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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 292-299 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The coincidence-site-lattice theory of grain boundaries has been applied to simple two-phase boundaries. Symmetric and unsymmetric tilt boundaries, pure twist boundaries and unrotated and untwisted boundaries have all been considered. It has been shown that each type of boundary can be described in terms of a characteristic coincidence-site lattice. In addition, the dislocation content within the interphase boundaries has been defined in terms of Burgers circuits described with respect to the original crystal lattices in the new coincidence-site lattices.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 31 (1975), S. 280-292 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The concepts embodied in the coincidence-site-lattice theory of grain boundaries are shown to be compatible with a large number of tensor quantities which have their origin in the continuum field theory of dislocations. More specifically such tensor quantities as distortion, grain-boundary dislocation density, and incompatibility have all been developed in terms of a general grain boundary for a continuum as well as for the discrete crystal. A generalized Burgers circuit about an arbitrary grain boundary is also shown to be a natural outcome of the present development.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 33 (1977), S. 480-486 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Coherent as well as incoherent interfaces associated with simple two-phase boundaries have been analyzed in terms of the concepts of differential geometry. Such tensor quantities as distortion, torsion and curvature have been developed and are all shown to give significant insight in describing the Burgers circuits and dislocation content of such boundaries.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 33 (1977), S. 865-872 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A differential geometric analysis has been made of the various tensor quantities associated with a grain boundary. It is shown how these tensor quantities can be developed so as to give a unique and generalized formulation for the description of the dislocation content of such boundaries.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 8 (1973), S. 143-145 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 8 (1973), S. 839-847 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A detailed numerical analysis has been made of the passing of superlattice dislocations in the presence of frictional forces and the results compared with those for ordinary dislocations. In particular, it was shown that the behaviour of superlattice dislocations is similar to that of ordinary dislocations, only at very high frictional stresses or at very low vertical separations. It was also shown that dipole strength can be increased significantly by decreasingy, the vertical separation, untily reaches a critical value,y c, when the cross-slip forces due to the internal stresses are sufficient to induce non-thermal cross-slip thus annihilating the passing dislocations. Edge dislocations, on the other hand, cannot annihilate themselves by climb, and hence, smaller vertical separation can be obtained increasing the dipole strength significantly. The effect of thermal and nonthermal cross-slip on the work-hardening of ordered alloys is discussed in detail. For the purpose of illustration, the calculations were made for FeCo. The results, however, are quite general and are applicable to all B2-structure alloys.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 9 (1974), S. 29-40 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A unified dislocation theory of grain boundaries proposed earlier for simple cubic crystals has been extended to include the case of ordered and disordered body-centred-cubic structures. Pure symmetric and asymmetric tilt and pure twist boundaries have been treated in detail and extended to an arbitrary grain boundary. It is shown that a unique set of coincidence site lattices exists for both the symmetric and asymmetric boundaries and that each of these sets, in turn, depends upon the rotation axis which characterizes the boundary. Furthermore, a unique set of grain-boundary dislocations is associated with each of these coincidence site lattices. The results are then applied to the transmission electron microscopy studies carried out in Part 2 of the present study.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 14 (1979), S. 1717-1732 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Any surface, in order to decrease its surface energy, contracts. It is shown for the first time that this contraction is formally equivalent to the introduction of a continuous distribution of surface dislocations. Equilibrium is attained when the increase in strain energy associated with these surface dislocations just balances the corresponding decrease due to the reduction in free surface area. Numerical calculations have been carried out for finite solid and liquid bodies as well as for liquid droplets in contact with solids. These findings suggest that it is possible to reformulate the behaviour of liquids in terms of dislocation theory in a much more general way than has hitherto been done.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 10 (1974), S. 181-200 
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé On a pu montrer que les fissures de surface, aussi bien que les cavités peuvent être représentés par des dislocations de surface. Celles-ci ont pour rôle d'empêcher que des efforts de traction n'agissent sur une surface libre se trouvant dans un corps sous contraintes. A l'aide des techniques numériques, on montre qu'il est possible de déterminer l'énergie et le champ de contrainte qui sont associés à des fissures ou à des cavités. Dès lors, en principe, tout problème de cavité ou de fissure peut être solutionné à quelque degré d'approximation que ce soit en utilisant la formulation en termes de dislocations qui est décrite dans l'article.
    Abstract: Zusammenfassung Man zeigt daß Oberflächenrisse sowohl als Löcher in Form von Oberflächendislokationen dargestellt werden können. Diese Oberflächendislokationen bestehen um zu versichern daß an keiner freien Oberfläche eines Körpers unter Spannung, Zugkräfte bestehen. Mittels numerischen Verfahren wird gezeigt daß die Energie sowohl als das durch Risse oder Löcher bedingte Spannungsfeld bestimmt werden können. So kann man dann grundsätzlich irgend ein Loch- oder Rißproblem mit jeglichem Annäherungsgrad lösen indem man das in diesem Bericht beschriebene Dislokationsverfahren anwendet.
    Notes: Abstract It has been shown that surface cracks as well as holes can be represented in terms of surface dislocations. These surface dislocations exist in order to insure that no tractions act on any free surface within a stressed body. Using numerical techniques, it is shown that the energy as well as the stress field associated with cracks or holes can be determined. In principle then, any hole or crack problem can be solved to any degree of approximation using the dislocation formulation described herein.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 14 (1978), S. 155-171 
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé La représentation d'une fissure par des dislocation discrètes et d'un trou par des dislocations de surface est utilisée pour l'étude de l'interaction entre une fissure résultant d'un état de tension et un trou. On montre que pour une dimension et une forme données d'un trou préexistant dans un matériau homogène il ne peut exister une fissure que d'une seule dimension pour maintenir l'équilibre. Cette dimension d'équilibre de la fissure dépend de la dimension et de la forme du trou ainsi que de la distance entre la fissure et le trou. Toutes les fissures dont les dimensions sont supérieures ou inférieures à la dimension d'équilibre sont instables. L'effet de la dimension de la forme du trou sur la dimension d'équilibre de la fissure est illustré. L'assymétrie de la configuration des dislocations associée à la fissure et au trou est utile pour comprendre la concentration de contrainte qui existe au voisinage de l'extrémité d'une fissure et au bord d'un trou, ainsi que pour étudier d'une manière plus approfondie le mécanisme de croissance de la fissure et du trou.
    Notes: Abstract The representation of a crack by discrete dislocations and that of a hole by surface dislocations is used to study the interaction between a tensile crack and a hole. It is shown that for a given size and shape of a pre-existing hole in a homogeneous material, a crack of only one size can exist in equilibrium. This equilibrium size of the crack depends on the size and shape of the hole and also on the distance between the crack and the hole. All cracks whose size is greater than or lesser than the equilibrium size are unstable. The effect of the size and shape of the hole on the equilibrium size of the crack is illustrated. The asymmetry in the dislocation configuration of the crack and the hole is useful in understanding the stress concentration that exists around the crack tip and the corners of the hole and to further study the mechanism of the growth of the crack and the hole.
    Type of Medium: Electronic Resource
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