Royal Society

About: Royal Society is a nonprofit organization based out in London, United Kingdom. It is known for research contribution in the topics: Ion & Population. The organization has 886 authors who have published 1820 publications receiving 44073 citations. The organization is also known as: The Royal Society of London for Improving Natural Knowledge & Royal Society of London.

The mean free path of electrons in metals

Abstract: (2001). The mean free path of electrons in metals. Advances in Physics: Vol. 50, No. 6, pp. 499-537.

The formation of emulsions in definable fields of flow

Abstract: The physical and chemical condition of emulsions of two fluids which do not mix has been the subject of many studies, but very little seems to be known about the mechanics of the stirring processes which are used in making them. The conditions which govern the breaking up of a jet of one fluid projected into another have been studied by Rayleigh and others, but most of these studies have been concerned with the effect of surface tension or dynamical forces in making a cylindrical thread unstable so that it breaks into drops. The mode of formation of the cylindrical thread has not been discussed. As a rule in experimental work it has been formed by projecting one liquid into the other under pressure through a hole. It seems that studies of this kind which neglect the disruptive effect of the viscous drag of one fluid on the other, though interesting in themselves, tell us very little about the manner in which two liquids can be stirred together to form an emulsion. When one liquid is at rest in another liquid of the same density it assumes the form of a spherical drop. Any movement of the out er fluid (apart from pure rotation or translation) will distort the drop owing to the dynamical and viscous forces which then act on its surface. Surface tension, however, will tend to keep the drop spherical. When the drop is very small, or the liquid very viscous, the stresses due to inertia will be small compared with those due to viscosity.

The Mechanism of Plastic Deformation of Crystals. Part I. Theoretical

Abstract: Experiments on the plastic deformation of single crystals, of metals and of rock salt have given results which differ in detail but possess certain common characteristics. In general the deformation of a single crystal in tension or compression consists of shear strain in which sheets of the crystal parallel to a crystal plane slip over one another, the direction of motion being some simple crystal-lographic axis. The measure of this strain, which will be represented by s , is the ration of the relative lateral movement of two parallel planes of slip to the distance between them. Thus it is defined in the same way as the shear strain considered in the theory of elasticity.

Dislocations in a simple cubic lattice

Abstract: The properties of dislocations are calculated by an approximate method due to Peierls. The width of a dislocation is small, displacements comparable with the interatomic distance being confined to a few atoms. The shear stress required to move a dislocation in an otherwise perfect lattice is of the order of a thousandth of the theoretical shear strength. The energy and effective mass of a single dislocation increase logarithmically with the size of the specimen. A pair of dislocations of opposite sign in the same glide plane cannot be in stable equilibrium unless they are separated by a distance of the order of 10 000 lattice spacings. If an external shear stress is applied there is a critical separation of the pair of dislocations at which they are in unstable equilibrium. The energy of this unstable state is the activation energy for the formation of a pair of dislocations. It depends on the external shear, and for practical stresses is of the order of 7 electron volts per atomic plane. The size and energy of dislocations in real crystals are unlikely to differ greatly from those calculated: the stress required to move a dislocation and the critical separation of two dislocations may be seriously in error.

The Latent Energy Remaining in a Metal after Cold Working

Abstract: Measurements of the latent energy remaining in metal rods after severe twisting are described. Very much more cold work can be done on a metal in torsion than in direct tension. It is found that as the total amount of cold work which has been done on a specimen increases the proportion which is absorbed decreases. Though saturation was not fully reached even with twisted rods, curves representing the experimental results for copper indicate that it would have been reached at a plastic strain very little greater than the strain at fracture. The amount of cold work necessary to saturate copper with latent energy at 15° C. is thus found to be slightly greater than 14 calories per gram. By using compression instead of torsion, it was found possible to do much more cold work on copper than this, and compression tests revealed the fact that the compressive stress increases with increasing strain till the total applied cold work was equivalent to 15 calories per gram. No further rise in compressive stress occurred with further compression even though the specimen was compressed till its height was only 1/53rd of its original height.