摘要:

The room temperature-internal friction of single crystals of NaCl vibrating at a frequency of 90 kc/s has been measured at strain amplitudes up to 2.7 × 10−4. The damping of plastically deformed crystals increased with increasing strain amplitude, and can be attributed to the motion of the dislocations introduced by the deformation. Vibration of specimens at high amplitudes changed their internal friction in three distinct ways.

ISSN:0031-8086    

DOI:10.1080/14786436008238294

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The reverse bending of single crystal bars of silver chloride that have already been singly bent has been studied by using the photoelmtic effect. There is no indication of the preferential deformation at a certain place on the bar found when annealed crystals are bent. This is also true if the crystals are first heated at temperatures between room temperature and 375[ddot]c, but if they are heated at higher temperatures and at a result all detectable long range stresses are removed from the crystal the sharp yield point of the first bending is recovered. The result. are considered in terms of a simple dislocation model.

ISSN:0031-8086    

DOI:10.1080/14786436008238295

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

A method for preparing chemically sensitizod, dislocation-free, silver bromide single crystals is described in this paper. When these crystals are strained beyond the elastic limit and exposed to light, both the dislocation loops which are generated at the surfaces, and the surface terraces which may be associated with them, are made visible by the separation of particles of silver. The glide planes of the dislocations may then be determined from microscopic measurements and the Burgers vectors of the dislocations may be inforred, if the stress distribution responsible for the deformation is at least qualitatively known. This provides a powerful method for studying dislocation interactions and the fundamental processes of plastic deformation.

ISSN:0031-8086    

DOI:10.1080/14786436008238296

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The electrical resistance of two iron-aluminium alloys, bordering on the composition Fe2A1, was measured at room and liquid nitrogen temperatures after inducing various states of order. By means of an analysis based on values of residual resistivity and of the temperature coefficient of resistivity, the influence of order on electronic factors in the conductivity, and on the perturbation of the lattice that produce scattering, were separately estimated. The freedom of conduction electrons diminishes as the order increases, and the decrease in low temperature resistivity associated with increasing order is due to the greatly reduced scattering potential. Those conclusions permitted a qualitative interpretation of the form of the anomalous resistance/temperature relation at high temperatures.

ISSN:0031-8086    

DOI:10.1080/14786436008238297

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

The Knight shift and line-width of the7Li resonance in dilute Li-Mg alloys has been investigated. The observed rapid fall in Knight shift with alloying concentration is interpreted using Drain's theory. Line width measurements show that the activation energy of self-diffusion of the7Li atoms increases from 13.1±0.2 kcal/mole for pure lithium to 14.5 ±0.3 kcal/mole for the 10 at. % magnesium alloy.

ISSN:0031-8086    

DOI:10.1080/14786436008238298

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Crystals of cadmium were grown from the vapour on a quartz fibre in an argon diffusion cell designed so that the temperature,T, could be measured and the supersaturation, σ, calculated at every point. A critical σ of ∼ 0 4 for nucleation was observed below which no crystals grew and above which the density of crystals increased with σ For ≲σ2, crystals grew as whiskers and thin platelets independently of σ andT; for 2≲σ≲102the end products were thick hexagonal plates; for σ≳102andT≲250°c spike and leaf dendrites appeared and grew to large dimensions. The observed dependence of whisker growth rates on σ and whisker radius showed that growth was probably controlled by the diffusion of cadmium vapour through argon. Evidence for both tip growth and non-tip growth of whiskers is presented.

ISSN:0031-8086    

DOI:10.1080/14786436008238299

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

Distribution and densities of dislocations, determined by electron transmission microscopy, flow stress and stored energy measurements (by microcalorimetry) on cold-worked polycrystalline silver are correlated with each other, The dislocations are arranged in dense networks forming the boundaries of an otherwise relatively dislocation-free cell structure. The flow stress is explained quantitatively in terms of the forest intersection mechanism at the boundaries. The stored energy after recovery is of the same order as the total self-energy of the dislocation arrangement, so that the long-range stresses must be largely relaxed. The considerable energy release during the recovery stage produces no observable change in dislocation distribution. This recovery stage is thought to be due to the relief of long-range stresses or to the removal of point defects.

ISSN:0031-8086    

DOI:10.1080/14786436008238300

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

X-ray diffraction patterns from bulk specimens of nickel deformed by compression have been measured with a Geiger-counter spectrometer. A composite specimen has been used to overcome the effects of preferred orientations.

ISSN:0031-8086    

DOI:10.1080/14786436008238301

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

摘要:

A new calculation is made of the stored energy in a deformoed isotropic material, in terms of the mean-square lattice strain. An isotropic stress distribution is assumed.

ISSN:0031-8086    

DOI:10.1080/14786436008238302

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor

ISSN:0031-8086    

DOI:10.1080/14786436008238303

出版商:Taylor & Francis Group    

年代:1960

数据来源: Taylor