摘要:

In general, the analysis of dislocations in anisotropic media can only be carried out numerically. For a dislocation which is either parallel to an axis of rotational symmetry or normal to an axis of even-fold rotational symmetry, however, an analytic solution for the stress field of the dislocation can be obtained. The stress field of any dislocation in a hexagonal crystal can be determined analytically.

ISSN:0031-8086    

DOI:10.1080/14786436808227510

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Sondheimer oscillations in the electrical resistivity have been measured in aluminium single crystals. The direction of the magnetic field was in the sector between the ⟨100⟩ and the ⟨110⟩ directions, and it is shown that in this case the oscillations may be interpreted as type 2 according to the Gurevich theory.

ISSN:0031-8086    

DOI:10.1080/14786436808227511

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A simple prescription is given for calculating densities of states in arbitrary monovalent alloys maintained at fairly arbitrary volumes. In the cases of the pure metals, where comparison with experiment and other theoretical work is possible, satisfactory results are obtained for interpretation of the soft x-ray emission spectra and the Fermi level effective masses.

ISSN:0031-8086    

DOI:10.1080/14786436808227512

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The yield stress data of irradiated Ferrovac iron are shown to be closely approximated by the expression Δ[sgrave]=A[1—exp (—Bφt)]1/2with a saturation exposure of 2 × 1019nvt (E> 1·45 MeV). The maximum increment in the yield stress is 25 000 p.s.i. and the volume of the defect calculated fromBis 4·4 × 10−19cm3. If the defect is considered a spherical depleted zone this corresponds to a diameter of 95 Å and the actual defect is probably near 50 Å in diameter at saturation. Deviations at low exposures are explained on the basis of enhanced carbide precipitation. The mode of zone production and growth is believed dependent on the amount of available (mobile) carbon.

ISSN:0031-8086    

DOI:10.1080/14786436808227513

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The absolute thermoelectric power of the liquid system copper-tin has been investigated as a function of temperature and composition. A detailed comparison between the Ziman theory of electron transport and the experimental data is possible for this particular system because the three partial structure factors are reasonably well established. The comparison shows that the prominent features in the observed data can be readily understood in terms of the basic theory.

ISSN:0031-8086    

DOI:10.1080/14786436808227514

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Tetragonal crystalline solutions in the system TiO2–SnO2were annealed at 850°C and 1000°C to study the mechanism of separation within the exsolution dome. X-ray diffraction results indicated a unidirectional composition variation along [001]. The formation of the modulated structure was verified by electron microscopy, which showed alternately dark and light lamellae composed of SnO2-rich and TiO2-rich plates perpendicular to [001]. The sum of the thicknesses of the dark and light lamellae (‘wavelength') decreased in the early stages of the separation and then increased at longer annealing times, the thickness varying between 180 and 400 Å. It is proposed that the precipitation proceeds as follows: crystalline solution→intermediate modulated phase → equilibrium phases. The first step shows all the characteritics of the spinodal type of mechanism. It is shown theoretically that a one-directional fluctuation of composition parallel to [001] can be expected in the system TiO2-SnO2.

ISSN:0031-8086    

DOI:10.1080/14786436808227515

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Stacking faults were observed in CdS crystals into which Hg had been diffused. Type II faults predominated over Type III faults, and no Type I faults were observed. A model, based on the effective charges present on the Cd and Hg ions, is presented, which indicates that the presence of Hg in the lattice lowers the stacking-fault energy.

ISSN:0031-8086    

DOI:10.1080/14786436808227516

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The martensite transformation which occurs either thermally or by plastic deformation in the equi-atomic Ni-Ti alloy has been studied in detail by transmission electron microscopy. The transformation occurs by alternate simple shears on {112} planes and in ⟨111⟩ directions of the parent B2 structure. These shears convert the original lattice into two distinct close-packed monoclinic martensites which may be described as distorted hexagonal close-packed structures if atom types are not considered. In this manner the deformation associated with the transformation is almost perfectly compensated without the introduction of any additional defect. The movement of the atoms involved in this transformation has been determined, in turn accounting for the remarkable memory effect associated with this material.

ISSN:0031-8086    

DOI:10.1080/14786436808227517

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The width of a static edge dislocation calculated with the usual sinusoidal force law does not differ greatly from the width calculated with the force law proposed by Nabarro. The situation is quite different when the dislocation moves at a fast subsonic velocity or at a transonic velocity. Because of the large divergence in the results it is concluded that the nature of the solution to the problem of a dislocation moving at a high speed in a crystal lattice remains uncertain.

ISSN:0031-8086    

DOI:10.1080/14786436808227518

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A first principles pseudopotential calculation of metallic binding is performed via an ansatz previously used successfully in discussing electron transport properties. Without recourse to any experimental data (other than the values of the fundamental constants) a single procedure is found to give energy-volume curves for all eight monovalent metals which are consistent with the observed cohesive energies, lattice parameters and pressure-volume relationships. Though not as accurate as conventional cellular methods, it has the merit of revealing how the electron-ion scattering variations which give the monovalent metals their distinctive transport properties are also responsible, in large measure, for the individual characteristics, from metal to metal, associated with cohesion.

ISSN:0031-8086    

DOI:10.1080/14786436808227519

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor