Showing papers in "Canadian Journal of Physics in 1967"
TL;DR: Phenomenological equations between dislocation velocity, effective shear stress, temperature, and pressure are presented in this article, where it is suggested that the term "activation volume" be properly assigned to t...
Abstract: Phenomenological equations between dislocation velocity, effective shear stress, temperature, and pressure are presented. It is suggested that the term "activation volume" be properly assigned to t...
317 citations
TL;DR: A computer program that determines the stress required to move a dislocation through an array of obstacles distributed at random on a slip plane has been written as discussed by the authors, which has been used to meas...
Abstract: A computer program that determines the stress required to move a dislocation through an array of obstacles distributed at random on a slip plane has been written. This program has been used to meas...
268 citations
TL;DR: A thorough review of the application of the Peierls model to the macroscopic plastic deformation of ionic crystals, metals, alloys, and covalently bonded crystals is given in this paper.
Abstract: A thorough review is made of the application of the Peierls model to the macroscopic plastic deformation of ionic crystals, metals, alloys, and covalently bonded crystals. The effects of the shape ...
259 citations
TL;DR: In this paper, the orientation dependence of the backscattering yield of a 1.0-MeV helium beam was investigated by studying the implantation behavior of Sb in silicon.
Abstract: The implantation behavior of Sb in silicon has been investigated by studying the orientation dependence of the backscattering yield of a 1.0-MeV helium beam. This orientation dependence ("channeling") provides quantitative information on the location of implanted atoms in the lattice and also on the amount of lattice disorder accompanying the implantation. The general principles of the channeling technique and the advantages of using a beam of He+ rather than H+ are discussed. Results for 25 °C and 450 °C implantations are presented and compared. The hot implant introduces very little lattice disorder, and a large fraction (up to 95%) of the Sb atoms is found on substitutional sites. In the 25 °C implants, however, a heavily damaged region is formed around the track of each implanted Sb. At doses greater than ~1014 ions/cm2, these damaged regions overlap to produce an essentially amorphous layer, which then requires an annealing temperature of ~650 °C to reorder the lattice and to achieve a high level of ...
255 citations
TL;DR: In this paper, the latent hardening produced by straining copper crystals in single-glide was investigated by measuring the flow stress on secondary systems, and the results showed that flow stress did not increase significantly when only the slip direction was altered.
Abstract: The latent hardening produced by straining copper crystals in single glide was investigated by measuring the flow stress on secondary systems. Specimens oriented for slip on these systems were spark cut from large prestrained crystals and tested in tension. These specimens did not always yield on the most highly stressed system; this behavior is a manifestation of the anisotropy introduced by the prestrain and was found only in certain portions of the stereographic projection.When the glide plane was changed, the flow stress increased. The increase ranged from 160% in early stage I to 40% in late stage II, except for systems with Burgers vectors at 90° to the prestrain slip direction, where systematically smaller increases were observed. The flow stress did not increase significantly when only the slip direction was altered.The anisotropy of the flow stress is closely related to the anisotropy of the dislocation distribution produced by single glide. In particular a reasonably good correlation appears to ...
220 citations
TL;DR: In this paper, it was shown that a relationship exists between cold neutron scattering by simple molecular liquids and the corresponding infrared and Raman spectra of these substances, in particular for liquids with a high density.
Abstract: It is shown that a relationship exists between cold neutron scattering by simple molecular liquids and the corresponding infrared and Raman spectra of these substances. In particular, for liquids i...
207 citations
TL;DR: In this article, various orientations of single crystals of niobium, purified by ultra-high vacuum annealing, have been tested in compression at 295 °K and in tension at temperatures between 77°K and 295°K.
Abstract: Various orientations of single crystals of niobium, purified by ultra-high vacuum annealing, have been tested in compression at 295 °K and in tension at temperatures between 77 °K and 295 °K. The s...
195 citations
TL;DR: The absorption spectrum of CF2 in the 2'500'A region has been photographed at high dispersion, and the rotational structure of a number of bands has been analyzed as discussed by the authors.
Abstract: The absorption spectrum of CF2 in the 2 500 A region has been photographed at high dispersion, and the rotational structure of a number of bands has been analyzed. The analysis of the well-resolved...
159 citations
TL;DR: Vacuum-purified niobium crystals of various orientations have been tested in tension and compression, mainly at room temperature and 158 °K The observed slip planes were almost always of the {101}.
Abstract: Vacuum-purified niobium crystals of various orientations have been tested in tension and compression, mainly at room temperature and 158 °K The observed slip planes were almost always of the {101}
158 citations
TL;DR: Work hardening in stage II of stress-strain curves of f.c. crystals is discussed in this paper, where a detailed account of a theory described previously in outline by Hirsch is given.
Abstract: Current theories of work hardening in stage II of stress–strain curves of f.c.c. crystals are reviewed critically. A detailed account is given of a theory described previously in outline by Hirsch ...
143 citations
TL;DR: In this paper, the magnitude of the Ω-type splitting in a state arising from a Σ state of even multiplicity has been considered, and three topics concerning states are discussed.
Abstract: Three topics concerning states are discussed: (1) The magnitude of the Ω-type splitting in a state arising from a Σ state of even multiplicity has been considered and is found to be given to a firs...
TL;DR: The flow stress results agree with those of Foreman and Makin, but the differential activation length and the free slip distance predicted show important effects not previously expected.
Abstract: Obstacles to dislocation motion which are pointlike in character, finite in strength, and random in spatial distribution in the slip plane, are treated by statistical methods developed previously for infinitely strong obstacles. Various important length parameters are distinguished and derived as functions of stress: the link length between obstacles relevant in internal friction problems, the passing distance defined by the flow stress, the differential activation length determining the rate dependence of the flow stress, and the free slip distance important in the elastoplastic transition region and in the preexponential factor for thermal activation. The flow stress results agree with those of Foreman and Makin, but the differential activation length and the free slip distance predicted show important effects not previously expected.
TL;DR: In this article, the lowest direct optical transition values for several III-V alloy systems, from measurements of optical absorption, electroreflectance, electroluminescence, etc.
Abstract: Values of E0, the lowest direct optical transition, are available for several III-V alloy systems, from measurements of optical absorption, electroreflectance, electroluminescence, etc. It is shown...
TL;DR: In this paper, the authors studied the stress-strain behavior of single crystals of tantalum, niobium, and molybdenum in both tension and compression in the temperature range 4.2-400 °K.
Abstract: The stress–strain behavior of single crystals of tantalum, niobium, and molybdenum has been studied in both tension and compression in the temperature range 4.2–400 °K. The crystals were stressed in both the and the directions.At high temperatures, the yield stress of all three metals is independent of the direction and sense of the applied stress. At low temperatures, the yield stress depends markedly on the orientation of the crystals and the sense of the applied stress. This anisotropic behavior cannot be satisfactorily explained in terms of any of the mechanisms proposed so far, such as the mobility of jogs in screw dislocations, or the dissociation of a/2 screw dislocations on {112} planes.
TL;DR: In this paper, the steady-state flow stress of commercial purity aluminium was determined by extrusion over a range of temperatures, T, from 255-616 °C, and strain rates,, between 0.1-10'sec−1.
Abstract: The steady-state flow stress, σ, of commercial purity aluminium was determined by extrusion over a range of temperatures, T, from 255–616 °C, and strain rates, , between 0.1–10 sec−1. The data are ...
TL;DR: In this paper, the (0-0) bands of the 4'550'A band system of C2H2O2 (glyoxal), C2HDO2, and C2D2O 2 have been analyzed and it was shown unambiguously that the bands have type C structures.
Abstract: Rotational analyses of the (0–0) bands of the 4 550 A band system of C2H2O2 (glyoxal), C2HDO2, and C2D2O2 have been performed. The analyses show unambiguously that the bands have type C structures, in agreement with the assignment to a 1Au–1Ag, (or1A″–1A′), π*–n transition. Rotational constants, A, B, C, and DK have been determined for each isotope and probable structures for the molecule in the ground and excited states have been determined. The CO bond is longer and the CC bond shorter in the excited state, in agreement with the predictions of molecular orbital theory.
TL;DR: In this article, the mass dependence of behavior of stellar core undergoing gravitational collapse was examined, using improved equation of state and mean free path for energy transfer, and the results showed that stellar core undergoes gravitational collapse.
Abstract: Mass dependence of behavior of stellar core undergoing gravitational collapse examined, using improved equation of state and mean free path for energy transfer
TL;DR: In this paper, an apparatus was built to detect the formation of small slip events within a crystal by monitoring small longitudinal oscillations of the test specimen which occur when the load is momentarily relaxed.
Abstract: Evidence for the formation of slip lines and slip bands has usually been obtained from slip-line replica and etch-pit techniques. An apparatus has been built to detect the formation of small slip events within a crystal by monitoring small longitudinal oscillations of the test specimen which occur when the load is momentarily relaxed. Each load drop results in a burst of acoustic energy, some of which are detected and recorded electronically. Results are presented of measurements of the frequency and magnitude of acoustic pulses from single-crystal specimens during plastic flow. They suggest that slip events occur cooperatively and that dislocation velocities during yielding may be as high as 103 cm/sec.
TL;DR: In this paper, the authors examined the types of thermonuclear reactions that can take place in supernova explosions and showed that element synthesis will take place readily under the extreme conditions believed to exist in supernovae.
Abstract: It is generally assumed that element synthesis will take place readily under the extreme conditions believed to exist in supernova explosions. We have examined the types of thermonuclear reactions ...
TL;DR: Hall-effect and sheet-resistivity measurements have been made on silicon samples implanted with Sb, Ga, and As ions at energies between 20 and 75'keV in this article.
Abstract: Hall-effect and sheet-resistivity measurements have been made on silicon samples implanted with Sb, Ga, and As ions at energies between 20 and 75 keV. These measurements determine the weighted aver...
TL;DR: The mechanism of the deformation in tension of [321] axis square-sectioned single crystals of α-phase copper-aluminium alloys with and surfaces has been studied in this article.
Abstract: The mechanism of the deformation in tension of [321] axis square-sectioned single crystals of α-phase copper–aluminium alloys with and surfaces has been studied. Extensive use has been made of inte...
TL;DR: In this paper, the specific features of the slip geometry in b.c. metals are reviewed and the properties of sessile and glissile splittings of screw dislocations on both {110} and {112} planes are discussed.
Abstract: The specific features of the slip geometry in b.c.c. metals are reviewed. The properties of sessile and glissile splittings of screw dislocations on both {110} and {112} planes are then discussed a...
TL;DR: In this paper, the effects of temperature, strain rate, and purity on the yield and flow stresses of α titanium at low temperatures (T < 0.4 ) were examined to ascertain the rate controlling dislocation mechanis...
Abstract: The effects of temperature, strain rate, and purity on the yield and flow stresses of α titanium at low temperatures (T < 0.4 TM) are examined to ascertain the rate controlling dislocation mechanis...
TL;DR: The mechanical properties of a series of Ta-Re alloys and some Ta-Mo and Ta-W alloys have been investigated by deforming single crystals in compression.
Abstract: The mechanical properties of a series of Ta–Re alloys and some Ta–Mo and Ta–W alloys have been investigated by deforming single crystals in compression Experimental results on slip-line observatio
TL;DR: In this article, the work-hardening behavior of iron single crystals depends very much on orientation and orientation of the crystal, and the deformation behavior of the single crystal is summarized.
Abstract: Results accumulated in the past four years on the plastic deformation of iron single crystals are summarized.The work-hardening behavior of iron single crystals depends very much on orientation and...
TL;DR: The spin-lattice relaxation time T1 for protons and deuterons in CH4, CH3D, CH2D2, CHD3, and CD4 has been measured as a function of density ρ and temperature T for 0.1 Amagat Amagats.
Abstract: The spin-lattice relaxation time T1 for protons and deuterons in CH4, CH3D, CH2D2, CHD3, and CD4 has been measured as a function of density ρ and temperature T for 0.1 Amagat Amagats and The result...
TL;DR: In this article, it was shown that Pi-2 micropulsations are polarized in an anticlockwise sense in the horizontal plane at northern-hemisphere mid-latitude stations and that the last part of the propagation path of the Pi 2 from the auroral zone to the observing station is traversed in the Alfven mode.
Abstract: From the analysis of 20 separate events it is shown that Pi-2 micropulsations are polarized in an anticlockwise sense in the horizontal plane at northern-hemisphere mid-latitude stations. Combined with the knowledge that in the southern hemisphere polarization is predominantly in the clockwise sense, it can be inferred that at least the last part of the propagation path of the Pi 2 from the auroral zone to the observing station is traversed in the Alfven mode. The presence of occasional pulsations possessing clockwise polarization in the northern hemisphere and anticlockwise polarization in the southern hemisphere suggests that the Alfven mode alone is insufficient to explain the mode of propagation of a Pi 2. It is shown how ionospheric screening may influence the direction of polarization of a micropulsation. It is found that the initial kick of a Pi-2 micropulsation is strongly related to the sign of the accompanying geomagnetic bay. Deviations from this trend are discussed and it is shown that the Pi-...
TL;DR: In this paper, the authors applied Berg-Barrett X-ray topography to deformed copper single crystals and observed a systematic interaction of both types of slip systems, giving rise to layer-like dislocation structures about parallel to the primary slip plane.
Abstract: The paper deals with the application of Berg–Barrett X-ray topography to deformed copper single crystals. The imaged surfaces were sectioned from the deformed bulk crystals parallel to low-index planes.In stage I of the work-hardening curve, the braids of primary edge-dislocation dipoles, well known from electron transmission microscopy, have been observed over lengths of several tenths of a millimeter. Whereas in stage 1 the slip appears to be rather homogeneous and without strong interaction between primary and secondary slip systems, the transition region to stage 11 displays, as a characteristic feature, a systematic interaction of both types of slip systems, giving rise to layer-like dislocation structures about parallel to the primary slip plane. These layers, as in stage 11, are connected with a special type of lattice rotation. In stage II, dislocation walls or wall fragments perpendicular to the primary slip direction are observed. Generally, these walls are accompanied on either side by an exten...
TL;DR: In this article, the variation of electrical resistivity with deformation, as a function of purity and orientation, has been studied for Cu single crystals deformed in tension and fatigue.
Abstract: The variation of electrical resistivity with deformation, as a function of purity and orientation, has been studied for Cu single crystals deformed in tension and fatigue. In stage I the rate of increase of resistivity depends very strongly on the impurity content, decreasing with increasing purity. In stage II the resistivity increases quadratically with stress, the rate of increase depending on orientation. The resistivity produced by dislocations appears not to be strongly anisotropic. The value of resistivity per unit dislocation is about 1 × 10−19 ΩSi-cm.
TL;DR: A review of the methods applied for the investigation of long-range stresses in deformed single crystals is given in this article, where the results found by magnetic methods are discussed in some detail; slip-line data and transmission microscopy are mentioned briefly.
Abstract: A review of the methods applied for the investigation of long-range stresses in deformed single crystals is given. The results found by magnetic methods are discussed in some detail; slip-line data and transmission microscopy are mentioned briefly. The effect of internal stresses on the flow stress is discussed and it is shown that the elastic interaction between the primary dislocations determines the flow stress almost completely. Secondary dislocations are found to be incapable of relaxing the stress fields of the primary dislocations appreciably.