronson, H. I.; Miller, M. K.; Ringer, S. P.; Pereloma, E. V.

2004-03-01

277

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

International Nuclear Information System (INIS)

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 predomina long-term use. This seems to be predominantly important in benign bronchial collapse

278

The effect of aluminium on mechanical properties and deformation mechanisms of hadfield steel single crystals  

Science.gov (United States)

On single crystals of Hadfield steel (Fe-13Mn-1.3C, Fe-13Mn-2.7Al-1.3C, wt.%) the systematical investigations of deformation mechanisms - slip and twinning, stages of plastic flow, strain hardening coefficient depending on orientation of tensile axis have been carried out by methods of optical and electron microscopy, x-ray analysis. Is has been shown that the combination of low stacking fault energy (?{SF}=0.03J/m^2) with high concentration of carbon atoms in aluminium-free steel results in development of the mechanical twinning at room temperature in all crystal orientations. The new type of twinning with formation of extrinsic stacking fault has been found out in [001] single crystals. Experimentally it has been established that alloying with aluminium leads to increase of stacking fault energy of Hadfield steel and suppresses twinning in all orientations of crystals at preservation of high values of strain-hardening coefficients ?.

Zakharova, E. G.; Kireeva, I. V.; Chumlyakov, Y. I.; Shul'Mina, A. A.; Sehitoglu, H.; Karaman, I.

2004-06-01

279

Magnetorheological and deformation properties of magnetically controlled elastomers with hard magnetic filler  

International Nuclear Information System (INIS)

Viscoelastic and deformational behavior of soft magnetic elastomers with hard magnetic fillers under the influence of a magnetic field is studied by different experimental techniques. The magnetic elastomers used in this work were synthesized on the basis of silicone rubber filled with FeNdB particles and were magnetized in a field of 3 and 15 kOe. We have shown that due to high residual magnetization the materials demonstrate well pronounced non-elastic behavior already in the absence of any external magnetic field. In particular, in contrast to magnetic elastomers based on soft magnetic fillers their elastic modulus is strain-dependent. Under the influence of external magnetic field the storage and loss moduli of magnetic elastomers with hard magnetic filler can both increase and decrease tremendously.

280

Some properties of an infinite family of deformations of the harmonic oscillator  

Science.gov (United States)

In memory of Marcos Moshinsky, who promoted the algebraic study of the harmonic oscillator, some results recently obtained on an infinite family of deformations of such a system are reviewed. This set, which was introduced by Tremblay, Turbiner, and Winternitz, consists in some Hamiltonians Hk on the plane, depending on a positive real parameter k. Two algebraic extensions of Hk are described. The first one, based on the elements of the dihedral group D2k and a Dunkl operator formalism, provides a convenient tool to prove the superintegrability of Hk for odd integer k. The second one, employing two pairs of fermionic operators, leads to a supersymmetric extension of Hk of the same kind as the familiar Freedman and Mende super-Calogero model. Some connection between both extensions is also outlined.

Quesne, Christiane

2010-12-01

281

Bulk crustal properties in NE Tibet and its implication for deformation model  

Science.gov (United States)

The crust beneath the northeastern (NE) Tibetan Plateau records far field effects of collision and convergence occurring between the Indian and Eurasian plates. A better structural understanding of the crust beneath NE Tibet can improve our understanding of Cenozoic deformation resulting from the India-Eurasia collision. Taking advantage of the relatively dense coverage in most areas in NE Tibet except for the Qaidam basin by regional seismic networks of Gansu and Qinghai Provinces, we isolate receiver functions from the teleseismic P wave data recorded from 2007 to 2009 and resolve the spatial distribution of crustal thickness and Vp/Vs ratio beneath NE Tibet from H-K scanning. Our results can be summarized as: (1) NE Tibet is characterized by ~ 60-km-thick crust beneath the Nan Shan, Qilian Shan thrust belts and the Anyemaqen Shan, and 45-50 km-thick crust beneath the Tarim basin, the Alashan depression and the Ordos basin; the crust thins gradually from west to east in addition to the previously observed pronounced thinning from south to north; (2) the crust of NE Tibet exhibits a relatively lower Vp/Vs ratio of 1.72 than the north China block and a decrease in average crustal Vp/Vs ratio with increasing crustal thickness; and (3) the crustal thicknesses are less than the values predicted by the simple isostatic model of throughout Tibetan plateau in where the elevation is larger than 3.0 km. Our observations can be explained by the hypothesis that deformation occurring in NE Tibet is predominated by upper-crustal thickening or lower-crust extrusion.

Tian, Xiaobo

2014-05-01

282

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

CERN Document Server

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.

Peru, S

2008-01-01

283

A 3D-RBS study of irradiation-induced deformation and masking properties of ordered colloidal nanoparticulate masks  

International Nuclear Information System (INIS)

The 500 keV Xe2+ irradiation-induced anisotropic deformation of ordered colloidal silica nanoparticulate masks is followed using 2 MeV 4He+ Rutherford Backscattering Spectrometry (RBS) with different measurement geometries and the improved data analysis capabilities of the RBS-MAST spectrum simulation code. The three-dimensional (3D) geometrical transformation from spherical to oblate ellipsoidal and polygonal shape and the decrease of the mask's hole size is described. The masking properties of the silica monolayer and the depth distribution of Xe in the underlying Si substrate vs. the irradiated Xe2+ fluence are discussed. Field Emission Scanning Electron Microscopy (FESEM) is applied as complementary characterization tool. Our results give contribution to clarify the impact of ion-nanoparticle interactions on the potentials and limits of nanosphere lithography. We also show the capability of the conventional RBS technique to characterize laterally ordered submicron-sized three-dimensional structures.

284

Influence of cold deformation on stability of structure and high temperature properties of 15Kh1M1F steel  

International Nuclear Information System (INIS)

Stability of structure and properties in 15Kh1M1F heat resistant cold worked steel was investigated. Reduction in area was equal to 11-13%. Heat resistance tests were conducted at 570 deg C. Structural and properta yy stability was evaluated through ield strength/ultimate strength ratio and a yield strength/tangent o.f slope angle of long-term strength curve ratio. It is found that cold plastic deformation changes the picture of structural stability compared to an initial state. Under long- term high temperature loading of 15Kh1M1F steel a ferrite-carbide structure is stable for a nondeformed state and an upper bainite structure is stable for a cold worked state

285

Effect of deformation temperature on mechanical properties of ultrafine grained Al–Mg alloys processed by rolling  

International Nuclear Information System (INIS)

Highlights: ? Mechanical properties and microstructural evolution of cryorolled + warm rolled (WR) Al 5083 alloy were investigated. ? WR samples showed a significant improvement in tensile strength and ductility (6.8%) than CR samples. ? WR sample is thermally stable up to 250 °C. ? YS and UTS of WR sample annealed at 250 °C are 270 MPa and 330 MPa, respectively, and elongation to failure is 13%. - Abstract: Aluminum–Magnesium (Al 5083) alloy was subjected to cryorolling (CR) and cryorolling followed by warm rolling (WR) in order to investigate the changes in mechanical behavior and microstructure evolution in the present work. Al alloy specimens were first cryorolled up to 50% thickness reduction followed with warm rolling at 100 °C, 145 °C, 175 °C and 200 °C till to achieve total 90% thickness reduction. The final microstructure of all conditions were analyzed and compared through transmission electron microscopy (TEM), Electron back scattered diffraction (EBSD), and X-ray diffraction (XRD) techniques to investigate the effect of WR deformation temperatures on mechanical properties. The mechanical behavior of the processed samples were evaluated through hardness and tensile tests performed at room temperature. An increase in yield strength (522 MPa), ultimate tensile strength (539 MPa) and ductility (6.8%) was observed in WR specimens at 175 °C, hardness also increases to (146 HV) as compared to CR samples. These samples were annealed in temperature range from 150 °C to 300 °C to investigate their thermal stability. The CR samples exhibited severely deformed structure with high dislocation density network while cryorolled followed by warm rolled (WR) samples has shown formation of ultrafine grains associated with dynamic recovery. At elevated temperature of 200 °C, WR samples showed decrease in strength accompanied with increase in elongation due to dominant dynamic recovery effect led to reduction in dislocation density

286

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

287

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

Science.gov (United States)

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.

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

2013-07-01

288

Radiation and helium effects on microstructures, nano-indentation properties and deformation behavior in ferrous alloys  

International Nuclear Information System (INIS)

Accelerated ion irradiation, especially 'dual-beam' irradiation, is a useful technique for experimental exploration of irradiation effects and validation of irradiation effect models, because of the unique controllability in irradiation conditions including the helium production rate. In this work, the effects of irradiation and helium implantation on microstructural evolution, hardness and plastic deformation behavior in Fe-15Cr-20Ni model austenitic ternary alloy and Fe-8 ? 9Cr-2W reduced-activation martensitic steels were studied through combined applications of ion irradiation, nano-indentation, focused ion-beam microprocessing and transmission electron microscopy. Systematic data on irradiation hardening are presented for broad irradiation conditions. Influences of helium implantation on irradiation-induced microstructural and nano-indentation hardness changes were not detected in the Fe-8 ? 9Cr-2W steels, while they were significant in the Fe-15Cr-20Ni alloy. The interaction behavior of dislocation loops with moving dislocations and the strength of the loops as obstacles to dislocation motion are also discussed for these two material classes based on the hardness, and the irradiated and indented microstructures

289

Mechanical and corrosion properties of aluminium alloy EN AW 6082 after severe plastic deformation (SPD)  

OpenAIRE

The aim had been to study changes in the properties of aluminium alloy AlSiMgMn. Influence of SPD of the mechanical properties had increased (Rm by 86 MPa, Ro0,2 by 175 MPa, while A had decreased to 20 %). The corrosion potentials had been evaluated in the environment of H2O and in SARS. After SPD was observed in the environment of H2O, that resistance had increased by -218 mV and after exposure up to 1 000 min there was a slight deterioration of resistance in...

Lackova?, P.; Burs?a?k, M.; Kvac?kaj, T.; Halama, M.

2015-01-01

290

Influence of prelimiraty deformation and heat treatment on the technological plasticity, structure and properties of ZhS6-KP alloy under pressing  

International Nuclear Information System (INIS)

Questions of raising - before pressure moulding - the technological plasticity of ingots of the alloy ZhS6-KP by preliminary deformation (pre-moulding and annealing) are considered. The optimum sequence of annealing and pre-moulding for obtaining good plastic properties is established. (author)

291

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

Directory of Open Access Journals (Sweden)

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.

W. Ozgowicz

2008-07-01

292

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

International Nuclear Information System (INIS)

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.

293

Higher-multipole deformations and compactness of hot fusion reactions  

International Nuclear Information System (INIS)

The effect of adding the higher-multipole deformations ?6 and ?8, and the octupole deformation ?3 (in addition to quadrupole and hexadecapole deformations ?2 and ?4), on the distribution of barriers in orientation degrees of freedom is studied for a ''compact'' configuration of spherical-plus-deformed or deformed-plus-deformed nuclei in hot fusion reactions. Though ?3 is known to be nonzero for only a few nuclei, its role toward compactness of hot fusion reactions is found to be as important as that of ?4. With ?3 included, depending on its sign and magnitude, the belly-to-belly compact, bbc (or equatorial compact, ec), configuration due to ?4 changes to not-belly-to-belly compact, nbbc (or not-equatorial compact, nec), and vice versa. Similarly, ?6 is found to be as important as ?3 and/or ?4 for spherical-plus-deformed nuclei, but is rather insignificant for collisions involving deformed-plus-deformed nuclei. On the other hand, the addition of ?8 is shown to be insignificant also for spherical-plus-deformed nuclei

294

Annealing behaviour and mechanical properties of severely deformed interstitial free steel  

International Nuclear Information System (INIS)

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 ?-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 anical properties depend on both, grain size and area fraction of HAGBs.

295

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

International Nuclear Information System (INIS)

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 ? Ti, and no ? 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.

296

A deformable shell model study of the properties of CsCl  

International Nuclear Information System (INIS)

The deformable shell model has been put to a stringent test by calculating the transition temperature for transition of CsCl crystal from the CsCl-to the NaCl-structure. Because of the very small heat of transition this calculation is a very sensitive test of the model. Einstein approximation is used for estimating the thermal part of free energy. The transition temperature has been obtained by equating the Helmholtz free energy for the two phases at transition since the volume change accompanying transition is very small and the transition takes place at atmospheric pressure. The static lattice energy expression used for computing the free energy is obtained from the effective interaction including the many body interaction. The equation of state has also been calculated using the relation -P = (deltaF/deltaV)sub(T), as a further test of the validity of the model. Finally, the same model has been used to improve upon the lattice dynamical calculation by incorporating the effect of the polarizability of Cs+ ion on the phonon dispersion curves. The nearest neighbour distance at room temperature and at transition point in the CsCl-phase comes out within 0.1% of the experimental values. These have been determined for any particular temperature by minimizing the Helmholtz free energy at that temperature. The transition temperature has been reproduced almost exactly and in the calculation of the equation of state, the agreement with experiment is within 8% even reement with experiment is within 8% even at the highest compression. It has also been found that the inclusion of the positive ion polarizability improves the phonon dispersion curves of Ghosh and Basu remarkably with relatively a few number of parameters. The only remaining notable discrepancy is reported at the zone boundary along (110) direction for both the L.O. and T.O. branches and those too are found to be 5.2% and 4.6% respectively. (K.B.)

297

Deformation of Lambda hypernuclei  

OpenAIRE

We study the deformation property of $\\Lambda$ hypernuclei using the relativistic mean field (RMF) method. We find that $^{29}_{\\Lambda}$Si and $^{13}_{\\Lambda}$C hypernuclei have spherical shape as a consequence of the additional $\\Lambda$ particle, whereas the corresponding core nuclei, $^{28}$Si and $^{12}$C, are oblately deformed. Most of other hypernuclei have a similar deformation parameter to the core nucleus, in accordance with the previous study with the non-relativ...

Win, Myaing Thi; Hagino, K.

2008-01-01

298

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2008-05-16

299

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

Science.gov (United States)

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.

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

2010-12-01

300

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

International Nuclear Information System (INIS)

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)

301

Mechanical and corrosion properties of aluminium alloy EN AW 6082 after severe plastic deformation (SPD  

Directory of Open Access Journals (Sweden)

Full Text Available The aim had been to study changes in the properties of aluminium alloy AlSiMgMn. Influence of SPD of the mechanical properties had increased (Rm by 86 MPa, Ro0,2 by 175 MPa, while A had decreased to 20 %. The corrosion potentials had been evaluated in the environment of H2O and in SARS. After SPD was observed in the environment of H2O, that resistance had increased by -218 mV and after exposure up to 1 000 min there was a slight deterioration of resistance in SARS. On the surface specimens after SPD were observed higher quantities of corrosion products. After SPD was observed fatigue characteristics in torsional stress in the oblique branches Wohler curves showed favourable characteristics of about 35 %.

P. Lacková

2015-01-01

302

Joint Probability Distribution Function for the Electric Microfield and its Ion-Octupole Inhomogeneity Tensor  

International Nuclear Information System (INIS)

From experiments, see e.g. [W. Wiese, D. Kelleher, and D. Paquette, Phys. Rev. A 6, 1132 (1972); V. Helbig and K. Nich, J. Phys. B 14, 3573 (1981).; J. Halenka, Z. Phys. D 16, 1 (1990); . Djurovic, D. Nikolic, I. Savic, S. Sorge, and A.V. Demura, Phys. Rev. E 71, 036407 (2005)], results that the hydrogen lines formed in plasma with Ne ? 1016 cm-3 are asymmetrical. The inhomogeneity of ionic micro field and the higher order corrections (quadratic and next ones) in perturbation theory are the reason for such asymmetry. So far, the ion-emitter quadrupole interaction and the quadratic Stark effect have been included in calculations. The recent work shows that a significant discrepancy between calculations and measurements occurs in the wings of H-beta line in plasmas with cm-3. It should be stressed here that e.g. for the energy operator the correction raised by the quadratic Stark effect is proportional to (where is the emitter-perturber distance) similarly as the correction caused by the emitter-perturber octupole interaction and the quadratic correction from emitter-perturber quadrupole interaction. Thus, it is obvious that a model of the profile calculation is consistent one if all the aforementioned corrections are simultaneously included. Such calculations are planned in the future paper. A statistics of the octupole inhomogeneity tensor in a plasma is necessarily needed in the first step of such calculations. For the first time the distribution functions of the octupole inhomogeneity have been calculated in this paper using the Mayer-Mayer cluster expansion method similarly as for the quadrupole function in the paper [J. Halenka, Z. Phys. D 16, 1 (1990)]. The quantity is the reduced scale of the micro field strength, where is the Holtsmark normal field and is the mean distance defined by the relationship, that is approximately equal to the mean ion-ion distance; whereas is the screening parameter, where is the electronic Debye radius. (author)

303

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

International Nuclear Information System (INIS)

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

304

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

OpenAIRE

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...

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

2004-01-01

305

Annealing behaviour and mechanical properties of severely deformed interstitial free steel  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Microstructure and micro-texture evolution indicates continuous recrystallisation. Black-Right-Pointing-Pointer HAGBs decrease from {approx}80 to {approx}40% due to texture clustering and orientation pinning. Black-Right-Pointing-Pointer Characterisation of correlation between tensile and shear punch tests. Black-Right-Pointing-Pointer 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 {alpha}-fibre rolling texture and a decrease in area fraction of high angle grain boundaries from {approx}80% to {approx}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.

Gazder, Azdiar A. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia); Hazra, Sujoy S., E-mail: sujoy.hazra@gmail.com [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia); Pereloma, Elena V. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia)

2011-12-15

306

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

CERN Document Server

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.

Leung, Kent

2008-01-01

307

Effect of the lattice octupole fields on the synchro-betatron mode coupling instability  

Energy Technology Data Exchange (ETDEWEB)

Within the framework of a simplifying model and in the first approximation of the perturbation theory we discuss the effect of the Landau damping on the synchro-betatron mode coupling instability of a single bunch in a storage ring. We assume that the required by Landau damping frequency spreads of the betatron and of the synchro-betatron modes are provided by the octupole nonlinearity of the ring lattice focusing. We also assume that the wakefields of the bunch decay substantially during the revolution period of particles along the closed orbit. For this reason, the memory of the bunch wakefields are ignored in this paper.

Pestrikov, D.V., E-mail: pestrikov@inp.nsk.su [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

2014-02-21

308

Effect of the lattice octupole fields on the synchro-betatron mode coupling instability  

International Nuclear Information System (INIS)

Within the framework of a simplifying model and in the first approximation of the perturbation theory we discuss the effect of the Landau damping on the synchro-betatron mode coupling instability of a single bunch in a storage ring. We assume that the required by Landau damping frequency spreads of the betatron and of the synchro-betatron modes are provided by the octupole nonlinearity of the ring lattice focusing. We also assume that the wakefields of the bunch decay substantially during the revolution period of particles along the closed orbit. For this reason, the memory of the bunch wakefields are ignored in this paper

309

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

International Nuclear Information System (INIS)

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)

310

High-energy component of giant octupole resonance in medium and heavy mass nuclei  

International Nuclear Information System (INIS)

Inelastic scattering of 3He particles at 110--140 MeV from /sup 90,92/Zr, /sup 116,118,120/Sn, 144Sm, and 208Pb nuclei exhibits the presence of a new giant resonance at E/sub x/approx.118A/sup -1/3/ MeV with a width of about 7 MeV. The angular distributions are consistent with those for L=3 transfer and octupole energy-weighted sum-rule fractions of 47--95% are exhausted for the resonance

311

Interrelation between the isoscalar octupole phonon and the proton-neutron mixed-symmetry quadrupole phonon in near spherical nuclei  

OpenAIRE

The interrelation between the octupole phonon and the low-lying proton-neutron mixed-symmetry quadrupole phonon 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+ 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...

Smirnova, Nadya A.; Pietralla, Norbert; Mizusaki, Takahiro; Isacker, Piet

2000-01-01

312

Fracture and deformation properties of Ni-Fe superalloy in cryogenic high magnetic field environments  

Science.gov (United States)

The present paper includes experimental and analytical data on the fracture properties of a nickel-iron superalloy, a ferromagnetic austenite, at 4 K in magnetic fields of 0 and 6 T. The tensile, notch tensile and small punch tests are employed. A finite element analysis is also performed to convert the experimentally measured load-displacement data into useful engineering information. To interpret the results we review the available theory of the influence of magnetic field on the stress intensity factor for a crack in ferromagnetic materials.

Yamaguchi, Yoko; Horiguchi, Katsumi; Shindo, Yasuhide; Sekiya, Daisuke; Kumagai, Susumu

2003-08-01

313

Structure and mechanical properties of an Ni3Al single crystal upon high-temperature deformation  

Science.gov (United States)

Structure and strength properties of single-crystal samples of Ni3Al have been studied in the as-grown and homogenized state during tensile tests in the temperature range of 1150-1250°C. At the strain rate of 1.32 mm/min (2 × 10-5 m/s), the samples are in the state of superplasticity. The basic mechanism of relaxation is dynamic recovery; in some regions of the sample, recrystallized grains are formed. At 1250°C, coarse twins are observed in the zone of fracture, which indicates the "switching on" of additional slip systems necessary to guarantee the relaxation process.

Stepanova, N. N.; Davydov, D. I.; Rodionov, D. P.; Philippov, Yu. I.; Akshentsev, Yu. N.; Vinogradova, N. I.; Kazantseva, N. V.

2011-04-01

314

Mobility of vacancies under deformation and their effect on the elastic properties of graphene  

International Nuclear Information System (INIS)

The effect of isolated vacancies on the elastic properties of a graphene sheet has been investigated by the ab initio density functional method. An almost inverse linear dependence of the Young’s modulus on the concentration of vacancies has been revealed. The height of potential barriers for the motion of vacancies in various directions has been calculated as a function of various independent applied strains. The velocity of vacancies at various temperatures has been calculated as a function of applied strains using the transition state theory.

315

Microstructure, properties, and failure characteristics of medium-carbon steel subjected to severe plastic deformation  

Science.gov (United States)

The paper deals with two-stage processing of medium-carbon steel 45 (0.45 % C; 0.27 % Si; 0.65 % Mn) via quenching and high pressure torsion. Such processing combination allowed producing a nanocomposite microstructure with a ferrite matrix and high-dispersed carbides. The ultimate tensile strength of the nanostructured steel is over 2500 MPa. The processing effect on the structure, mechanical properties and failure mechanisms of steel 45 samples is studied. The peculiarities of static fractures in the samples after HPT are demonstrated in comparison with those after quenching.

Karavaeva, Marina V.; Kiseleva, Svetlana K.; Abramova, Marina M.; Ganeev, Artur V.; Valiev, Ruslan Z.

2014-08-01

316

Structure and mechanical properties of the 03Kh14GNF steel after deformation and annealing  

Science.gov (United States)

It has been shown that the annealing of cold-worked 03Kh14GNF steel is accompanied by several strengthening and softening processes that take place in different temperature intervals. Therefore, the temperature dependence of its hardness has a complicated form; i.e., it contains several maxima and minima. The following processes should be noted: recovery and recrystallization of ? ferrite, precipitation of M 2(CN) carbonitrides and M 23C6 carbides from the ? martensite, their dissolution in the ? phase, the formation of austenite with different stability, polygonization of the ? martensite, etc. Tempering for 30 h can produce the level of mechanical properties required according to technical specifications for two processing regimes. These regimes are the annealing at 680°C and at 600°C, but in the second case the high plasticity is probably caused by the formation of a highly stable austenite that is retained down to room temperature. However, the degree of plasticity of this ? phase at room and lower temperatures is unknown. After annealing at 660°C, the steel does not achieve the level of ultimate strength of 480 N/mm2, which is required by the technical specifications. However, since the relative elongation of 35% exceeds the required magnitude, the required level of mechanical properties can apparently be produced by a decrease in the duration of annealing to 20-25 h.

Shaburov, D. V.; Valitov, V. G.; Mirzaev, D. A.; Yakovleva, I. L.; Kirpichnikov, M. S.; Vetoshkina, T. Yu.

2009-04-01

317

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

Directory of Open Access Journals (Sweden)

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.

J. Zrnik

2009-07-01

318

Deformation and fracture properties of neutron-irradiated recrystallized zircaloy-2 cladding under uniaxial tension  

International Nuclear Information System (INIS)

Sufficient evaluation of the changes in mechanical properties, such as elastic, plastic, and failure properties, due to neutron irradiation in service is required to precisely predict fuel performance. This paper presents the results of the uniaxial tensile tests performed for recrystallized (850 K, 2.5 h) Zircaloy-2 claddings irradiated in commercial BWRs to fluences of 5 x 1023 to 4 x 1025 nm2 (E > 1 MeV). The material constants of irradiated Zircaloy-2 were obtained precisely, using a high temperature elongation detector in a hot-cell and computer analyses of digital stress-strain data. The tensile tests were carried out at 298 to 673 K at strain rates of 0.05 to 5%min, using tubular specimens cut to 135 mm lengths from the claddings. From these tests, Young's modulus, strain hardening exponent, strain rate sensitivity, and fracture behavior were obtained and evaluated. Young's modulus of specimens irradiated to 1024 nm2 is nearly equal to that of unirradiated ones, but irradiation to 1025 nm2 shows values 7% higher than for unirradiated ones. The irradiation-induced increments in yield stress are rapid 1 x 1024 nm2, then slow down above this fluence becoming proportional to (phit)/sup 0.1/ for fluences of 1 x 1024 to 4 x 1025 nm2, where phit is fluence

319

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  

Energy Technology Data Exchange (ETDEWEB)

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.)

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

2014-04-15

320

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

Directory of Open Access Journals (Sweden)

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.

Jab?o?ska M.B.

2014-10-01

321

Effects of Deformation Processing on the Mechanical Properties of Aluminum Alloy 6063  

Science.gov (United States)

Aluminum alloy 6063 was processed by upset forging and cold rolling at ambient temperature. The tensile, ductile, and hardness (HRN) properties of the samples were studied. Upset forging is determined from the processing of this alloy to obtain maximum ultimate tensile strength (UTS) and HRN. At room temperature, the UTS and HRN increase as the range of reduction from processing increases from 0 to 50 pct. However, the ductility decreases correspondingly, which is indicative of a low strain-hardening exponent. The gaseous pores in the as-cast structure spread when forged, while the rolling had no effect on this casting defect. The pore elongation and thinning promoted superior strength, HRN, and ductility in the forged sample, as compared to the cold-rolled sample.

Balogun, Sanmbo A.; Esezobor, David E.; Adeosun, Samson O.

2007-07-01

322

High-accuracy optical clock based on the octupole transition in 171Yb+  

CERN Document Server

We experimentally investigate an optical frequency standard based on the 467 nm (642 THz) electric-octupole reference transition 2S1/2(F=0) -> F7/2(F=3) in a single trapped 171Yb+ ion. The extraordinary features of this transition result from the long natural lifetime and from the 4f136s2 configuration of the upper state. The electric quadrupole moment of the 2F7/2 state is measured as -0.041(5) e(a0)^2, where e is the elementary charge and a0 the Bohr radius. We also obtain information on the differential scalar and tensorial components of the static polarizability and of the probe light induced ac Stark shift of the octupole transition. With a real-time extrapolation scheme that eliminates this shift, the unperturbed transition frequency is realized with a fractional uncertainty of 7.1x10^(-17). The frequency is measured as 642 121 496 772 645.15(52) Hz with the uncertainty essentially determined by the employed caesium fountain reference.

Huntemann, N; Lipphardt, B; Weyers, S; Tamm, Chr; Peik, E

2011-01-01

323

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

Science.gov (United States)

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 92Zr and 94Mo. Purpose: The heaviest stable N =52 isotone 96Ru was investigated to study the evolution of octupole and hexadecapole MSS with increasing proton number. Methods: Two inelastic proton-scattering experiments on 96Ru were performed to extract branching ratios, multipole mixing ratios, and level lifetimes. From the combined data, absolute transition strengths were calculated. Results: Strong M 1 transitions between the lowest-lying 3- and 4+ states were observed, providing evidence for a one-phonon mixed-symmetry character of the 32(-) and 42+ states. Conclusions: s d g -IBM-2 calculations were performed for 96Ru. The results are in excellent agreement with the experimental data, pointing out a one-phonon hexadecapole mixed-symmetry character of the 42+ state. The matrix element is found to scale with the matrix element.

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

2014-11-01

324

Persistence of octupole correlations in sup 2 sup 3 sup 1 Ra  

CERN Document Server

The structure of sup 2 sup 3 sup 1 Ra, the heaviest odd Ra nucleus currently accessible for detailed spectroscopic investigation, has been studied in the beta sup - decay of sup 2 sup 3 sup 1 Fr. The main purpose has been to verify whether fast B(E1) rates and significant octupole correlations recently established in sup 2 sup 2 sup 9 Ra persist in sup 2 sup 3 sup 1 Ra. The excited states in sup 2 sup 3 sup 1 Ra have been determined for the first time. Spins and parities have been deduced from conversion electron measurements, while level half-lives in the ps and ns ranges have been measured with the Advanced Time Delayed beta gamma gamma(t) method. The moderately fast B(E1) rates found for transitions connecting the lowest-lying K suppi=5/2 sup+- and K suppi=1/2 sup+- bands, reveal the persistence of octupole collective effects in sup 2 sup 3 sup 1 Ra, although the B(E1) rates are lower than in sup 2 sup 2 sup 9 Ra. These findings reinforce the differences in the B(E1) systematics between isotonic Ra and Th ...

Fraile-Prieto, L M; Mach, H; Boutami, R; Aas, A J; Fogelberg, B; García-Raffi, L M; Grant, I S; Gulda, K; Hageboe, E; Kurcewicz, W; Kvasil, J; López, M J; Løvhøiden, G; Martínez, T; Rubio, B; Taín, J L; Tengblad, O

2001-01-01

325

High-Accuracy Optical Clock Based on the Octupole Transition in Yb+171  

Science.gov (United States)

We experimentally investigate an optical frequency standard based on the 467 nm (642 THz) electric-octupole reference transition S1/22(F=0)?F7/22(F=3) in a single trapped Yb+171 ion. The extraordinary features of this transition result from the long natural lifetime and from the 4f136s2 configuration of the upper state. The electric-quadrupole moment of the F7/22 state is measured as -0.041(5)ea02, where e is the elementary charge and a0 the Bohr radius. We also obtain information on the differential scalar and tensorial components of the static polarizability and of the probe-light-induced ac Stark shift of the octupole transition. With a real-time extrapolation scheme that eliminates this shift, the unperturbed transition frequency is realized with a fractional uncertainty of 7.1×10-17. The frequency is measured as 642 121 496 772 645.15(52) Hz.

Huntemann, N.; Okhapkin, M.; Lipphardt, B.; Weyers, S.; Tamm, Chr.; Peik, E.

2012-03-01

326

Confined crystallization, crystalline phase deformation and their effects on the properties of crystalline polymers  

Science.gov (United States)

With the recent advances in processing and catalyst technology, novel morphologies have been created in crystalline polymers and they are expected to substantially impact the properties. To reveal the structure-property relationships of some of these novel polymeric systems becomes the primary focus of this work. In the first part, using an innovative layer-multiplying coextrusion process to obtain assemblies with thousands of polymer nanolayers, dominating "in-plane" lamellar crystals were created when the confined poly(ethylene oxide) (PEO) layers were made progressively thinner. When the thickness was confined to 25 nanometers, the PEO crystallized as single, high-aspect-ratio lamellae that resembled single crystals. This crystallization habit imparted more than two orders of magnitude reduction in the gas permeability. The dramatic decrease in gas permeability was attributed to the reduced diffusion coefficient, because of the increase in gas diffusion path length through the in-plane lamellae. The temperature dependence of lamellar orientation and the crystallization kinetics in the confined nanolayers were also investigated. The novel olefinic block copolymer (OBC) studied in the second part consisted of long crystallizable sequences with low comonomer content alternating with rubbery amorphous blocks with high comonomer content. The crystallizable blocks formed lamellae that organized into space-filling spherulites even when the fraction of crystallizable block was so low that the crystallinity was only 7%. These unusual spherulites were highly elastic and recovered from strains as high as 300%. These "elastic spherulites" imparted higher strain recovery and temperature resistance than the conventional random copolymers that depend on isolated, fringed micellar-like crystals to provide the junctions for the elastomeric network. In the third part, positron annihilation lifetime spectroscopy (PALS) was used to obtain the temperature dependence of the free volume hole size in propylene/ethylene copolymers over a range in comonomer content. Above the glass transition temperature (Tg), the reduced free volume hole size and the densification of the amorphous phase were attributed to constraint imposed on rubbery amorphous chain segments by attached chain segments in crystals. However constant free volume fraction was found at Tg, across the crystallinity range of the copolymers, in agreement with the iso-free volume concept of glass transition.

Wang, Haopeng

327

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

Energy Technology Data Exchange (ETDEWEB)

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.

Pichaud, B.; Regula, G. [Aix-Marseille Université, CNRS, IM2NP, UMR 7334, 13397, Marseille, France and Université de Toulon, CNRS, IM2NP, UMR 7334, 83957, La Garde (France); Yakimov, E. B. [Institute of Microelectronics Technology RAS, 142432, Chernogolovka (Russian Federation)

2014-02-21

328

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

Science.gov (United States)

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.

Pichaud, B.; Regula, G.; Yakimov, E. B.

2014-02-01

329

Mechanical properties and microstructure of 6061 aluminum alloy severely deformed by ARB process and subsequently aged at low temperatures  

Science.gov (United States)

In order to clarify the aging behavior in ultrafine grained (UFG) Al alloys, a commercial Al-Mg-Si alloy was severely deformed by accumulative roll-bonding (ARB) process and subsequently aged at 100°C or 170°C. The age-hardening behavior and microstructure change during aging were investigated. At 170 °C, age-hardening was observed in solution treated (ST) specimens, but solution-treated and ARB-processed specimens were not hardened by aging. On the other hand, the hardness of the both ST specimen and ARB-processed specimen increased by aging at 100°C. From TEM observation, it was found that the ARB- processed specimen had an ultrafine lamellar boundary structure and the structure was kept during aging at 170°C and 100°C. In the ST specimen aged at 170°C, fine precipitates were observed within coarse grains. In the specimen ARB-processed and subsequently aged at 170°C, coarser precipitates were observed within ultrafine grains and on grain boundaries. It was considered that the reason why the hardness of the specimens ARB-processed and subsequently aged did not increase was coarsening of precipitates. In the specimens aged at 100°C, obvious precipitates were not observed, but clusters Mg and Si seemed to form during the aging, leading to the increase in the hardness of the specimen. From the results, it was suggested that aging at low temperatures could improve mechanical properties of Al alloys through combining grain refinement and precipitation hardening.

Terada, Daisuke; Kaneda, Yoma; Horita, Zenji; Matsuda, Kenji; Hirosawa, Shoichi; Tsuji, Nobuhiro

2014-08-01

330

Gender features of rheological properties of blood (plasma viscosity, aggregation and deformation of erythrocytes in patients with chronic generalized periodontitis  

Directory of Open Access Journals (Sweden)

Full Text Available The goal is to study gender features of rheological properties of blood in patients with chronic generalized periodontitis (CGP from mild to moderate severity. Material and Methods. 80 patients (43.8% male with CGP aged 42±5 years have been studied. 41 patients (43.9% male experienced mild severity of CGP, and 39 patients (43.6% male experienced moderate severity. 40 healthy adults (50% male, aged 31±7 years, have been included into the study. Plasma viscosity on shear rate values 300 sec1 to 5 sec1, and rheological features of erythrocytes (aggregation and deformation have been evaluated. Results. In healthy women and women with mild severity of CGP, plasma viscosity was lower than in the similar group of men. The rheological features of erythrocytes have not gender differences among healthy adults and patients with mild CGP. Increased severity of CGP has been associated with increased plasma viscosity and rheological features of erythrocytes, particularly in men. Conclusion. Plasma viscosity differs in men and women (childbearing age (healthy subjects and patients with CGP. In women, severity of pathological changes of plasma viscosity and rheological features of erythrocytes have been determined to be lower than in men.

Kazantsev A.V.

2014-03-01

331

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

International Nuclear Information System (INIS)

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.)

332

Influence of deformation on the structure and mechanical and corrosion properties of high-nitrogen austenitic 07Kh16AG13M3 steel  

Science.gov (United States)

The correlation has been studied between the structure of a high-nitrogen austenitic Cr-Mn-N steel formed in the process of combined hardening treatment, including cold plastic deformation (CPD), and its mechanical and corrosion properties. The structure and properties of commercial high-nitrogen (0.8% N) 07Kh16AG13M3 steel is analyzed after rolling by CPD and aging at 500 and 800°C. It is shown that CPD of the steel occurs by dislocation slip and deformation twinning. Deformation twinning and also high resistance of austenite to martensitic transformations at true strains of 0.2 and 0.4 determine the high plasticity of the steel. The contribution of the structure imperfection parameters to the broadening of the austenite lines during CPD is estimated by X-ray diffraction. The main hardening factor is stated to be lattice microdistortions. Transmission electron microscopy study shows that heating of the deformed steel to 500°C leads to the formation of the intermediate CrN phase by a homogeneous mechanism, and the intermtallic ? phase forms along the austenite grain boundaries in the case of heating at 800°C. After hardening by all investigated technological schemes, exception for aging at 800°C, the steel does not undergo pitting corrosion and is slightly prone to a stress corrosion cracking during static bending tests, while aging at 800°C causes pitting corrosion at a pitting formation potential E pf = -0.25 V.

Berezovskaya, V. V.; Khadyev, M. S.; Merkushkin, E. A.; Sokolovskaya, Yu. A.

2013-11-01

333

Microstructure and micro-mechanical properties of Y-TZP and Y-TZP/Al2O3 composite after superplastic deformation  

International Nuclear Information System (INIS)

The microstructure and micro-mechanical properties of superplastically deformed Y-TZP ceramics and Y-TZP/Al2O3 composites were investigated. The grain growth on average of the pure Y-TZP ceramics during deformation at the temperature 100 C below the sintering temperature was very limited, while extensive growth of Y-TZP grains in Y-TZP/alumina composites were found under the same condition. The segregation of Y3+ in single phase Y-TZP and the glass phase present at triple points in the composites was believed to be responsible for the different grain growth behavior. The change of mechanical properties of the materials were found to mainly relate to the microstructural change of the materials during deformation. In the case of single phase Y-TZP ceramics, both Vicker's hardness and indentation toughness do not apparently change by deformation, but the indentation toughness of the Y-TZP/alumina composites decreased noticeably due to the extensive grain growth of Y-TZP and thereafter the occurrence of monoclinic zirconia phase

334

Comparison studies on the percolation thresholds of binary mixture tablets containing excipients of plastic/brittle and plastic/plastic deformation properties.  

Science.gov (United States)

Percolation theory has been used with great interest in understanding the design and characterization of dosage forms. In this study, work has been carried out to investigate the behavior of binary mixture tablets containing excipients of similar and different deformation properties. The binary mixture tablets were prepared by direct compression using lactose, polyvinyl chloride (PVC), Eudragit RS 100, and microcrystalline cellulose (MCC). The application of percolation theory on the relationships between compactibility, Pmax, or compression susceptibility (compressibility), gamma, and mixture compositions reveals the presence of percolation thresholds even for mixtures of similar deformation properties. The results showed that all mixture compositions exhibited at least one discreet change in the slope, which was referred to as the percolation threshold. The PVC/Eudragit RS100 mixture compositions showed significant percolation threshold at 80% (w/w) PVC loading. Two percolation thresholds were observed from a series of binary mixtures containing similar plastic deformation materials (PVC/MCC). The percolation thresholds were determined at 20% (w/w) and 80% (w/w) PVC loading. These are areas where one of the components percolates throughout the system and the properties of the tablets are expected to experience a sudden change. Experimental results, however, showed that total disruption of the tablet physical properties at the specified percolation thresholds can be observed for PVC/lactose mixtures at 20-30% (w/w) loading while only minor changes in the tablets' strength for PVC/MCC or PVC/Eudragit RS 100 mixtures were observed. PMID:15554218

Amin, Mohd C I; Fell, John T

2004-01-01

335

Multi-dimensional potential energy surfaces and non-axial octupole correlations in actinide and transfermium nuclei from relativistic mean field models  

Science.gov (United States)

We have developed multi-dimensional constrained covariant density functional theories (MDC-CDFT) for finite nuclei in which the shape degrees of freedom ??? with even ?, e.g., ?20, ?22, ?30, ?32, ?40, etc., can be described simultaneously. The functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the non-linear or density-dependent couplings. For the pp channel, either the BCS approach or the Bogoliubov transformation is implemented. The MDC-CDFTs with the BCS approach for the pairing (in the following labelled as MDC-RMF models with RMF standing for "relativistic mean field") have been applied to investigate multi-dimensional potential energy surfaces and the non-axial octupole Y32-correlations in N = 150 isotones. In this contribution we present briefly the formalism of MDC-RMF models and some results from these models. The potential energy surfaces with and without triaxial deformations are compared and it is found that the triaxiality plays an important role upon the second fission barriers of actinide nuclei. In the study of Y32-correlations in N = 150 isotones, it is found that, for 248Cf and 260Fm, ?32 > 0.03 and the energy is lowered by the ?32 distortion by more than 300 keV; while for 246Cm and 252No, the pocket with respect to ?32 is quite shallow.

Lu, Bing-Nan; Zhao, Jie; Zhao, En-Guang; Zhou, Shan-Gui

2014-03-01

336

Measurement of reduced electric octupole transition probabilities B(E3;O1+ ? 31-), for 118,120,122Sn  

International Nuclear Information System (INIS)

Values of reduced electric octupole transition probabilities B(E3;O1+ ? 31-) for the nuclides 118,120,122Sn have been determined using Coulomb excitation with 12C projectiles. The results are in good agreement with shell-model calculations made without introducing effective charges but involving core excitations. Values for B(E2;O1+ ? 21+) are also presented

337

One-phonon octupole vibrational states in 211At, 212Rn, 213Fr and 214Ra with N = 126  

International Nuclear Information System (INIS)

Excited high spin states in 211At, 212Rn, 213Fr and 214Ra with N = 126 are reorganized and interpreted in terms of the stretched weak coupling of an octupole 3- phonon. Nearly identical sequences of levels with ?I = 3 and the parity change are found, for the first time, up to 25- for 20 states of 214Ra, up to 35- for 36 states of 212Rn and up to 53/2+ for 16 states of 213Fr. The stretched weak coupling of an octupole phonon is extended up to the highest excitation energy of 11355 keV for 212Rn which has the largest experimental B(E3) value of 44.1(88) W.u. for the 11- ? 82+ transition. The stretched weak coupling of an octupole 3- phonon needs to be considered when single particle configurations are assigned to high spin states. Average octupole excitation energies of 657(51) keV for 211At, 1101(28) keV for 212Rn, 667(25) keV for 213Fr, and 709(25) keV for 214Ra are obtained. The calculated level energies are in a good agreement with the experimental level energies within the error limit of 4.3%. (orig.)

338

Self-assembly of an azobenzene-containing polymer prepared by a multi-component reaction: supramolecular nanospheres with photo-induced deformation properties.  

Science.gov (United States)

In this article, we have synthesized a polymer containing regulated azobenzene groups by one-pot multi-component polymerization (MCP) based on Passerini reaction, and investigated its self-assembly behavior and photo-induced deformation properties. We found that this molecule can form spherical structures with sizes ranging from hundreds of nanometers to several micrometers when dissolved in THF. NMR and FTIR studies indicate that there are associated hydrogen bonds among the molecules in the aggregates, which are responsible for the formation of the nanospheres. By controlling the stirring rate as the THF suspension is dropped into water, the nanospheres can be sorted according to their size. In this way, we have obtained nanospheres with relatively uniform diameter. When irradiated by UV light in the aqueous medium, the nanospheres tend to aggregate into large clusters, while in dry state they are ready to merge into island-like structures, showing a good photo-induced deformation property. PMID:24860850

Wang, Shuai; Zhang, Ning; Ge, Xiaopeng; Wan, Yingbo; Li, Xiaohong; Yan, Li; Xia, Yijun; Song, Bo

2014-07-21

339

Effect of hot deformation on texture and magnetic properties of Sm-Co and Pr-Co alloys  

International Nuclear Information System (INIS)

Nanocrystalline PrCo5, SmCo5 and Sm2(Co,Fe,Mn)17 alloys were subjected to a high-degree plastic deformation at 950 deg. C with the height reduction ranging from 70% to 95%. With increasing degree of deformation, the PrCo5 and SmCo5 magnets showed improvement of the deformation-induced [0 0 1] texture. The PrCo5 alloys, known to develop a superior texture at the lower degrees of deformation, showed only modest improvement and their magnetic performance was undermined by a low coercivity. The SmCo5 alloys had their texture markedly enhanced and, after height reduction by 94.5%, they exhibited a remanence of 8.6 kG, maximum energy product of 18 MGOe and an intrinsic coercivity of 22.8 kOe. No induced texture was found in the alloys based on the Sm2Co17 structure. The microstructures of the hot-deformed alloys were studied with a transmission electron microscopy, and possible mechanisms of the texture development in the RCo5 alloys (R=Pr, Sm) are briefly discussed. - Highlights: ? The effects high-degree deformation were compared for three rare earth-cobalt alloys. ? SmCo5 alloys benefit most from deformation exceeding 90%. ? High-degree deformation slightly improves texture of PrCo5 but damages the coercivity. ? Even the high-degree deformation does not induce texture in alloys based on Sm2Co17.2Co17.

340

Microscopic structure of deformed and superdeformed collective bands in rotating nuclei  

Science.gov (United States)

We investigate in self-consistent cranked Nilsson plus quasiparticle random-phase approximation the structure of Hg190,192,194 in their evolution from normal to superdeformation and from low to high rotational frequencies. The analysis of the energy levels suggests a splitting of few normally deformed bands into two or more branches. The investigation of the dynamical moments of inertia supports the octupole character of the low-lying negative parity superdeformed bands, in agreement with previous theoretical predictions and experimental findings. As a more direct confirm of their octupole nature, we obtain strong E1 transitions linking those bands to the yrast superdeformed band, in agreement with experiments. A similar result is shown to hold also for Dy152. Like in Dy152, the collectivity of the low-lying scissors mode gets enhanced with the onset of superdeformation.

Kvasil, J.; Iudice, N. Lo; Andreozzi, F.; Knapp, F.; Porrino, A.

2007-03-01

341

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  

Energy Technology Data Exchange (ETDEWEB)

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)

Louis, L.

2003-10-15

342

Influence of Heat Treatment Conditions on Microstructure and Mechanical Properties of Austempered Ductile Iron After Dynamic Deformation Test  

Directory of Open Access Journals (Sweden)

Full Text Available In this article, an attempt was made to determine the effect of dynamic load on the austempered ductile iron resistance obtained under different conditions of heat treatment. Tests were carried out on six types of cylindrical ductile iron samples austempered at 320, 370 and 400oC for 30 and 180 minutes. For each type of material, two samples were collected. As a next step in the investigations, the samples were subjected to a Taylor impact test. The samples after striking a non-deformable, rigid target were deformed on their front face. After Taylor test, a series of material tests was performed on these samples, noting a significant increase of hardness in the deformed part. This was particularly well visible in the ductile iron isothermally quenched at higher temperatures of 370 and 400oC. Inthezone of sample deformation, an increase in the content of ferromagnetic phase was also reported, thus indicating the occurrence of martensitic transformation in the microstructure containing mechanically unstable austenite. A significant amount of deformed graphite was also observed, which was a symptom of the deformation process taking place in samples. The ductile iron was characterized by high toughness and high resistance to the effect of dynamic loads, especially as regards the grade treated at a temperature of 370oC.

Myszka D.

2014-10-01

343

Two-phonon octupole excitations in 208Pb: status and perspective  

International Nuclear Information System (INIS)

Progress toward the identification of the two-phonon octupole multiplet in 208Pb is reviewed. Measurements with the 208Pb(n,n'?) reaction have permitted the characterization of a 0+ state at 5241 keV, which decays by a cascade of E3 transitions. Additional measurements with this reaction have led to the identification of candidates for the 2+ and 4+ members of the quartet. Recent inelastic light-ion and neutron transfer reaction studies have led to further clarification of these candidates. In none of these studies or recent Coulomb excitation measurements has a reasonable candidate for the 6+ excitation been identified. Quasiparticle-phonon model calculations of Ponomarev and von Neumann-Cosel seemingly account for all of the observed experimental data and add new information about the fragmentation of these excitations and the possible signatures for their decays

344

Octupole Contributions to the Generalized Oscillator Strengths of Discrete Dipole Transitions in Noble Gases  

CERN Document Server

The generalized oscillator strengths (GOS) of discrete excitations np-nd, both dipole (L=1) and octupole (L=3) are studied, the latter for the first time. We demonstrate that although the relevant transitions in the same atom are closely located in energy, the dependence of their GOS on the momentum transfer q squared, is remarkably different, so that the GOS corresponding to L=3 have at least one extra maximum as a function of q squared and dominate over those of the L=1, starting from about q=1.25$ atomic unit (a.u.). The calculations were performed in the one particle Hartree-Fock approximation and with account of many-electron correlations via the Random Phase Approximation with Exchange. The GOS are studied for values of q squared up to 30 a.u.

Amusia, M Ya; Felfli, Z; Msezane, A Z

2007-01-01

345

Gyromagnetic ratios and octupole collectivity in the structure of the 90-96Zr isotopes  

International Nuclear Information System (INIS)

Shell model calculations have been performed for low-excitation states in the Zr isotopes between 90Zr and 96Zr with an emphasis on the g factors and electromagnetic decay rates for the lowest 2+ and 3- states. Overall the 2+ states are reasonably well described. In contrast, the 3- states present a puzzle because the measured g factors imply a single-particle configuration whereas the experimental E3 transition rates imply collective structures that cannot be explained by shell model calculations. A consistent description of the 3- states in 90Zr and 96Zr is sought in terms of coupling between the single-particle structure and a collective octupole vibration

346

Non-yrast bands in a coherent quadrupole-octupole model  

Energy Technology Data Exchange (ETDEWEB)

A model assuming coherent quadrupole-octupole vibrations and rotations is applied to describe non-yrast energy sequences with alternating parity in several even-even nuclei from different regions. The energies are calculated from an analytically known formula in which for the first time we consider states with arbitrary large quantum numbers, allowing, as a new feature, to describe higher lying bands. A fit of the model parameters is performed for each nucleus in order to reach the best agreement with the experiment. The mass dependence of the parameters will be discussed. The model reproduces the structure of the spectra together with the observed B(E1), B(E2) and B(E3) reduced transition probabilities in the considered nuclei {sup 152,154}Sm, {sup 154,156,158}Gd, {sup 236}U and {sup 100}Mo. Aided by HIC for FAIR.

Strecker, Michael; Lenske, Horst [Institut fuer Theoretische Physik, Universitaet Giessen (Germany); Minkov, Nikolay [Institute of Nuclear Research and Nuclear Energy, Sofia (Bulgaria)

2012-07-01

347

Non-yrast bands in a coherent quadrupole-octupole model  

International Nuclear Information System (INIS)

A model assuming coherent quadrupole-octupole vibrations and rotations is applied to describe non-yrast energy sequences with alternating parity in several even-even nuclei from different regions. The energies are calculated from an analytically known formula in which for the first time we consider states with arbitrary large quantum numbers, allowing, as a new feature, to describe higher lying bands. A fit of the model parameters is performed for each nucleus in order to reach the best agreement with the experiment. The mass dependence of the parameters will be discussed. The model reproduces the structure of the spectra together with the observed B(E1), B(E2) and B(E3) reduced transition probabilities in the considered nuclei 152,154Sm, 154,156,158Gd, 236U and 100Mo. Aided by HIC for FAIR.

348

Enhancement of nuclear Schiff moments and time reversal violation in atoms due to combination of soft nuclear octupole and quadrupole vibrations  

OpenAIRE

Nuclear forces violating parity and time reversal invariance P,T-odd produce P,T-odd nuclear moments, for example, the nuclear Schiff moment. In turn, this moment can induce the electric dipole moment (EDM) in the atom. The contribution to the Schiff moment from the soft collective quadrupole and octupole vibrations in spherical nuclei is calculated in the framework of the quasiparticle random phase approximation with separable quadrupole and octupole forces. The values of n...

Lisetskiy, A. F.; Flambaum, V. V.; Zelevinsky, V. G.

2005-01-01

349

Effect of high-pressure torsion deformation on surface properties and biocompatibility of Ti-50.9 mol. %Ni alloys.  

Science.gov (United States)

Ti-50.9 mol. %Ni was subjected to high-pressure torsion (HPT) deformation for different number of rotations (N) of 0.25, 0.5, 1, 5, and 10. The structural changes induced by HPT were analyzed using x-ray diffractometer (XRD). The surfaces of the samples before and after cell culture were characterized using x-ray photoelectron spectroscopy (XPS). The biocompatibility of the samples was evaluated based on a colony formation assay, nickel ion release, and protein adsorption behavior. XRD analysis revealed the occurrence of grain refinement, phase transformation, and amorphization in the TiNi samples by HPT deformation due to high dislocation density. The changes in chemical composition and thickness of the passive film formed on the surface observed in XPS analysis reveals improvement in the stability of the passive film by HPT deformation. The microstructural change due to the deformation was found to influence the biocompatibility behaviors of TiNi. Plating efficiency and protein adsorption were found to be higher when the samples are in stress-induced martensitic or amorphous state. HPT deformation was found to alter the surface behavior of the TiNi, which effectively reduced the Ni ion release and improved its biocompatibility. PMID:24985211

Awang Shri, Dayangku Noorfazidah; Tsuchiya, Koichi; Yamamoto, Akiko

2014-06-01

350

Isospin dependence of nuclear deformations  

International Nuclear Information System (INIS)

11-MeV neutrons were elastically and inelastically scattered from eight single-closed-shell nuclei: three proton-vibrational nuclei with N = 50 (88Sr, 90Zr, 92Mo) and five even-even neutron-vibrational nuclei (116-124Sn) with Z = 50. Detection methods involving electronic discrimination against ? rays, and time-of-flight techniques were used to measure the energy of the scattered neutrons. Data were taken from 150 to 1500 in 50 intervals. Measured differential cross sections were normalized to the zero-degree neutron flux and corrected. An optical model (OM) analysis was used to fit the elastic data with the code GENOA, and potential parameters were obtained for each nucleus. The observed low-lying electric quadrupole (2+) and octupole (3-) states were collective in nature; the macroscopic or collective model for inelastic scattering was used to generate the differential cross-section angular distributions with the distorted wave method. The deformation parameters and lengths were obtained by normalizing DWUCK calculations to the experimental cross-sections, and were compared to the corresponding (p,p') and electromagnetic values to determine any isospin-dependent effects. A difference was identified in the 2+ parameters, while almost none was seen in the 3- ones

351

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

International Nuclear Information System (INIS)

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)

352

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

353

The influence of severe plastic deformation by high pressure torsion on structure and mechanical properties of Hadfield steel single crystals  

Energy Technology Data Exchange (ETDEWEB)

Hadfield steel single crystals have been deformed by high pressure torsion at room temperature (P=5GPa) for 1, 2, 3 revolutions. The resulting microstructure has been studied by means of transmission electron microscopy (TEM) and X-ray analysis. The size of fragments decreases with increasing number of revolutions due to interaction of slip dislocations, microbands and thin twins. As a result of severe plastic deformation, the microhardness of the Hadfield steel has been increased, and a portion of {epsilon}, {alpha}' martensite has been found.

Zakharova, G G; Astafurova, E G, E-mail: galinazg@yandex.r [Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Sciences, Akademichesky prospect 2/4, 634021, Tomsk (Russian Federation)

2010-07-01

354

The influence of severe plastic deformation by high pressure torsion on structure and mechanical properties of Hadfield steel single crystals  

Science.gov (United States)

Hadfield steel single crystals have been deformed by high pressure torsion at room temperature (P=5GPa) for 1, 2, 3 revolutions. The resulting microstructure has been studied by means of transmission electron microscopy (TEM) and X-ray analysis. The size of fragments decreases with increasing number of revolutions due to interaction of slip dislocations, microbands and thin twins. As a result of severe plastic deformation, the microhardness of the Hadfield steel has been increased, and a portion of epsilon, ?' martensite has been found.

Zakharova, G. G.; Astafurova, E. G.

2010-07-01

355

The influence of severe plastic deformation by high pressure torsion on structure and mechanical properties of Hadfield steel single crystals  

International Nuclear Information System (INIS)

Hadfield steel single crystals have been deformed by high pressure torsion at room temperature (P=5GPa) for 1, 2, 3 revolutions. The resulting microstructure has been studied by means of transmission electron microscopy (TEM) and X-ray analysis. The size of fragments decreases with increasing number of revolutions due to interaction of slip dislocations, microbands and thin twins. As a result of severe plastic deformation, the microhardness of the Hadfield steel has been increased, and a portion of ?, ?' martensite has been found.

356

Structure and mechanical properties of iron after surface severe plastic deformation under friction with simultaneous nitrogen saturation: I. structure formation  

Science.gov (United States)

The structure of armco iron after severe plastic deformation under friction with simultaneous nitrogen saturation has been studied by microstructure analysis, X-ray diffraction, and transmission and scanning electron microscopy. A gradient surface layer, in which the grain size varies from micro- to submicro- and nanometer-scale values, is found to form. A mutual intensifying effect of the deformation-induced refinement of a grain structure and the diffusion of nitrogen atoms in iron is shown. The formation of a nanocrystalline state is discussed as a result of dynamic recrystallization.

Yurkova, A. I.; Mil'man, Yu. V.; Byakova, A. V.

2012-04-01

357

Octupole excitations in 141,144Cs and the pronounced decrease of dipole moments with neutron number in odd-Z neutron-rich 141,143,144Cs  

International Nuclear Information System (INIS)

The level scheme of odd-Z neutron-rich 141Cs (Z=55, N=86) was extended and expanded and that of 144Cs (N=89) was identified for the first time by means of ?-?-? coincidence measurements of prompt ? rays in the spontaneous fission of 252Cf with Gammasphere. Spin/parity was assigned to the levels based on angular correlations and level systematics in 141,143Cs. Parity doublets characteristic of both simplex quantum number s=+i and s=-i were proposed in 141Cs. The tests by using rotational frequency ratio ?-(I)/?+(I) imply octupole vibrations in 141Cs and 143Cs. B(E1)/B(E2) values and electric dipole moments D0 were calculated for 141Cs, and re-determined for 143Cs. It was found that B(E1)/B(E2) values of 141Cs are simplex-dependent and the average value is one order of magnitude larger than that of 143Cs, and the deduced dipole moment D0 of 141Cs is considerably larger than that of 143Cs, and comparable to the N=86 isotone 142Ba. For 144Cs the yrast sequence looks like a well-deformed rotational band, but no octupole band structure was identified in this nucleus. The overall variations of D0 in 141,143,144Cs exhibit a pronounced drop of dipole moment with increasing neutron number in this odd-Z isotopic chain, which may be analogous in nc chain, which may be analogous in nature to the quenching of D0 observed in even-even 146Ba (Z=56, N=90) and 224Ra (Z=88, N=136), and to the drop of D0 in the odd-Z neutron-rich 147La (Z=57, N=90) reported by our collaboration.

358

Nuclear alternating-parity bands and transition rates in a model of coherent quadrupole–octupole motion  

International Nuclear Information System (INIS)

A further extension of a model of coherent quadrupole–octupole vibrations and rotations and its application to alternating-parity spectra in heavy even–even nuclei is presented. Within the model 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 ?-bands and higher negative-parity levels. Electric transition operators reflecting the complex shape characteristics associated with the quadrupole–octupole vibration modes are introduced. By using them B(E1), B(E2) and B(E3) reduced transition probabilities within and between the different energy sequences are calculated. It is shown that the model successfully reproduces yrast and non-yrast alternating-parity bands together with the attendant B(E1)–B(E3) transition rates in the nuclei 154Sm, 156Gd and 100Mo. (author)

359

Indication for a K/sup. pi. / = 0/sup -/ octupole band in /sup 150/Nd from electron scattering  

Energy Technology Data Exchange (ETDEWEB)

Recent electron scattering results on the 0.850 MeV level of /sup 150/Nd, when analyzed in terms of the interacting boson model, are inconsistent with the interpretation of this level as a pure J/sup ..pi../(K) = 2/sup +/(0) state. Very recent (n,n'..gamma..) work has shown this level to be a 1/sup -/, 2/sup +/ doublet. Assuming this level to be the band head of a ''K/sup ..pi../ = 0/sup -/'' octupole band, a simple model is used to predict electron scattering form factors for the 0.850 MeV state and a 3/sup -/ octupole level observed at 0.931 MeV. Comparison is made between these predicted form factors and recent electron scattering data.

Creswell, C.; Hirsch, A.; Bertozzi, W.; Heisenberg, J.; Kowalski, S.; Sargent, C.P.; Turchinetz, W.; Dieperink, A.

1978-11-01

360

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

International Nuclear Information System (INIS)

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 ? ?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.

361

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

Science.gov (United States)

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 ? 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.

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

2012-01-01

362

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

International Nuclear Information System (INIS)

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

363

The effect of cold deformation on the structure, texture and properties of yttrium high temperature superconducting powders and strips  

Energy Technology Data Exchange (ETDEWEB)

Cold deformation of YBa{sub 2}Cu{sub 3}O{sub 7-x}(phase 123, T{sub c} = 88.5-92 K) powders and strips causes partial decomposition of the 123 phase, a reduction in the degree of orthorhombicity of the structure up to almost complete degradation, and a decrease in T{sub c}. When they are deformed, yttrium high temperature superconductors acquire basal (001) (110) texture with high pole density (13-15 arbitrary units), low scattering angle ({+-} 6deg--7deg from the normal direction), and a weak preference for a, b or a + b in the rolling direction; traces of (139) orientations may also be found. This texture is known to be favourable for increasing j{sub k}. The combined effect of cold deformation and a carbon-containing binder leads, however, to a complete loss of superconductivity at 77 K or above. Depending on the regime of subsequent annealing, the following effects may be observed: degradation of the orthorhombic structure with a decrease in T{sub c}; restoration of the orthorhombic structure and T{sub c} of the 123 phase with complete or substantial loss of basal-type texture; change in texture type or retention of the basal texture (P{sup (005)}{sub {alpha}=0} = 6--7 arbitrary units) with restoration of the orthorhombic lattice and T{sub c} of the 123 phase. The appearance of a set of orientations from (139) to (001) in the deformation texture is evidence for the process of recrystallization grain growth. This suggests the appearance of plastic deformation of the ceramics (most probably of the shear type). With long annealing and thermocycling, the basal texture changes in accordance with the theory of compromise recrystallization grain growth up to the restoration of basal texture.

Shamrai, V.F.; Pimenov, A.F.; Efimov, Yu.V.; Babareko, A.A.; Karelin, F.R.; Choporov, V.F.; Frolova, T.M.; Myasnikova, E.A.; Postnikov, A.M. (A.A. Baikov Inst. of Metallurgy, Academy of Sciences, Moscow (Russia))

1991-09-20

364

Deformation potentials in AlGaN and InGaN alloys and their impact on optical polarization properties of nitride quantum wells  

DEFF Research Database (Denmark)

The deformation potentials acz?D1, act?D2, D3, D4, and D5 are determined for random AlGaN and InGaN alloys using electronic band structure calculations based on the density functional theory. A sublinear composition dependence is obtained for acz?D1 and D3 in AlGaN, and D3 in InGaN, whereas superlinear behavior on composition is found foract?D2, D4, and D5 in AlGaN, and act?D2and D5 in InGaN. The optical polarization properties of nitride quantum wells are very well described by the k·p method when the obtained deformation potentials are included. In m-plane AlGaN/AlN and InGaN/GaN quantum wells, the difference between the interband transition energies for light polarized parallel and orthogonal to the crystalline c axis compares more favorably to experimental data, than when deformation potentials previously reported in literature are used.

?epkowski, S. P.; Gorczyca, I.

2013-01-01

365

Tetrahedral and Triangular Deformations of $Z=N$ Nuclei in Mass Region $A \\sim 60-80$  

OpenAIRE

We study static non-axial octupole deformations in proton-rich $Z=N$ nuclei, $^{64}$Ge, $^{68}$Se, $^{72}$Kr, $^{76}$Sr, $^{80}$Zr and $^{84}$Mo, by using the Skyrme Hartree-Fock plus BCS calculation with no restrictions on the nuclear shape. The calculation predicts that the oblate ground state in $^{68}$Se is extremely soft for the $Y_{33}$ triangular deformation, and that in $^{80}$Zr the low-lying local minimum state coexisting with the prolate ground state has the $Y_{3...

Takami, S.; Yabana, K.; Matsuo, M.

1997-01-01

366

Description of low-lying vibrational K? ? 0+ states of deformed nuclei in the quasiparticle-phonon nuclear model  

International Nuclear Information System (INIS)

The QPNM equations are derived taking account of p-h and p-p interactions. The calculated quadrupole, octupole and hexadecapole vibrational states in 168Er, 172Yb and 178Hf are found to be reasonale agreement with experimental data. It is shown that distribution of the E? strength in some deformed nuclei differs from the standard one. There are cases when for a given K? and E? strength is concentrated not on the first but on higher-lying states. The assertion made earlier about the absence of collective two-phonon states in deformed nuclei is confirmed. 44 refs.; 1 fig.; 6 tabs

367

Effect of deuterium pre-charging on the mechanical properties, phase and deformation texture of 21-6-9 austenitic stainless steel  

International Nuclear Information System (INIS)

The internal deuterium was introduced prior to tension test to 21-6-9 austenitic stainless steel by the thermal charging method. Effects of deuterium pre-charging on mechanical properties of 21-6-9 steel was investigated and the mechanism was discussed. Compared with the unprecharged tensile bars, the ductility decreased significantly and the fracture morphology showed brittle features in deuterium precharged ones. This damage has little relation with strain-induced ?? martensite transformation in this steel. But it is probably due to the deformation manner altered by internal deuterium

368

Effect of deformation degree in cold rolling on texture and properties of welded joints of zirconium alloy with 2.5 % Nb  

International Nuclear Information System (INIS)

Changes of welded joint texture of 2.5% niobium zirconium alloy made with arc welding in helium have been investigated during cold rolling of samples with total squeezing of up to 95 %. It is shown that to eliminate texture inhomogeneity, it is necessary to roll the joints with squeezing > 60%. Cold deformation of welded joints decreases inhomogeneity of metal physical properties of different zones. At that structural inhomogeneity remains, which is related to the distinction of structural states of main metal, weld and heat affected zone in an initial before rolling state

369

Effect of one-axis deformation on Cd2Nb2O7 dielectric relaxation and pyroelectric properties in the 100-300 K temperature range  

International Nuclear Information System (INIS)

The effect of one-axis deformation on dielectric relaxation and pyroelectric properties of Cd2Nb2O7 in the 100-300 K temperature range is studied. For the first time a profound variation of the temperature dependence of permittivity and the pyroelectric coefficient of this compound when applying one-axis mechanical stress have been discovered. The obtained results have shown that in the 100-196 K temperature range Cd2Nb2O7 is a ferroelectric and a ferroelastic at the same time, and even small mechanical stress increases the upper boundary of the given range

370

q-Deformed Dynamics and Virial Theorem  

OpenAIRE

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.

Zhang, Jian-zu

2002-01-01

371

Deformed Dynamics of Q-Deformed Systems  

International Nuclear Information System (INIS)

Quantum algebras have been the subject of an intensively research in the last years. Particularly, after the works of Macfarlane and Biedenharn on the q-deformed oscillators, a great effort has been devoted to the application and generalization of q-deformed systems in chemistry and physics. In quantum optics, q-bosons have been used to generalized fundamental models such as, the Jaynes-Cummings and Dicke models. Besides, using generalized deformed oscillators several versions of the Jaynes-Cummings Hamiltonian have found a unified description. In the present work, we study the dynamical properties of q-deformed oscillators and their relationship to the anharmonic oscillators by means of a Lie-algebraic approach. In doing so, we find that an infinite dimensional set of 'q-deformed relevant operators' close a 'partial q-deformed Lie algebra' under commutation with the Arik-Coon Hamiltonian. We show that the dynamics of the s?stem can be described in terms of the multi commutator of the type [H,... , [H, 0] . . .]. Eve also obtain, that the multi commutator can be expressed for q > 1 as an operator average with respect to the ('Binomial distribution' which depends on[g on the deformation parameter q, and for the general case (i.e. q - R) as a 'power law'. As a consequence of the power law dependence, we find that the dynamics of the infinite-dimensional q-deformed Lie-algebra scale, i.e. the temporal evolution for the whole set of relevant operators collapse on a single curve. We calculate and analyze, the temporal evolution of the set of relevant operators for the q-deformed and the anharmonic oscillator when the initial conditions are a q-coherent and coherent states respectively. We obtain that the dynamics of both models is governed by a weighted average with respect to the 'q-deformed Poisson' and the 'standard Poisson' distributions respectively. Finally, we find the conditions under which the dynamics of the relevant operators of both oscillators are isomorphous, and we conclude that q is not only related to the anharmonicity parameter but also depends on the index that characterizes the relevant operators

372

Hot tensile properties and deformation reponse of a ?(Ni)/?'(Ni3Al)--delta(Ni3Nb) eutectic composite  

International Nuclear Information System (INIS)

Three distinct regions of tensile, deformation and fracture behavior were observed in a 2.5 wt% Al ?/?'-delta eutectic alloy as the testing temperature was varied. The major finding was an extraordinary ductility maximum at about 5500C. It was shown that this phenomenon is caused by the deflection of transverse cracks at the eutectic grain boundaries when yielding occurs. This delamination between eutectic grains caused by fracture of a ?' eutectic grain boundary film leads to a distinctly different ''wood-like'' fracture surface morphology. Above 6900C to 9260C, yield and tensile strength values decrease while ductility increases slightly. Cooperative twinning of both phases develops giving rise to block-like deformation of the microstructure quite in parallel to the behavior observed previously in the ?-delta system

373

Search for two-phonon octupole vibrational bands in 88,89,92,93,94,96Sr and 95,96,97,98Zr  

International Nuclear Information System (INIS)

Several new gamma transitions were identified in 94Sr, 93Sr, 92Sr, 96Zr and 97Zr from the spontaneous fission of 252Cf. Excited states in 88,89,92,94,96Sr and 95,96,97,98Zr were reanalyzed and reorganized to propose the new two-phonon octupole vibrational states and bands. The spin and parity of 6+ are assigned to a 4034.5 keV state in 94Sr and 3576.4 keV state in 98Zr. These states are proposed as the two-phonon octupole vibrational states along with the 6+ states at 3483.4 keV in 96Zr, at 3786.0 keV in 92Sr and 3604.2 keV in 96Sr. The positive parity bands in 88,94,96Sr and 96,98Zr are the first two-phonon octupole vibrational bands based on a 6+ state assigned in spherical nuclei. It is thought that in 94,96Sr and 96,98Zr a 3- octupole vibrational phonon is weakly coupled to an one-phonon octupole vibrational band to make the two-phonon octupole vibrational band. Also, the high spin states of odd-A95Zr and 97Zr are interpreted to be generated by the neutron 2d5/2 hole and neutron 1g7/2 particle, respectively, weakly coupled to one- and two-phonon octupole vibrational bands of 96Zr. The high spin states of odd-A87Sr are interpreted to be caused by the neutron 1g9/2 hole weakly coupled to 3- and 5- states of 88Sr. New one- and two-POV bands in 95,97Zr and 87,89Sr are proposed, for the first time, in the present work. (author)

374

Some unusal properties of the fine structure of dislocations in Ni{sub 3}Al deformed at high temperature  

Energy Technology Data Exchange (ETDEWEB)

In Ni{sub 3}Al polycrystals deformed at 850{degrees}C and quenched rapidly, surface defects exhibit two kinds of behaviour. On the one hand, dislocation coupling by antiphase boundary (APB) and complex stacking fault (CSF) is of normal magnitude for this alloy composition. On the other hand, separations are dramatically decreased in both cases. A method to visualize antiphase boundaries using a weakly excited superlattice reflection is introduced.

Veyssiere, P. [Office National d`Etudes et de Recherches Aerospatiales (ONERA), 92 - Chatillon (France); Horton, J.A. [Oak Ridge National Lab., TN (United States)

1994-12-31

375

Influence of Microstructure, Produced by Heat Treatment and Sever Plastic Deformation, on Tribological Properties of Low-carbon Steel  

OpenAIRE

This paper presents the results of tribological investigations conducted on steel 20 with the carbon content of up to 0.2%. The steel was studied in the three conditions: initial (hot-rolled), after heat-treatment (quenching+tempering) and after heat treatment with subsequent severe plastic deformation (SPD) performed by equal channel angular pressing technique (ECAP). It was stated that after various treatments the material acquires various structural conditions and possesses various stren...

Semenov, V. I.; -j Huang, S.; Sh Shuster, L.; -c Lin, P.

2011-01-01

376

Optical and wetting properties of nanostructured fluorinated ethylene propylene changed by mechanical deformation and its application in triboelectric nanogenerators  

Science.gov (United States)

We demonstrate that nanostructured fluorinated ethylene propylene (FEP) polymer films undergo a non-reversible structural transition when exposed to an applied force. While reactive ion etching (RIE) treatment creates FEP films with well-defined nanostructures, applied stress causes a permanent deformation which alters the optical reflectance spectrum. The structural changes of the FEP films also altered the contact angles of water droplets. It was found that the contact angles changed from 109° before to 139° after RIE treatment, and plastic deformation reduced the contact angles to 111°. Scanning electron microscopy images revealed freshly formed homogeneous surfaces, with nanostructures hidden below, which correlated with the macroscopic changes in optical reflectance. Interestingly, the contact electrification between FEP and aluminum did not change when the nanostructures were deformed, and we propose that the nanostructured FEP surface can be used to both optically monitor the state of the nanostructure as well as functioning as a part of an energy harvesting system. At an average power of about 22 ?W with an area of 4 cm2, the energy harvester is able to light up a large number of light emitting diodes.

Guo, Xiaodong; Helseth, Lars Egil

2015-01-01

377

Melt-rock interactions, deformation, hydration and seismic properties in the sub-arc lithospheric mantle inferred from xenoliths from seamounts near Lihir, Papua New Guinea  

Science.gov (United States)

This study analyses the interactions between deformation and reactive fluid and melt percolation, and their effects on sub-arc mantle seismic properties based on microstructural observations on mantle xenoliths extracted by the Tubaf and Edison seamounts close to the Lihir Island, in the Papua New Guinea archipelago. These xenoliths sample an oceanic lithosphere, which has experienced high-temperature deformation in the presence of fluids or melts. This was followed by metasomatism under static conditions. Syn-kinematic percolation of reactive Si-rich melts or fluids in peridotites has produced pyroxene-enrichment, grain size reduction, and dispersion of olivine crystal preferred orientation (CPO). Fourier transform infrared spectroscopy analyses show that olivine has very low water contents (1-4 wt. ppm H2O), similar to spinel peridotites from other subduction zones. These low values may record both low water solubility in olivine at low pressure and dehydration during transport and exhumation. Water contents in pyroxenes are highly variable and likely result from spatially heterogeneous melt or fluid percolation. Analysis of olivine CPO indicates dominant activation of both (010)[100] and (001)[100] slip systems, which are characteristic of deformation under high temperature, low stress, low pressure and low to moderate hydrous conditions. Fast S-wave polarization and P- and Rayleigh propagation directions are thus parallel to the mantle flow direction. The pyroxene enrichment by melt-rock reactions is accompanied by dispersion of olivine CPO and induces a significant decrease of the maximum S-wave and P-wave anisotropy in the peridotites. The calculated seismic properties also show that the lowest Vp/Vs ratios (< 1.7) mapped in fore-arc mantle may only be explained by taking in consideration the CPO-induced elastic anisotropy of the peridotites.

Soustelle, Vincent; Tommasi, Andréa; Demouchy, Sylvie; Franz, Leander

2013-11-01

378

Fragmentation of the two-phonon octupole vibrational states in 208Pb  

International Nuclear Information System (INIS)

An experiment designed to populate two-phonon vibrational states in 208Pb by Coulomb excitation was performed with a 136Xe beam at a bombarding energy of 650 MeV. The ? rays from the decay of the excited states were measured with Gammasphere and scattered particles were detected in the compact heavy-ion counter CHICO. We have not been able to observe any state close to the expected harmonic energy of 5.2 MeV. However, we were able to extract the B(E3,31-?61+) value for the lowest known 6+ state at 4.424 MeV based on measured ?-ray intensities. About 20% of the expected total E3 strength can be found in this state, suggesting a large fragmentation of this second octupole phonon state in 208Pb. Upper limits for the B(E3) strength were determined for higher-lying, but unseen, 6+ states ranging from 15% of the harmonic value at 5.2 MeV to 100% at 6.0 MeV. copyright 1998 The American Physical Society

379

Space charge and octupole driven resonance trapping observed at the CERN proton synchrotron  

CERN Document Server

The combined effect of space charge and nonlinear resonance on beam loss and emittance was measured in a benchmarking experiment over a 1.2 s long flat bottom at 1.4 GeV kinetic energy in the presence of a single controllable octupole. By lowering the working point towards the resonance, a gradual transition from a loss-free core emittance blowup to a regime dominated by continuous loss was found. We compare the observation with 3D simulations based on a new analytical space charge model and obtain good agreement in the emittance blowup regime. Our explanation is in terms of the synchrotron oscillation, which causes a periodic tune modulation due to space charge, and leads to trapping and detrapping on the resonance islands. For working points very close to the resonance this induces a beam halo with large radius. The underlying dynamics is studied in detail, and it is claimed that the predicted halo in conjunction with a reduced dynamic aperture for the real machine lattice is the source of the loss observed...

Franchetti, Giuliano; Giovannozzi, Massimo; Martini, Michel; Métral, Elias; 10.1103/PhysRevSTAB.6.124201

2003-01-01

380

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1995-08-01

381

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

CERN Multimedia

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.

382

Influence of annealing and deformation on optical properties of ultra precision diamond turned and anodized 6060 aluminium alloy  

DEFF Research Database (Denmark)

Influence of cold forging, and subsequent heat treatment and diamond turning on optical quality of anodized film on 6060 (AlMgSi) alloy was investigated and compared with microstructural changes. Heat treatment of the samples was carried out either prior to forging, post-forging, or both. The surface of the forged material was then diamond turned to a mirror like finish. The diamond turned samples were subsequently anodized in a sulphuric acid bath. The microstructure of the samples was analysed using optical microscopy (LOM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Colour/brightness measurements were carried out using CIE Lab system. An optical method was used to measure the thickness of the oxide film and roughness of the surface was measured before and after anodizing using stylus, a mechanical instrument, and bidirectional reflection distribution function (BRDF), an optical instrument. Results indicated that the post-forging heat treatment had a great influence on the appearance of the anodized layer, which was also a function of the deformation introduced prior to heat treatment. The effect was assumed to be attributed to the change in microstructure, especially the distribution and the amount of the intermetallic particles such as elemental Si and Mg2Si. Roughness of the oxide film was also found to be a function of the heat treatment and deformation condition.

Tabrizian-Ghalehno, Naja; Hansen, Hans NØrgaard

2010-01-01

383

Deformation and electrical properties of magnetic and vertically conductive composites with a chain-of-spheres structure  

Science.gov (United States)

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.

Choi, Chulmin; Hong, Soonkook; Chen, Li-Han; Liu, Chin-Hung; Choi, Duyoung; Kuru, Cihan; Jin, Sungho

2014-05-01

384

Measurements of octupole collectivity in $^{220,222}$Rn and $^{222,224}$Ra using Coulomb excitation  

CERN Multimedia

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.

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

385

Isotope effects of the isoscalar octupole resonance on sup(58,62)Ni and sup(90,92)Zr  

International Nuclear Information System (INIS)

Structure corresponding to a LEOR was observed on sup(58,62)Ni and sup(90,92)Zr in the (?, ?') reactions at E sub(?) = 65 MeV, respectively. It was found in the present experiment that about 25% of the isoscalar octupole EWSR (including the lowest 3- state) is exhausted for all the targets, however, the partitioning of EWSR strength between LEOR and the lowest 3- state vary with a small change of outer nucleons on Ni and Zr isotopes. The observed weighted mean excitation energy indicates obviously isotope dependence. (author)

386

New kinds of deformed Bessel functions  

OpenAIRE

Using a deformed calculus based on the Dunkl operator, two new deformations of Bessel functions are proposed. Some properties i.e. generating function, differential-difference equation, recursive relations, Poisson formula... are also given with detailed proofs. Three more deformations are also outlined in the last section.

Zahaf, Mohammed Brahim; Manchon, Dominique

2013-01-01

387

Structural defects in Fe–Pd-based ferromagnetic shape memory alloys: tuning transformation properties by ion irradiation and severe plastic deformation  

International Nuclear Information System (INIS)

Fe–Pd-based ferromagnetic shape memory alloys constitute an exciting class of magnetically switchable smart materials that reveal excellent mechanical properties and biocompatibility. However, their application is severely hampered by a lack of understanding of the physics at the atomic scale. A many-body potential is presented that matched ab inito calculations and can account for the energetics of martensite ? austenite transition along the Bain path and relative phase stabilities in the ordered and disordered phases of Fe–Pd. Employed in massively parallel classical molecular dynamics simulations, the impact of order/disorder, point defects and severe plastic deformation in the presence of single- and polycrystalline microstructures are explored as a function of temperature. The model predictions are in agreement with experiments on phase changes induced by ion irradiation, cold rolling and hammering, which are also presented. (paper)

388

Structural defects in Fe-Pd-based ferromagnetic shape memory alloys: tuning transformation properties by ion irradiation and severe plastic deformation  

Science.gov (United States)

Fe-Pd-based ferromagnetic shape memory alloys constitute an exciting class of magnetically switchable smart materials that reveal excellent mechanical properties and biocompatibility. However, their application is severely hampered by a lack of understanding of the physics at the atomic scale. A many-body potential is presented that matched ab inito calculations and can account for the energetics of martensite \\leftrightarrow austenite transition along the Bain path and relative phase stabilities in the ordered and disordered phases of Fe-Pd. Employed in massively parallel classical molecular dynamics simulations, the impact of order/disorder, point defects and severe plastic deformation in the presence of single- and polycrystalline microstructures are explored as a function of temperature. The model predictions are in agreement with experiments on phase changes induced by ion irradiation, cold rolling and hammering, which are also presented.

Mayr, S. G.; Arabi-Hashemi, A.

2012-10-01

389

Tuning the electronic properties of boron nitride nanotube by mechanical uni-axial deformation: a DFT study  

OpenAIRE

Abstract The effect of uni-axial strain on the electronic properties of (8,0) zigzag and (5,5) armchair boron nitride nanotubes (BNNT) is addressed by density functional theory calculation. The stress-strain profiles indicate that these two BNNTS of differing types display very similar mechanical properties, but there are variations in HOMO-LUMO gaps at different strains, indicating that the electronic properties of BNNTs not only depend on uni-axial strain, but on BNNT type. The va...

Ju Shin-Pon; Wang Yao-Chun; Lien Ting-Wei

2011-01-01

390

Deformable shell model  

International Nuclear Information System (INIS)

Several improvements on the shell model have recently been suggested to explain the additional effective many body interaction in the study of lattice dynamics of ionic crystals. The deformable shell model (DSM) is one such. Hence, the explicit expression of a three body interaction is obtained by assuming that the free ion electron shell suffers a scalar deformation when put in a crystal. It may be said so using the language of perturbation theory. This three body interaction is interpreted as a second order exchange effect while that of Lundquist is a first order exchange effect. Applying the three body interaction in the deformable shell model it has been possible to make comprehensive calculations of both the static and dynamic properties of a solid once the potential parameters are fixed. It is interesting to note that in such comprehensive calculations for the six ionic crystals so far done using the deformable shell model no major disagreement with experiment has yet come out. Detailed calculations on six potassium and rubidium halides show that phase transition phenomena are well explained . Equations of state calculated upto very high pressures in the second phase have been found to agree with experiment. In these calculations the parameters of the potential are obtained from the properties of the first phase. Such results generate some confidence in the potential function and its parameters and show that it can be used as a guide for predicting the propertieed as a guide for predicting the properties of the second phase. Such a comprehensive calculation for the NaCl phase of TIBr crystal has recently been completed in the frame-work of the deformable shell model, from its properties in the CsCl phase. (author)

391

Exotic Collective Excitations at High Spin: Triaxial Rotation and Octupole Condensation  

OpenAIRE

In this thesis work, two topics, triaxiality and reflection asymmetry, have been discussed. Band structures in $^{163}$Tm were studied in a "thin" target experiment as well as in a DSAM lifetime measurement. Two new excited bands were shown to be characterized by a deformation larger than that of the yrast sequence. These structures have been interpreted as Triaxial Strongly Deformed bands associated with particle-hole excitations, rather than with wobbling. Moreover, the Ti...

Wang, Xiaofeng

2008-01-01

392

Correlation of substructure with mechanical properties of plastically deformed reactor structural materials. Progress report, January 1, 1976--June 30, 1977  

International Nuclear Information System (INIS)

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

393

Correlation of substructure with mechanical properties of plastically deformed reactor structural materials. Progress report, January 1, 1976--June 30, 1977  

Energy Technology Data Exchange (ETDEWEB)

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)/sup -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 /sup 1///sub 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.

Moteff, J.

1977-07-08

394

Evolution of quadrupole and octupole collectivity north-east of $^{132}$ Sn: the event Te and Xe isotopes  

CERN Multimedia

We propose to study excited states in isotopes north-east of the doubly-magic 132Sn 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}({E}$3) 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 pro...

395

Influence of austenization parameters on physical-mechanical properties of noniradiated and neutron-irradiated 12Cr18Ni10Ti steel deformed in temperature interval 25-100 oC  

International Nuclear Information System (INIS)

The influence of austenization temperature on characteristics of hardness, ductility and magnetic properties of non-irradiated and irradiated with neutrons 12Cr18Ni10Ti steel was investigated. It was shown that a decrease in austenization temperature from 1150 to 1050 oC results in a negative impact on martensitic ???' transformation at cold deformation.

396

Accretion onto stars with octupole magnetic fields: Matter flow, hot spots and phase shifts  

Science.gov (United States)

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. Investigation of accretion onto such stars requires global three-dimensional (3D) magnetohydrodynamic (MHD) simulations, where the complexity of simulations strongly increases with each higher-order multipole. Previously, we were able to model disc accretion onto stars with magnetic fields described by a superposition of dipole and quadrupole moments. However, in some stars, like CTTS V2129 Oph and BP Tau, the octupolar component is significant and it was necessary to include the next octupolar component. Here, we show results of global 3D MHD simulations of accretion onto stars with superposition of the dipole and octupole fields, where we vary the ratio between components. Simulations show that if octupolar field strongly dominates at the disc-magnetosphere boundary, then matter flows into the ring-like octupolar poles, forming ring-shape spots at the surface of the star above and below equator. The light-curves are complex and may have two peaks per period. In case where the dipole field dominates, matter accretes in two ordered funnel streams towards poles, however the polar spots are meridionally-elongated due to the action of the octupolar component. In the case when the fields are of similar strengths, both, polar and belt-like spots are present. In many cases the light-curves show the evidence of complex fields, excluding the cases of small inclinations angles, where sinusoidal light-curve is observed and 'hides' the information about the field complexity. We also propose new mechanisms of phase shift in stars with complex magnetic fields. We suggest that the phase shifts can be connected with: (1) temporal variation of the star's intrinsic magnetic field and subsequent redistribution of main magnetic poles; (2) variation of the accretion rate, which causes the disc to interact with the magnetic fields associated with different magnetic moments. We use our model to demonstrate these phase shift mechanisms, and we discuss possible applications of these mechanisms to accreting millisecond pulsars and young stars.

Long, Min; Romanova, Marina M.; Lamb, Frederick K.

2012-02-01

397

Fragmentation of giant multipole resonances in deformed nuclei  

International Nuclear Information System (INIS)

The fragmentation of the giant monopole resonance in deformed nuclei is first studied by coupling the monopole oscillation with the quadrupole oscillation by means of the variational procedure for resonance frequencies. It is shown that, for non-axial symmetry, the monopole oscillation couples with both m = 0 and 2 modes of the quadrupole oscillation and the giant monopole resonance is split into three components, whereas for axial symmetry, the fragmentation is given by E0(1+0.86delta2-+1.25delta3) and E0(0.74-+0.22delta-0.21delta2+-0.57delta3), where E0 is the giant monopole resonance energy for spherical nuclei, delta is the deformation parameter, and the upper and lower signs stand for prolate and oblate deformations, respectively. The initial fragmentation of the giant quadrupole resonance is seen to be little modified by the coupling, except for the 7 = 0 mode which is split into two components. The variational method is extended to general multipoles for an ellipsoid and the fragmentation of giant multipole resonances in deformed nuclei is investigated for both axial and non-axial symmetries. A brief discussion is also made about the meaning of the energy eigenvalue involved in the model wave equation in terms of multipole sum rules. The giant dipole resonance for the static octupole deformation is shortly considered. The giant E0 and E3 resonances for largely deformed nuclei are finalnces for largely deformed nuclei are finally examined by solving the spheroidal eigenvalue equation and they are compared with the results of the giant dipole and quadrupole resonances. (orig.)

398

Composition Dependence of Phase Stability, Deformation Mechanisms, and Mechanical Properties of the CoCrFeMnNi High-Entropy Alloy System  

Science.gov (United States)

The proposal of configurational entropy maximization to produce massive solid-solution (SS)-strengthened, single-phase high-entropy alloy (HEA) systems has gained much scientific interest. Although most of this interest focuses on the basic role of configurational entropy in SS formability, setting future research directions also requires the overall property benefits of massive SS strengthening to be carefully investigated. To this end, taking the most promising CoCrFeMnNi HEA system as the starting point, we investigate SS formability, deformation mechanisms, and the achievable mechanical property ranges of different compositions and microstructural states. A comparative assessment of the results with respect to room temperature behavior of binary Fe-Mn alloys reveals only limited benefits of massive SS formation. Nevertheless, the results also clarify that the compositional requirements in this alloy system to stabilize the face-centered cubic (fcc) SS are sufficiently relaxed to allow considering nonequiatomic compositions and exploring improved strength-ductility combinations at reduced alloying costs.

Tasan, C. C.; Deng, Y.; Pradeep, K. G.; Yao, M. J.; Springer, H.; Raabe, D.

2014-10-01

399

Electronic properties and drift of nonequilibrium charge carriers in Si and GaAs semiconductor structures under alternating-strain-induced deformation  

International Nuclear Information System (INIS)

Full text: It is well known that the drift of nonequilibrium charge carriers in the semiconductors is one of the basic processes determining the efficiency of solar cells, nuclear radiation detectors and other semiconductor devices. Therefore at present article the processes of drift of nonequilibrium charge carriers in nonepiezosemiconductors (Si) and piezosemiconductors (GaAs) structures were studied. As alternating-strain-induced deformation used the longitudinal ultrasonic waves with variable amplitude and a frequency ranging within f = 10; 50 MHz were generated by a quartz transducer acoustically coupled to a cathode contact of the photodetector. The electric voltage to the quartz transducer was supplied from an HF generator. It is shown that the alternating-strain-induced deformation fields significantly influence the transport of charge carriers and photoelectrical properties of Si and GaAs semiconductor structures with traps and heterogeneity. The amplitude characteristics of the semiconductors were measured on a special setup for the amplitude analysis, which allowed the collected charge to be estimated with high accuracy. After the electron hole pair generation, the sample featured the motion of nonequilibrium charge carriers.It is shown that during the drift of electrons through the crystal, the current slightly changing as a result of trapping of a part of the nonequilibrium carriers by traps. If the sample was subjected to the action of ultrasonic waves, dependence of the signal amplitude on the field strength was described complex form which the physical reasons of this behavior were considered in the present article. Besides for comparison it was study of the photoelectrical, reflection and spectral characteristics of nonepiezosemiconductor and piezosemiconductors. (authors)

400

One-phonon octupole vibrational states in {sup 211}At, {sup 212}Rn, {sup 213}Fr and {sup 214}Ra with N = 126  

Energy Technology Data Exchange (ETDEWEB)

Excited high spin states in {sup 211}At, {sup 212}Rn, {sup 213}Fr and {sup 214}Ra with N = 126 are reorganized and interpreted in terms of the stretched weak coupling of an octupole 3{sup -} phonon. Nearly identical sequences of levels with {Delta}I = 3 and the parity change are found, for the first time, up to 25{sup -} for 20 states of {sup 214}Ra, up to 35{sup -} for 36 states of {sup 212}Rn and up to 53/2{sup +} for 16 states of {sup 213}Fr. The stretched weak coupling of an octupole phonon is extended up to the highest excitation energy of 11355 keV for {sup 212}Rn which has the largest experimental B(E3) value of 44.1(88) W.u. for the 11{sup -} {yields} 8{sub 2}{sup +} transition. The stretched weak coupling of an octupole 3{sup -} phonon needs to be considered when single particle configurations are assigned to high spin states. Average octupole excitation energies of 657(51) keV for {sup 211}At, 1101(28) keV for {sup 212}Rn, 667(25) keV for {sup 213}Fr, and 709(25) keV for {sup 214}Ra are obtained. The calculated level energies are in a good agreement with the experimental level energies within the error limit of 4.3%. (orig.)

Hwang, J.K.; Hamilton, J.H.; Ramayya, A.V. [Vanderbilt University, Physics Department, Nashville, TN (United States)

2013-12-15

401

Deformation properties of even-even Os, Pt, Hg nuclei and spectroscopic properties of odd Re, Os, Ir, Pt, Au, Hg nuclei from self-consistent calculations  

International Nuclear Information System (INIS)

Static properties of even-even Os, Pt, Hg nuclei have been obtained from HF + BCS calculations. Single-particle wave functions which come from these self-consistent calculations have been used to calculate some spectroscopic properties of odd Re, Os, Ir, Pt, Au and Hg nuclei, within the rotor + quasiparticle coupling model. Our calculations are able to give a good description of most of available experimental data. (orig.)

402

Deforming beds: Viscous and plastic scales of deformation  

Science.gov (United States)

Small scale field and laboratory observations of sub-glacial sediment deformation suggest that failure is the predominant method of sediment deformation, while large scale modelling studies using a viscous model of till deformation have been reasonably successful in predicting the geological consequences of ice sheet action. This suggests that the cross-over scale between viscous and plastic deformation occurs at a much larger scale than the grain-grain interaction scale previously thought to be appropriate to deforming till. Sediment deformation and the drainage of sub-glacial areas are considered at different scales, and how these interact to produce failure and viscous behaviour is discussed. A fluctuation length scale is proposed, whose horizontal dimensions are of the order of the depth of the base of deformation (1-10 m). On this length scale, the glacier/deforming bed system is highly variable in time as well as in space. Till deformation occurring at this length scale is plastic, happening though failure events. Three other specific scales are proposed, whose different properties depend on the relative spatial variability of static and seepage pressures and topography. The key theoretical problem which has yet to be solved is how multiple small scale failure events combine into a viscous type flow. This is discussed in the context of self-organised criticality. It is argued that the length scales appropriate for some drainage features are not appreciably larger than the scale for plastic failure events, implying that modelling sub-glacial drainage channels by balancing erosion rates against viscous closure of the channel is misconceived. The outlines of an alternative model involving percolation theory are presented. Certain key questions which can only be settled through observations by glaciologists and glacial geologists are discussed. It is suggested that the difference between lodgement tills and deformation tills reflects the rate of motion of till by deformation, and that lodgement from the ice is unimportant.

Hindmarsh, Richard

403

Characteristic temperature of deformation of crystalline materials  

International Nuclear Information System (INIS)

Using the concept of a characteristic deformation temperature, t* (knee temperature), below which the Peierls-Nabarro stress becomes significant, some general regularities have been determined on the influence of temperature upon structural state and mechanical properties of crystalline materials. It is demonstrated that t* represents a natural boundary between the intervals of warm and cold deformation. At the temperature t*, the mechanisms of deformation, fracture, and recovery of properties in annealing vary significantly in the same manner for different crystals. (author)

404

An Investigation of Physico-Mechanical Properties of Ultrafine-Grained Magnesium Alloys Subjected to Severe Plastic Deformation  

Science.gov (United States)

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.

Kozulyn, A. A.; Skripnyak, V. A.; Krasnoveikin, V. A.; Skripnyak, V. V.; Karavatskii, A. K.

2015-01-01

405

One-phonon octupole vibrational states in 136Xe, 137Cs, 138Ba, 140Ce and 142Nd with N = 82  

International Nuclear Information System (INIS)

Excited high spin states in 136Xe, 137Cs, 138Ba, 140Ce and 142Nd with N = 82 are reorganized and interpreted in terms of the weak coupling mode of an octupole 3- phonon. Nearly identical sequences of levels with ?I = 3 and ?? = yes built on 17/2+ and 23/2- states are found, for the first time, up to 29/2+ and 35/2-, respectively, for 22 states of 137Cs. Also, nearly identical sequences of levels with ?I = 3 and ?? = yes built on the 6+ and 9- states are found, for the first time, up to 14+ and 17-, respectively, for 18 states of 136Xe, up to 14+ and 17-, respectively, for 24 states of 138Ba and up to 11+ and 14-, respectively, for 14 states of 140Ce. New spins and parities are assigned, tentatively, to the high spin states of these nuclei based on the weak coupling mode of an octupole 3- phonon. The weak coupling of an octupole 3- phonon needs to be considered when single particle configurations are assigned to high spin states. Neutron particle-hole states (?h11/2-1 f7/2+1) with weak coupling of an octupole 3- phonon are proposed, for the first time. The ?h11/2-1 f7/2+1 excitation energies (Eext(1p1h)) are nearly constant with increasing of Z. One-phonon excited states in 136Xe, 137Cs, 138Ba and 140Ce have the stretched weak coupling configurations of ?I = 3. But one-phonon excited states in 142Nd show the non-stretched weak coupling configurations of an octupole phonon with ?I = 3 and 2. (orig.)

406

Deformed Calabi-Yau Completions  

CERN Document Server

We define and investigate deformed n-Calabi-Yau completions of homologically smooth differential graded (=dg) categories. Important examples are: deformed preprojective algebras of connected non Dynkin quivers, Ginzburg dg algebras associated to quivers with potentials and dg categories associated to the category of coherent sheaves on the canonical bundle of a smooth variety. We show that deformed Calabi-Yau completions do have the Calabi-Yau property and that their construction is compatible with derived equivalences and with localizations. In particular, Ginzburg dg algebras have the Calabi-Yau property. We show that deformed 3-Calabi-Yau completions of algebras of global dimension at most 2 are quasi-isomorphic to Ginzburg dg algebras and apply this to the study of cluster-tilted algebras and to the construction of derived equivalences associated to mutations of quivers with potentials. In the appendix, Michel Van den Bergh uses non commutative differential geometry to give an alternative proof of the fac...

Keller, Bernhard

2009-01-01

407

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  

International Nuclear Information System (INIS)

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-Oxfordiaonsidering 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)

408

Deformation microstructures  

DEFF Research Database (Denmark)

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 the order of 10 nm, produced by deformation under large sliding loads. Limits to the evolution of microstructural parameters during monotonic loading have been investigated based on a characterization by transmission electron microscopy. Such limits have been observed at an equivalent strain of about 10 for the misorientation angle and the density of high angle boundaries. However, the spacing between boundaries decreases with increasing strain without saturation even at extreme strains. The observed changes in microstructural parameters lead to a discussion of the flow stress/strain relationship.

Hansen, N.; Huang, X.

2004-01-01

409

Cyclic Plastic Deformation and Welding Simulation:  

OpenAIRE

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 ...

Ten Horn, C. H. L. J.

2003-01-01

410

Size effects on the magnetic properties of Cu-Nb nanofilamentary wires processed by severe plastic deformation  

International Nuclear Information System (INIS)

We report on the influence of the microstructure on the AC and DC magnetic properties of Cu-3.5% Nb nanofilamentary wires. Samples obtained from a single Cu-3.5% Nb wire were subsequently submitted to different plastic strain levels via drawing so that their microstructure was altered. Noticeable differences are observed in their isothermal DC magnetization curves that present a double-peak structure. The first peak, which occurs at low magnetic fields, is attributed to superconductivity induced in the Cu matrix due to the proximity effect. It is argued that the second peak is related exclusively to niobium. The dependence of these two distinct peaks on the characteristic nanometre length scales of the samples, i.e. dimension of the Nb filaments and interfilamentary spacing, are discussed

411

Effect of warm deformation on microstructure and mechanical properties of a layered and nanostructured 304 stainless steel  

Energy Technology Data Exchange (ETDEWEB)

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.

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

412

Effect of warm deformation on microstructure and mechanical properties of a layered and nanostructured 304 stainless steel  

International Nuclear Information System (INIS)

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

413

Consolidation state of incoming sediments to the Nankai Trough subduction zone: Implications for sediment deformation and properties  

Science.gov (United States)

hydromechanical properties of accreted and underthrust sediments are key parameters controlling the mechanics of earthquakes and the development of fluid pressure in subduction zones. We conducted consolidation tests on sediments from the Philippine Sea Plate (PSP) in the Nankai Trough to understand the consolidation state and hydraulic properties of the incoming sediment section before its incorporation into the subduction zone. We used mudstone and sandstone cores sampled from the Integrated Ocean Drilling Program Nankai Trough Seismogenic Zone Experiment at two reference sites (Site C0011 located on a basement low; and Site C0012 located on a basement high). Our experimental results indicate that most of the mudstone samples are normally consolidated or overconsolidated, with overconsolidation ratios (OCR) ranging from 0.89 to 2.52 at Site C0011 and 0.86 to 3.85 at Site C0012. Higher OCR values at Site C0012, at least at shallow depths, are likely caused by erosional unloading. This implies that Site C0011 may serve as a better geotechnical reference site. We also find that mudstones accreted along the frontal thrust are severely overconsolidated relative to coeval mudstones at Site C0011, which likely reflects enhanced consolidation due to increased horizontal tectonic stress. Sandstones in the incoming section on the PSP exhibit 2-3 orders of magnitude higher in situ permeability than the mudstones, and the siliciclastic sandstone we tested maintains a high permeability at stresses up to at least 70 MPa, suggesting that the sandstones may act as important pathways for drainage or pore pressure translation from depths of several kilometers.

Kitajima, Hiroko; Saffer, Demian M.

2014-07-01

414

The overall elastic dielectric properties of a suspension of spherical particles in rubber: An exact explicit solution in the small-deformation limit  

Science.gov (United States)

A solution is constructed for the homogenization problem of the elastic dielectric response of rubber filled with a random isotropic distribution of polydisperse spherical particles in the classical limit of small deformations and moderate electric fields. In this limit, the overall elastic dielectric response is characterized by five (two elastic, one dielectric, and two electrostrictive) effective constants. Explicit formulas are derived for these constants directly in terms of the corresponding constants describing the elastic dielectric response of the underlying rubber and the filler particles, as well as the concentration of particles. By means of comparisons with finite-element simulations, these formulas are shown to also be applicable to isotropic suspensions of monodisperse spherical particles, provided that the particle concentration is sufficiently away from percolation. With the aim of gaining physical insight into the extreme enhancement in electrostrictive properties displayed by emerging dielectric elastomer composites, specific results are examined for the case of suspensions wherein the rubber is incompressible and the particles are mechanically rigid and of infinite permittivity.

Lefèvre, Victor; Lopez-Pamies, Oscar

2014-10-01

415

An investigation of the effect of fatigue deformation on the residual mechanical properties of Ti-6Al-4V ELI  

Science.gov (United States)

Tensile properties, hardness, and Charpy impact toughness of Ti-6Al-4V extralow interstitial (ELI) with equiaxed ? and Widmanstätten ? structures at various stages of fatigue were investigated. Fatigue crack initiation characteristics of the same alloy were also investigated in this study. In the equiaxed ? structure, fatigue cracks initiated mainly at the interface between primary- ? grains, while in the Widmanstätten ? structure, they initiated across ? plates at an angle of around 45 deg to the stress axis. Specimens with the Widmanstätten ? structure fractured before adequate fatigue hardening was achieved because a multitude of microcracks readily formed. Specimens with the equiaxed ? structure fractured after adequate fatigue hardening developed. Tensile strength, 0.2 pct proof stress, and hardness increased clearly with increasing stress cycles and fatigue steps, particulary in the low-cycle fatigue (LCF) region, while impact toughness and elongation showed a reverse trend. It is suggested, therefore, that the dislocation density multiplies more rapidly near the specimen surface during the early stages of fatigue, while during the later stages of fatigue, dislocation density increases near the center of the specimen. Also, the dislocation multiplication will continue until saturation of the entire specimen has occurred.

Akahori, Toshikazu; Niinomi, Mitsuo; Fukunaga, Kei-Ichi

2000-08-01

416

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  

Energy Technology Data Exchange (ETDEWEB)

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)

Regle, H.

1994-12-31

417

Tangent lifting of deformations in mixed characteristic  

OpenAIRE

This article presents a new approach to the unobstructedness result for deformations of Calabi-Yau varieties by introducing the tangent lifting property for a functor on artinian local algebras. The verification that the deformation functor of a Calabi-Yau variety in characteristic 0 fulfills the tangent lifting property uses, just as the verification of the $T^1$-lifting property, the degeneration of the Hodge to de Rham spectral sequence. Our main use of our methods is how...

Ekedahl, Torsten; Shepherd-barron, Nick I.

2003-01-01

418

Deformation and weak decay of Lambda hypernuclei  

OpenAIRE

We use the self-consistent mean-field theory to discuss the ground state and decay properties of $\\Lambda$ hypernuclei. We first discuss the deformation of $\\Lambda$ hypernuclei using the relativistic mean-field (RMF) approach. We show that, although most of hypernuclei have a similar deformation parameter to the core nucleus, the shape of $^{28}$Si is drastically altered, from oblately deformed to spherical, if a $\\Lambda$ particle is added to this nucleus. We then discuss ...

Hagino, K.; Win, Myaing Thi; Nakagawa, Y.

2009-01-01

419

Effect of prestrain cold deformation and ?-particle irradiation on the high-temperature mechanical properties of 12Kh18N10T steel  

International Nuclear Information System (INIS)

The influence of preliminary cold deformation in the range of 5-70% on strength and plasticity of 12Kh18N10T steel irradiated by 50 MeV helium ion beam was studied. High-temperature tests were conducted at 1073K with 0.13 mmxmin-1 tension rate. It is shown that irradiation leads to sharp decrease of high-temperature ductility. Prior deformation may produce a positive effect only in the case of martensite ?'-phase formation in deformation range of 20-42%. Different effect of methods of irradiation on embrittlement is noted. High-temperature embrittlement is observed for all degrees of prior deformation during volume alloying by helium ions

420

Investigations of structure and properties in aluminium-magnesium alloys with high magnesium content subjected to different deformation and heat treatment  

International Nuclear Information System (INIS)

Structure of AMG11 alloys with beryllium, titanium, zirconium additions and a binary aluminium-11% magnezium alloy after different of deformation and heat treatments is investigated by electron-microscope. It is shown that application of the treatment combining deformation with succeeding slow heating up to the quenching temperature prevents #betta#-phase precipitation in the form of chains on the qrain boundaries as well as a decrease in plastic characteristics and resistance to stress corrosion during aging

421

G-factors in 210 Rn and octupole coupling of core excited states in 210Rn, 211Rn and 212Rn  

International Nuclear Information System (INIS)

The g-factors of isomeric states in 210Rn have been measured using the TDPAD technique. Semi-empirical shell model calculations, with explicit inclusion of the couplings to the 3- octupole vibration, are carried out for the core excited states in 210Rn and 211Rn, 212Rn. The resulting mixed multi-particle configurations are used to explain simultaneously the g-factors and enhanced E3 transitions which connect several pairs of these states

422

Emittance growth scaling laws for crossing systematic space-charge driven sixth-order resonances and random octupole driven fourth-order resonances in FFAGs  

International Nuclear Information System (INIS)

Scaling laws of the emittance growth factor (EGF) for a beam crossing the 6th order systematic space-charge resonances and the random 4th order resonance driven by octupoles are obtained by numerical multi-particle simulations. These scaling laws can be important in setting the minimum acceleration rate, and the maximum tolerable resonance strength for the design of the non-scaling fixed-field alternating gradient (FFAG) accelerators

423

Distributed actuator deformable mirror  

CERN Document Server

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.

Bonora, Stefano

2010-01-01

424

Deformed General Relativity  

OpenAIRE

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 ph...

Bojowald, Martin; Paily, George M.

2012-01-01

425

Developing a Virtual Rock Deformation Laboratory  

Science.gov (United States)

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

Zhu, W.; Ougier-simonin, A.; Lisabeth, H. P.; Banker, J. S.

2012-12-01

426

One-phonon octupole vibrational states in {sup 136}Xe, {sup 137}Cs, {sup 138}Ba, {sup 140}Ce and {sup 142}Nd with N = 82  

Energy Technology Data Exchange (ETDEWEB)

Excited high spin states in {sup 136}Xe, {sup 137}Cs, {sup 138}Ba, {sup 140}Ce and {sup 142}Nd with N = 82 are reorganized and interpreted in terms of the weak coupling mode of an octupole 3{sup -} phonon. Nearly identical sequences of levels with {Delta}I = 3 and {Delta}{pi} = yes built on 17/2{sup +} and 23/2{sup -} states are found, for the first time, up to 29/2{sup +} and 35/2{sup -}, respectively, for 22 states of {sup 137}Cs. Also, nearly identical sequences of levels with {Delta}I = 3 and {Delta}{pi} = yes built on the 6{sup +} and 9{sup -} states are found, for the first time, up to 14{sup +} and 17{sup -}, respectively, for 18 states of {sup 136}Xe, up to 14{sup +} and 17{sup -}, respectively, for 24 states of {sup 138}Ba and up to 11{sup +} and 14{sup -}, respectively, for 14 states of {sup 140}Ce. New spins and parities are assigned, tentatively, to the high spin states of these nuclei based on the weak coupling mode of an octupole 3{sup -} phonon. The weak coupling of an octupole 3{sup -} phonon needs to be considered when single particle configurations are assigned to high spin states. Neutron particle-hole states ({nu}h{sub 11/2} {sup -1} f{sub 7/2} {sup +1}) with weak coupling of an octupole 3{sup -} phonon are proposed, for the first time. The {nu}h{sub 11/2} {sup -1} f{sub 7/2} {sup +1} excitation energies (E{sub ext}(1p1h)) are nearly constant with increasing of Z. One-phonon excited states in {sup 136}Xe, {sup 137}Cs, {sup 138}Ba and {sup 140}Ce have the stretched weak coupling configurations of {Delta}I = 3. But one-phonon excited states in {sup 142}Nd show the non-stretched weak coupling configurations of an octupole phonon with {Delta}I = 3 and 2. (orig.)

Hwang, J.K.; Hamilton, J.H.; Ramayya, A.V. [Vanderbilt University, Physics Department, Nashville, TN (United States)

2013-10-15

427

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  

International Nuclear Information System (INIS)

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)

428

The effects of post annealing on the mechanical properties, microstructure and texture evolutions of pure copper deformed by twist extrusion process  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} Post annealing solve the softening problem occurred in repeated passes of TE. {yields} Post annealing decreased the coherent domain size of twist extruded sample. {yields} Post annealing increased the microstrain of twist extruded sample. {yields} Simple shear mode is the mechanism of deformation across the TE sample. {yields} The simple shear mechanism is disrupted by post annealing treatments. - Abstract: X-ray diffraction peak broadening analysis showed that performing a proper heat treatment between the twist extrusion passes of commercially pure copper decreased the coherent domain size and increased the microstrain. Moreover, SEM micrographs illustrated that annealed material contained new formed grains that could not grow due to lack of sufficient time. Under such circumstances, the ultimate strength was elevated about 45 MPa. The deformed material showed texture of simple shear deformation, changing by applying the post annealing.

Akbari Mousavi, S.A.A., E-mail: akbarimusavi@ut.ac.ir [School of Metallurgy and Materials Engineering, University College of Engineering, University of Tehran, North Kargar Street, P.O. Box: 11155-4563, Tehran (Iran, Islamic Republic of); Bahadori, Sh. Ranjbar [School of Metallurgy and Materials Engineering, University College of Engineering, University of Tehran, North Kargar Street, P.O. Box: 11155-4563, Tehran (Iran, Islamic Republic of)

2011-01-25

429

Plastic deformation effects on magnetic Barkhausen noise  

International Nuclear Information System (INIS)

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