Showing papers on "Slip (materials science) published in 1974"
TL;DR: In this article, it was shown that the deformation criterion for viscous glide is given by Bσ 2 k 2 (1 − v γ Gb 3 > T 2 e 2 cb 6 where B ∼ 8 × 1012, σ is the applied stress, k is Boltzmann's constant, v is Poisson's ratio, γ is the stacking fault energy, G is the shear modulus, b is the Burgers vector, T is the absolute temperature, e is the solute-solvent size difference, and c is the concentration
405 citations
TL;DR: In this article, an analysis of the evolution of microstructure during deformation is made and the relationship between the micro-structure and annealing texture development is considered in detail.
Abstract: An analysis of the evolution of microstructure during deformation is made and the relationship between the microstructure and annealing texture development considered in detail. Although existing data are inadequate for a full assessment, it seems that all annealing texture components encountered in single-phase cubic metals can be explained in terms of one or other of three nucleation mechanisms. In situ subgrain-growth nucleation occurs for orientations within the stable-deformation texture, i.e. in regions of low lattice curvature. Transition band nuclei are of orientations remote from the stable deformation texture components in regions where slip rotations are divergent and nucleation at grain boundaries will provide orientations belonging to the principal spread about the deformation texture.The analysis applies for the most part to both fcc and bcc metals but there are some differences. One feature that is not common to both systems, the occurrence of the cube-texture in some fcc metals, is...
270 citations
TL;DR: In this paper, an inelastic dynamic analysis method was developed for reinforced concrete frame structures to account for stiffness characteristics related to cracking of the concrete, yielding and strain hardening of the reinforcement, bond slip of tensile reinforcement in a joint core, and stiffness degradation due to load reversals.
Abstract: An inelastic dynamic analysis method was developed for reinforced concrete frame structures. The analytical model was able to account for stiffness characteristics related to cracking of the concrete, yielding and strain hardening of the reinforcement, bond slip of tensile reinforcement in a joint core, and stiffness degradation due to load reversals. The location of point of contraflexure in a member was taken into consideration to account for the distribution of inelastic deformation. The analysis method was tested by comparing calculated response waveforms with observed response waveforms of a small-scale three-story one-bay reinforced concrete frame structure, which was subjected to an intense base motion on the University of Illinois Earthquake Simulator. The observed waveforms at large amplitudes were favorably simulated by the analytical model based on the material properties and geometry of the test structure.
148 citations
TL;DR: In this article, the tensile properties of Ti-Mo alloys hardened by the precipitation of ω-partieles were correlated to the microscopic deformation behavior, showing that the reduction in macroscopic ductility with increasing precipitation of α-particles could be explained by the fact that the moving dislocations were able to shear the hard particles leading to an extreme inhomogeneous slip distribution.
141 citations
TL;DR: In this paper, the critical resolved shear stress (CRSS) for slip in oriented high-density polyethylene (HDPE) has been measured as a function of temperature between 0° and 100°C.
Abstract: The critical resolved shear stress (CRSS) for (010) [001] slip in oriented high- density polyethylene (HDPE) has been measured as a function of temperature between 0° and 100°C The variation of the CRSS with temperature has been interpreted in terms of yield by means of the thermal activation of dislocations at the edges of the crystal platelets under the action of an applied shear stress
139 citations
TL;DR: In this article, the authors used a simple and well reproducible crack geometries in copper single-crystals: the crack surfaces are macroscopically plane and the crack front can be forced by appropriate external force distributions into any preselected direction.
112 citations
TL;DR: A theoretical analysis of the textures developed in bcc metals deforming by pencil glide is briefly reviewed and the results compared with experimental results in this article, where the pencil-glide case was chosen because it is possible to make an unambiguous theoretical analysis.
Abstract: A theoretical analysis of the textures developed in bcc metals deforming by pencil glide is briefly reviewed and the results compared with experimental results. The pencil-glide case was chosen because it is possible to make an unambiguous theoretical analysis. The main features of the results are identical to those for bcc metals deforming by {110} 〈111〉 slip, or by interchanging directions of compression and extension, for fcc metals deforming by {111} 〈110〉 slip.Upper- and lower-bound theories are both presented and it is found that the upper-bound theory is closer to the experimental facts. There remain, however, some important deviations between theory and experiment and the reasons for these are discussed. In considering one possibility, an imposed-strain theory of surface textures is presented.
109 citations
01 Nov 1974
TL;DR: In this paper, an isotropic elastic material containing a random distribution of identical spherical particles of another elastic material is considered, where the bonding between the spheres and the matrix is imperfect, so that slip may occur at interfaces when stress is applied to the medium.
Abstract: An isotropic elastic material containing a random distribution of identical spherical particles of another elastic material is considered. The bonding between the spheres and the matrix is imperfect, so that slip may occur at interfaces when stress is applied to the medium. The shear stresses at the interface is assumed to be proportional to the amount of slip. The velocity and attenuation of the average harmonic elastic waves propagating through such a medium are calculated. The results are valid to the lowest order in frequency for wave lengths long compared with the radius of the sphere. The dynamic elastic moduli are obtained from these results and are compared with available results for welded contact. The variations in the P and S wave velocities for propagation across earthquake faults is discussed.
105 citations
TL;DR: In this article, a previously published model of fatigue crack propagation is refined and the resulting slip geometry at the crack tip is calculated, where the slip on both sides of the crack is assumed to occur on slip bands instead of the discrete slip planes used in the old model.
103 citations
TL;DR: In this paper, it is suggested that the second set of 1 6 〈112〉 dislocations could form as a result of either interaction between the twinning partials and 1 2 ǫ-101〉 slip dislocation gliding in the composition plane or dissociation of the twin-ning dislocational at the matrix-twin interface, which may occur to relieve the stresses that are likely to exist at the tip of a twin terminating within the crystal.
TL;DR: In this paper, the dislocation arrangements produced around microhardness indentations made in silicon at room temperature have been studied by transmission electron microscopy and it is suggested that, during indentation, the theoretical shear strength is exceeded locally and that the observed dislocations arise as a result of the accommodation of the displacements due to block slip.
Abstract: The dislocation arrangements produced around microhardness indentations made in silicon at room temperature have been studied by transmission electron microscopy. Loops consisting of 30°- and 60°-dislocations are produced and move on the {111} planes. It is suggested that, during indentation, the theoretical shear strength is exceeded locally and that the observed dislocations arise as a result of the accommodation of the displacements due to block slip. On annealing up to 1030° C the loops do not appear to be mobile, rather new loops consisting of edge and screw components are formed which can move large distances.
TL;DR: In this article, a theoretical model of the folding of a free, anisotropic, linearly viscous layer of appropriate wave length/thickness ratio is analyzed, and the model of inherited asymmetry is both appropriate for the Greenport Center syncline and treatable within the present theoretical framework.
Abstract: The Greenport Center syncline is an asymmetric fold with a half wave length of about 40 m developed in the Devonian Becraft and Alsen Limestones on Becraft Mountain, New York. Twinning strains have been measured in 19 samples distributed so as to sample all of the structurally significant regions of the fold. The orientation and relative magnitudes of the observed strains are consistent with those expected from the buckling of a thick isotropic layer, but the observed magnitudes are too small by a factor of more than four. Local and nonsystematic variations in strain are much larger than those expected in the buckling of a continuous layer, and the Greenport Center syncline also contains abundant geologic evidence that slip between beds was important.
A theoretical model of the folding of a free, anisotropic, linearly viscous layer of appropriate wave length/thickness ratio is analyzed. Although the smoothly distributed bedding-parallel shear of the model does not adequately represent the process of bedding slip in the real fold, it does permit the estimate of the degree of anisotropy necessary to produce observed limb dips with observed bending strains. If the viscosity coefficient for shear parallel to bedding is 0.03 times that for bending, the bending strains are reduced to the observed value; the required bedding slip could be produced by slip surfaces spaced about 30 cm apart if the average displacement on a slip surface were about 23 cm. The model of inherited asymmetry is both appropriate for the Greenport Center syncline and treatable within the present theoretical framework. Inherited asymmetry is shown to be possible for an anisotropic layer though not for an isotropic one.
TL;DR: In this article, the effect of slip amplitude on the mechanism of fretting was investigated and measurements of wear volume, frictional coefficient and electrical contact resistance were carried out to clarify the wear mechanism.
TL;DR: In this paper, the authors calculate the time dependent stress, strain, and pore pressure fields after a plane fracture whose offset varies sinusoidally in the direction of slip.
Abstract: A fracture that redistributes shear stress in a porous medium produces local fluid pore pressure changes. Decay of this pore pressure due to flow causes strain. Using the theory of Biot, I calculate the time dependent stress, strain, and pore pressure fields after a plane fracture whose offset varies sinusoidally in the direction of slip. The results permit construction of arbitrary one-dimensional slip functions by Fourier synthesis. In particular, I investigate the simple crack made from two edge dislocations. The fracture surface is slowly reloaded after an initial shear stress drop, and the shear strength of the material adjacent to the fracture varies with time. This behavior is useful in explaining earthquake foreshocks, aftershocks, and delayed creep. For the simple crack the frequency of aftershocks associated with the reloading decays like t−1.
TL;DR: In this article, the deformation of high-density polyethylene with a single crystal texture by shear in directions perpendicular to the chain direction has been examined by wide-angle X-ray diffraction.
Abstract: The deformation of high-density polyethylene with a single crystal texture by shear in directions perpendicular to the chain direction has been examined by wide-angle X-ray diffraction. It is found that samples can undergo either a martensitic transformation to a monoclinic cell, (100) [010] slip or (110) twinning depending upon the orientation of the specimen to the compression direction. A specific orientation relationship has been found between the new monoclinic cell and the parent orthorhombic cell and this has been compared with relationships found by other workers. Stress-strain curves have been obtained from other specimens and it is suggested that for specimens in certain orientations yield may take place by means of a martensitic transformation at a critical resolved shear stress of 14 ± 1 MNm-2.
TL;DR: In this article, a polishing compound was studied on triaxial compression specimens for slip up to 3 mm at confining pressures to 2.9 kbar, where the preferred orientation of the carrot-shaped grooves is such that the tip points in the direction of motion of the surface containing the grooves.
Abstract: The frictional wear of Westerly granite surfaces polished with 0.3-μm Linde A polishing compound was studied on triaxial compression specimens for slip up to 3 mm at confining pressures to 2.9 kbar. A stable sliding to stick-slip transition occurs at 0.3-kbar confining pressure. Frictional wear occurs on the polished sliding surface only when the specimens undergo stick-slip. The initial wear on the surface consists of microscopic carrot-shaped grooves whose length rarely exceeds the maximum slip accompanying one stress drop during stick-slip sliding. The preferred orientation of the carrot-shaped grooves is such that the tip points in the direction of motion of the surface containing the grooves. A groove length equivalent to individual slip distance results in a small groove length to total slip ratio (<1:5) that may be used as a criterion for stick-slip sliding. A small groove length to total slip ratio also occurs on two natural slickenside surfaces, and on the basis of the laboratory experiments these natural surfaces are thought to be samples from fault zones that were once seismically active. The experimental observation that maximum groove length closely approximates the slip during the seismic event suggests that the seismic moment of prior earthquakes on a fault may be calculated without prior knowledge of seismicity.
01 Sep 1974-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, a series of iron-platinum alloys containing 25 or 27 at. pct platinum and with ordering of the γ-phase varying from substantial disorder to nearly complete order have been thermally cycled between 25°C and - 196°C.
Abstract: A series of iron-platinum alloys containing 25 or 27 at. pct platinum and with ordering of the γ-phase varying from substantial disorder to nearly complete order have been thermally cycled between 25°C and - 196°C. The kinetics of the γ⇌α transformations, the hysteresis revealed by electrical resistanceJtemperature plots, the thermoelastic growth and the reappearance of an identical microstructure after thermal cycling (the microstructural memory effect) were studied as a function of the ordering of the γ-phase. Thermoelastic growth does not appear to be affected by changes in the degree of order of partially ordered specimens but the microstructural memory was imperfect in the most highly ordered specimen examined. In agreement with earlier observations by Dunne and Wayman,3 the difference between the As and Ms temperatures and the hysteresis decrease markedly as the order is increased. It is shown by transmission electron microscopy that in all but the most highly-ordered specimens the α- γ transformation produces plates of austenite with a high density of dislocations. These plates are separated from the surrounding untransformed parent austenite by arrays of dislocation loops lying in the interfaces between untransformed parent austenite and the original martensite plates. All the dislocations have a Burgers vector direction which is the same as that of the usual slip dislocation in austenite. Such dislocations lying in a habit plane must be sessile. In the well-ordered specimen dislocation pairs, typical of glide dislocations in a crystal with long-range order, were formed in the austenite formed by the reverse transformation. These dislocations were segregated into roughly plate-like clusters, but the number of clusters in unit volume was appreciably less than the number of original plates of martensite. In this case, no arrays of sessile loops of dislocations mark the locations of the original martensite-austenite interface. It is deduced from the microscopic and kinetic results that the inherited nuclei responsible for the microstructural memory effect are located in localized volumes of highly dislocated austenite formed by the α- γ transformation. No unique dislocation configurations which could be associated with specific nuclei were found. The effects of ordering on the various kinetic effects and the microstructural memory are discussed in terms of the concept of inherited nuclei, the change of the flow stress of the γ-phase with ordering and temperature and the variation of To and the transformation driving-force with ordering.
TL;DR: In this article, it was shown that dislocation climb plays an important role in the deformation process for basal slip in the range 1200° to 1500°C, where the rate of accumulation of dislocation dipoles by edge-trapping is equal to their rate of annihilation by climb.
Abstract: Dislocation structures in sapphire deformed by basal slip at 1200° to 1500°C were studied by transmission electron microscopy. Long dislocation dipoles of edge character are formed by interactions of dislocations on parallel basal planes (“edge-trapping”); screw dislocations annihilate by cross-slip. The accumulation of dislocation dipoles leads to work-hardening, but the dipoles also break up into smaller loops by climb, causing recovery. Eventually a steady state of zero work-hardening is reached, where the rate of accumulation of dipoles by edge-trapping is equal to their rate of annihilation by climb. From these observations, it is suggested that dislocation climb plays an important role in the deformation process for basal slip in the range 1200° to 1500°C.
TL;DR: In this paper, an analytical solution for performance characteristics of a narrow journal bearing is obtained, taking account of the velocity slip at the surface of a porous medium by using Beavers-Joseph criterion.
Abstract: Analytical solution for performance characteristics of a narrow journal bearing is obtained. The analysis takes account of the velocity slip at the surface of a porous medium by using Beavers-Joseph criterion [1]. Results are presented for various bearing characteristics and compared with earlier results obtained by using no-slip condition. A comparison is also made with an earlier approximate analysis [8] which considers the slip effects but assumes the bearing wall thickness to be infinitesimally small.
TL;DR: In this article, a model of slow-moving disturbances of deformation is proposed to interpret the observed propagations of earthquake foci and non-seismic creep, based on the assumption that thin fault gouge participates in the viscous slip.
TL;DR: In this article, the main increase in CRSS on cooling in Ti is thought due to an increase in the stress required to overcome the Peierls barrier but there is a component due to interstitials which is removed by adding Al.
TL;DR: Anomalous slip traces have been detected in Niobium after straining at 50 K as mentioned in this paper, and TEM analysis has been performed on samples cut parallel to (011). Dislocation substructures, intersections, pinned and serrated dislocations, have been analysed.
TL;DR: In this article, the texture changes can be interpreted in terms of grain boundary sliding, dislocation motion and diffusion creep in the Al-33 wt% Cu eectic alloy.
TL;DR: In this article, the authors measured hardness anisotropy by Knoop diamond indentation on the surface of Nb6C5 and showed that the hardness is determined by crystallographic slip on {111} 〈1¯10〉 and {110} ´1´10'' systems.
Abstract: Measurements of hardness anisotropy by Knoop diamond indentation on the {100} surfaces of Nb6C5 crystals show that the hardness is determined by crystallographic slip on {111} 〈1¯10〉 and {110} 〈1¯10〉 systems. {111} is the preferred slip plane for Nb6C5 and crystals with higher carbon content which show a marked decrease in Knoop hardness. The carbon atom/vacancy arrangement in these crystals is shown, by electron diffraction, to possess short-range order. Crystals annealed at low temperatures contain domains of non-cubic long-range order which increase the Knoop hardness and eliminate the anisotropy in hardness. Dislocation arrangements around Knoop indentations have been directly observed by electron microscopy in an attempt to confirm the slip processes deduced from hardness anisotropy.
TL;DR: In this paper, a superplastic Zn-40 wt.% Al alloy was used to measure the texture of both phases in both phases as a function of the strain rate.
TL;DR: In this paper, the source process of the Wakasa Bay earthquake (M = 6.9, 35.80°N, 135.76°E, depth 4 km) is studied on the basis of the seismological data.
Abstract: The source process of the Wakasa Bay earthquake ( M = 6.9, 35.80°N, 135.76°E, depth 4 km) which occurred near the west coast of Honshu Island, Japan, on March 26, 1963, is studied on the basis of the seismological data. Dynamic and static parameters of the faulting are determined by directly comparing synthetic seismograms with observed seismograms recorded at seismic near and far distances. The De Hoop-Haskell method is used for the synthesis. The average dislocation is determined to be 60 cm. The overall dislocation velocity is estimated to be 30 cm/sec, the rise time of the slip dislocation being determined as 2 sec. The other fault parameters determined, with supplementary data on the P -wave first motion, the S -wave polarization angle, and the aftershocks, are: source geometry, dip direction N 144°E, dip angle 68°, slip angle 22° (right-lateral strike-slip motion with some dip-slip component); fault dimension, 20 km length by 8 km width; rupture velocity, 2.3 km/sec (bilateral); seismic moment, 3.3 × 1025 dyne-cm; stress drop, 32 bars. The effective stress available to accelerate the fault motion is estimated to be about 40 bars. The approximate agreement between the effective stress and the stress drop suggests that most of the effective stress was released at the time of the earthquake.
TL;DR: Reexamination of geodetic data has shown that aseismic slip occurred on or near the San Andreas fault in the period of about 20 years after 1906, and inferred displacements are comparable to but at greater depths than the sudden slip that occurred at the time of the earthquake.
Abstract: Reexamination of geodetic data has shown that aseismic slip occurred on or near the San Andreas fault in the period of about 20 years after 1906. The inferred displacements are comparable to but at greater depths than the sudden slip that occurred at the time of the earthquake. The postseismic slip is constrained only between late 1906 and 1925, and data are insufficient to determine the movements, if any, below about 20 kilometers on the fault. Two independent observations also indicate stubstantial anomalous crustal deformation away from the fault at least 30 years before the earthquake.