Stress-generated prismatic dislocation loops in quenched copper
TL;DR: In this paper, a number of prismatic dislocation loops have been observed in thin films obtained from copper foils which have been water quenched from 1055°C. The spacing of the loops is consistent with the theory of Bullough and Newman, which enables a value of the critical resolved shear stress to be estimated.
About: This article is published in Acta Metallurgica.The article was published on 1963-04-01. It has received 49 citations till now. The article focuses on the topics: Critical resolved shear stress & Slip (materials science).
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TL;DR: In this article, a new theory of work hardening in dispersion-hardened single crystals is described, which is based on the fact that, if the particles do not deform plastically, and the interface between particle and matrix does not fracture, then secondary slip must occur locally round each particle when the crystal is deformed, even though the crystal may appear to deform by single slip.
Abstract: A new theory of work hardening in dispersion-hardened single crystals—by which we mean soft crystals containing hard non-deforming particles of a second phase—is described. It is based on the fact that, if the particles do not deform plastically, and the interface between particle and matrix does not fracture, then secondary slip must occur locally round each particle when the crystal is deformed, even though the crystal may appear to deform by ‘single slip’. The density of secondary dislocations rises steeply with strain, and acts as a forest impeding the movement of primary glide dislocations. The theory predicts a relation between stress and strain (eqn. (9)) which is in good agreement with experimental results. Fracture of the particle-matrix interface, and the importance of the strength of this interface, are discussed.
528 citations
TL;DR: In this article, the displacement damage through heavy ion irradiation was studied on two tungsten grades (coarse grained Tungsten (CGW) and nanocrystalline and ultrafine grained (NCW) using different displacement per atom rates and different irradiation temperatures (RT and 1050 K).
78 citations
Cites background from "Stress-generated prismatic dislocat..."
...10 shows an interesting phenomena, dislocation loop rafting, that was observed in various BCC metals under neutron and heavy ion irradiation (both thin foils and bulk) [8,48,54,89,90]....
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TL;DR: In this paper, the influence of concurrent phase transformation on the deformation of Armco iron and electrolytic vacuum cast (EVC) iron was studied under compressive and torsional stresses from 200 to 1085 psi.
66 citations
TL;DR: In this article, it was shown that the annealing behavior of copper quenched from high temperature is similar to that of silver, provided that care is taken in both cases to avoid contamination by oxygen.
Abstract: It is shown, using electrical resistance measurements and transmission electron microscopy, that the annealing behaviour of copper quenched from high temperature is similar to that of silver, provided that care is taken in both cases to avoid contamination by oxygen. To achieve this, copper was quenched from an atmosphere of carbon monoxide. The results obtained under these conditions suggest that the divacancy is the principal defect retained in copper after quenching from high temperatures. The temperatures at which stacking-fault tetrahedra anneal out in silver and gold were studied by transmission microscopy. In silver, tetrahedra are stable up to at least 930°c. The stability of tetrahedra in gold depends on their size, being greater the larger the tetrahedra. Finally it has been shown that dislocation loops, not tetrahedra, predominate as the clustered vacancy defect in gold if, after quenching from high temperature to 0°c, the gold is rapidly upquenched to 100°c.
60 citations
TL;DR: In this article, the long-range elastic interactions between dislocations and loops, both prismatic and shear, have been calculated for an isotropic medium, from the energy of interaction.
Abstract: The long-range elastic interactions between dislocations and loops, both prismatic and shear, have been calculated for an isotropic medium. From the energy of interaction the magnitude and directio...
52 citations
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15 Mar 2007
TL;DR: The first serious application of the microscope to the study of metallic structure was made in 1864 by Dr. H. Sorby, of Sheffield, but the lead then given was not followed for nearly a quarter of a century as mentioned in this paper.
Abstract: THE subject of the lecture was the structure of metals, mainly as revealed by the microscope. The first serious application of the microscope to the study of metallic structure was made in 1864 by Dr. H. Sorby, of Sheffield, but the lead then given was not followed for nearly a quarter of a century. In the last fifteen years or so, however, it had been taken up with the greatest zeal and success, nowhere more than in Dr. Sorby's own town. There and elsewhere, in France, Germany, and America, as well as at home, a band of enthusiastic workers had been engaged in creating what might be described as a novel branch of physical science, as interesting on the physical side as it was important in its practical aspect. In this work Cambridge had done its share. The lecturer referred especially to work done in the engineering laboratory by Rosenhain, Humfrey, and other of his own former research students, and to the admirable investigation of alloys carried out by Neville and Heycock in the laboratory of Sidney Sussex College.
2,399 citations
TL;DR: In this paper, a kinematical theory of electron microscope images of dislocations observed by transmission in thin crystalline foils is presented, showing that the contrast is essentially phase contrast in the Bragg diffracted beams, the phase differences being due to the displacements of the atoms from their positions in the ideally perfect crystal.
Abstract: This paper describes a kinematical theory of electron microscope images of dislocations observed by transmission in thin crystalline foils. The contrast is essentially phase contrast in the Bragg diffracted beams, the phase differences being due to the displacements of the atoms from their positions in the ideally perfect crystal. The theory explains many of the characteristic features of the observed images, such as the dependence of the contrast on orientation, the reversal of contrast on bright and dark field images, the fact that dislocations are generally dark on bright field images, the position and width of the images, the general nature of the profile, the occurrence of dotted dislocations, the invisibility of some dislocations, the dependence of contrast on the inclination of the dislocation, and the occurrence of double images. The theory also accounts satisfactorily for the nature and width of the dislocation images obtained with X-rays.
380 citations
TL;DR: In this paper, the authors described the properties of prismatio and concentric helical prismatic dislocations generated by the stress field which appears around a spherical glass inclusion in a silver chloride crystal when the crystal is cooled from a temperature of 370°c to room temperature.
Abstract: Prismatio and concentric helical prismatic dislocations are generated by the stress field which appears around a spherical glass inclusion in a silver chloride crystal when the crystal is cooled from a temperature of 370°c to room temperature. The properties of these dislocations are described and their origin is discussed.
358 citations
TL;DR: A large increase in the critical shear stress of high-purity aluminium single crystals can be achieved by water quenching, instead of furnace cooling, after annealing at a high temperature as mentioned in this paper.
Abstract: Summary A large increase in the critical shear stress of high-purity aluminium single crystals can be achieved by water quenching, instead of furnace cooling, after annealing at a high temperature. This quench-hardening effect is insensitive to purity and is present in crystals of zone-refined aluminium. It increases rapidly with increase in the quenching temperature. The fully hardened state is reached, not instantly upon quenching, but only after ageing at room temperature. Various observations suggest that while quenching strains may be partly responsible for the hardening they cannot account for the whole effect, and that quenched-in vacancies also make an important contribution.
100 citations
73 citations