Notizen: On a New Theory of the Magnetization Curve of Plastically Deformed Nickel Single Crystals

1970 ◽  
Vol 25 (11) ◽  
pp. 1747-1749
Author(s):  
H. Markert
Keyword(s):  
Single Crystals ◽  
Magnetization Curve ◽  
Domain Walls ◽  
Strain Curve ◽  
Domain Wall Motion ◽  
Experimental Results ◽  
Magnetization Process ◽  
Ir Radiation ◽  
Single Slip ◽  
The One

Abstract A new theory of the magnetization process in plastically deformed nickel single crystals of single slip orientation is outlined. It is based on the interaction between the (101)-180°-domain walls and the three types of primary edge dis-location dipole and multipole arrangements dominating in stage I, in the transition region and in stage II of the stress-strain curve, respectively, i.e. the [121]-dipole bundles, the rope-like clusters of such bundles extended along [121], and the [121] -multipole walls, all having [T01]-Burgers-vectors. In increasing magnetic fields the primary edge dislocation arrangements are shown to be capable to glide to new ob-stacles under the pressure of the (101) -180°-domain walls which will follow them and whose segments at the same time start to vault themselves cylindrically or pillow-shapedly be-tween these dislocation barricades, finally overcoming them at the coercive force by Barkhausen jumps. In an earlier paper 1 first experimental results had been reported concerning the large decrease of num-ber and size of Barkhausen jumps observed on samples of plastically deformed nickel and on magnetite dur-ing simultaneously superposed intensive ultrasonic ir-radiation. To explain this unexpected effect in terms of domain wall motion, an attempt had been made to mo-dify the usual potential theory of the magnetization curve by introducting a new hypothetical magnetization process which should enable the domain walls also to move to some extent irreversibly and continuously but without Barkhausen jumps. In the meantime, the mentioned problems were sub-ject of a recently published extensive dissertation 2 which contains, in addition to a more detailed descrip-tion of the experiments and of the apparatus used, also the analysis of the main consequences of these experi-mental facts with respect to the usual potential theories of the magnetization curve of deformed nickel, showing the strong inconsistency between these theories on the one hand and the experimental results, reported in 1 and 2 , and certain other important empirical facts on the other. Last not least this dissertation contains a new consistent quantitative theory of the magnetization curve of plastically deformed nickel single crystals of single slip orientation. The aim of this note is to summarize in a qualitative manner the main statements of that new theory. Its basic assumptions which could be proved by quoting numerous experimental facts as well as by detailed quantitative estimations are the following ones:

Cyclic Deformation of Al-Mg Single Crystals with a Single Slip Orientation

2007 ◽  
Vol 561-565 ◽  
pp. 2213-2216
Author(s):  
Toshiyuki Fujii ◽  
Shizuma Uju ◽  
Chihiro Watanabe ◽  
Susumu Onaka ◽  
Masaharu Kato
Keyword(s):  
Plastic Strain ◽  
Single Crystals ◽  
Strain Amplitude ◽  
Strain Curve ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Plastic Strain Amplitude ◽  
Solid Solution Hardening ◽  
Plateau Stress ◽  
Single Slip

Fully reversed tension-compression fatigue tests were performed on solid-solutioned Al-0.7mass%Mg single crystals with a single slip orientation under constant plastic-strain amplitudes. Dislocation microstructures were quantitatively examined by transmission electron microscopy. The cyclic stress–strain curve (CSSC) exhibited three distinct regions with a short plateau region in the intermediate plastic-strain amplitude range, and the plateau stress was 26MPa. Characteristic microstructures were developed corresponding to the three regions in the CSSC. Vein structure was observed at the low strain-amplitude region. In the plateau regime, the persistent slip bands (PSBs) were observed. Labyrinth structure was also observed at the higher strain-amplitude region. The plateau stress, the cyclic flow stress of PSBs, can be explained by considering not only the Orowan bowing stress and the dipole passing stress of screw dislocations but also solid-solution hardening by Mg atoms.

GENERATION AND PROPERTIES OF INFRARED RADIATION

2019 ◽  
Vol 6 (2) ◽  
pp. 101-137
Author(s):  
RUSTAM KHAKIMOVICH RAKHIMOV
Keyword(s):  
Electromagnetic Radiation ◽  
Infrared Radiation ◽  
Radiation Spectrum ◽  
Laws Of Nature ◽  
Primary Source ◽  
Ceramic Materials ◽  
Experimental Results ◽  
Ir Radiation ◽  
Scattering Of Light

The article presents the main basic laws of nature and modern theories of the nature of electromagnetic radiation, its generation, characteristics, and laws of reflection, absorption and scattering of light. The principle of transformation of the radiation spectrum of the primary source using the developed ceramic materials are shown, as well as experimental results of the interaction of IR radiation with matter and various mechanisms of influence on various objects and processes are described.

Numerical investigation of the propagation of shock waves in rigid porous materials: development of the computer code and comparison with experimental results

1996 ◽  
Vol 324 ◽  
pp. 163-179 ◽  
Author(s):  
A. Levy ◽  
G. Ben-Dor ◽  
S. Sorek
Keyword(s):  
Porous Materials ◽  
Initial Conditions ◽  
Computer Code ◽  
Experimental Results ◽  
Numerical Code ◽  
Materials Development ◽  
Numerical Predictions ◽  
Wide Range ◽  
Dimensional Version ◽  
The One

The governing equations of the flow field which is obtained when a thermoelastic rigid porous medium is struck head-one by a shock wave are developed using the multiphase approach. The one-dimensional version of these equations is solved numerically using a TVD-based numerical code. The numerical predictions are compared to experimental results and good to excellent agreements are obtained for different porous materials and a wide range of initial conditions.

Natural Vulcanization Accelerators in Hevea Latex

1948 ◽  
Vol 21 (4) ◽  
pp. 853-859
Author(s):  
R. F. A. Altman
Keyword(s):  
Amino Acids ◽  
Experimental Results ◽  
The Other ◽  
Active Nitrogen ◽  
Nitrogen Bases ◽  
Other Hand ◽  
Decomposition Processes ◽  
Volatile Products ◽  
Nitrogenous Substances ◽  
The One

Abstract As numerous investigators have shown, some of the nonrubber components of Hevea latex have a decided accelerating action on the process of vulcanization. A survey of the literature on this subject points to the validity of certain general facts. 1. Among the nonrubber components of latex which have been investigated, certain nitrogenous bases appear to be most important for accelerating the rate of vulcanization. 2. These nitrogen bases apparently occur partly naturally in fresh latex, and partly as the result of putrefaction, heating, and other decomposition processes. 3. The nitrogen bases naturally present in fresh latex at later stages have been identified by Altman to be trigonelline, stachhydrine, betonicine, choline, methylamine, trimethylamine, and ammonia. These bases are markedly active in vulcanization, as will be seen in the section on experimental results. 4. The nitrogenous substances formed by the decomposition processes have only partly been identified, on the one hand as tetra- and pentamethylene diamine and some amino acids, on the other hand as alkaloids, proline, diamino acids, etc. 5. It has been generally accepted that these nitrogenous substances are derived from the proteins of the latex. 6. Decomposition appears to be connected with the formation of a considerable amount of acids. 7. The production of volatile nitrogen bases as a rule accompanies the decomposition processes. These volatile products have not been identified. 8. The active nitrogen bases, either already formed or derived from complex nitrogenous substances, seem to be soluble in water but only slightly soluble in acetone.

The yield strength anomaly of single-slip-oriented Fe–Al single crystals

2007 ◽  
Vol 15 (2) ◽  
pp. 103-107 ◽  
Author(s):  
D. Wu ◽  
I. Baker ◽  
P.R. Munroe ◽  
E.P. George
Keyword(s):  
Yield Strength ◽  
Single Crystals ◽  
Single Slip

Definition of the yield point in plasticity and its effect on the shape of the yield locus

1966 ◽  
Vol 1 (4) ◽  
pp. 331-338 ◽  
Author(s):  
T C Hsu
Keyword(s):  
Yield Point ◽  
Experimental Work ◽  
Strain Curve ◽  
Yield Locus ◽  
Experimental Results ◽  
Stress Strain Curve ◽  
Proportional Limit ◽  
Stress Strain ◽  
Small Section ◽  
Definition Of

Three different definitions of the yield point have been used in experimental work on the yield locus: proportional limit, proof strain and the ‘yield point’ by backward extrapolation. The theoretical implications of the ‘yield point’ by backward extrapolation are examined in an analysis of the loading and re-loading stress paths. It is shown, in connection with experimental results by Miastkowski and Szczepinski, that the proportional limit found by inspection is in fact a point located by backward extrapolation based on a small section of the stress-strain curve, near the elastic portion of the curve. The effect of different definitions of the yield point on the shape of the yield locus and some considerations for the choice between them are discussed.

Wechselwirkungen in Molekülkristallen, 162 [1, 2]. Di(arylsulfonyl)amine – geeignete Liganden für lipophil umhüllte Polyionen-Aggregate mit Cs⊕ -Schichten variabler Dicke / Interaction in Molecular Crystals, 162 [1, 2]. Di(arylsulfonyl)amines – Ligands for Lipophilically Wrapped Polyion Aggregates with Cs⊕ -Layers of Variable Thickness

2000 ◽  
Vol 55 (11) ◽  
pp. 1053-1066 ◽  
Author(s):  
Hans Bock ◽  
Erik Heigel
Keyword(s):  
Single Crystals ◽  
Alkali Salt ◽  
Amide Ligands ◽  
High Coordination Number ◽  
Anionic Ligands ◽  
Structure Determinations ◽  
Phenyl Rings ◽  
Structural Database ◽  
The One ◽  
High Coordination

Di(arylsulfonyl)amides are presented as novel anionic ligands for polycation aggregates. Starting from the structures of Ag⊕ and Na⊕ salts registered in the Cambridge Structural Database, the largest alkali cation Cs⊕ with high coordination number has been selected and in extreme low gradient crystallisation single crystals of both cesium-di(benzenesulfonyl)amide and cesium-di(4-toluenesulfonyl)amide were grown. Their structure determinations revealed that both polymeric salts contain cation layers (Cs⊕)∝: The one lipophilically wrapped by di(benzenesulfonyl)amide ligands exhibits hexagonal (Cs⊕)6 subunits, whereas the methylsubstituted di(4-toluenesulfonyl)amide ligands of the other one are interspersed within (Cs⊕)^ layers. The resulting lipophilically wrapped sheets with Cs⊕ cations of ten- and twelve-fold coordination to disulfonyl O and C centers vary in their overall thickness of 1.77 nm and 1.39 nm because the toluene substituents in the thinner one are tilted. The remarkable effects caused by the 4-methyl substitution of the phenyl rings determine the structures of the parent di(arylsulfonyl)amines as well: Contrary to the polymeric phenyl substituted derivative, the toluene homologue crystallizes in dimers. The single crystals grown of the closely related di(arylsulfonyl)amides with or without para methyl substituents and their poly(Cs⊕) aggregates without any solvent inclusion show hitherto unknown structural motifs and, therefore, further improve our knowledge of alkali salt self-organisation phenomena in crystals.

The Use of Strain Energy and Fracture Correlation to Determine Life Expectancy for Notched Components

2009 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
Charles Cross ◽  
M.-H. Herman Shen
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Cross Section ◽  
Strain Energy ◽  
Notch Root ◽  
Stress Gradient ◽  
Strain Curve ◽  
Experimental Results ◽  
Cyclic Process ◽  
Notched Components

An energy-based method for predicting fatigue life of half-circle notched specimens, based on the nominal applied stress amplitude, has been developed. This developed method is based on the understanding that the total strain energy dissipated during a monotonic fracture and a cyclic process is the same material property, where the density of each can be determined by measuring the area underneath the monotonic true stress-strain curve and measuring the sum of the area within each Hysteresis loop in the cyclic process, respectively. Using this understanding, the criterion for determining fatigue life prediction of half-circle notched components is constructed by incorporating the stress gradient effect through the notch root cross-section. Though fatigue at a notch root is a local phenomenon, evaluation of the stress gradient through the notch root cross-section is essential for incorporating this method into finite element analysis minimum potential energy process. The validation of this method was carried out by comparison with both notched and unnnotched experimental fatigue life of Aluminum 6061-T6 (Al 6061-T6) specimens under tension/compression loading at the theoretical notch fatigue stress concentration factor of 1.75. The comparison initially showed a slight deviation between prediction and experimental results. This led to the analysis of strain energy density per cycle up to failure, and an improved Hysteresis representation for the energy-based prediction analysis. With the newly developed Hysteresis representation, the energy-based prediction comparison shows encouraging agreement with unnotched experimental results and a theoretical notch stress concentration value.

Peierls “Washboard” Controls Dynamics of the Domain Walls in Molecular Ferrimagnets

2015 ◽  
Vol 233-234 ◽  
pp. 55-59
Author(s):  
Marina Kirman ◽  
Artem Talantsev ◽  
Roman Morgunov
Keyword(s):  
Domain Wall ◽  
Crystal Lattice ◽  
Domain Walls ◽  
Low Frequency ◽  
Domain Wall Motion ◽  
Lattice Parameter ◽  
Structural Defects ◽  
Crystal Lattice Parameter ◽  
Wall Width ◽  
Debye Relaxation

The magnetization dynamics of metal-organic crystals has been studied in low frequency AC magnetic field. Four modes of domain wall motion (Debye relaxation, creep, slide and over - barrier motion (switching)) were distinguished in [MnII(H(R/S)-pn)(H2O)] [MnIII(CN)6]⋅2H2O crystals. Debye relaxation and creep of the domain walls are sensitive to Peierls relief configuration controlled by crystal lattice chirality. Structural defects and periodical Peierls potential compete in the damping of the domain walls. Driving factor of this competition is ratio of the domain wall width to the crystal lattice parameter.

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