Computer Simulation of Plastic Deformation Through Planar Glide in an Idealized Crystal

Altıntaş, Sabri; Hanson, Kenton; Morris, J. W.

doi:10.1115/1.3443341

Cited by 16 publications

(7 citation statements)

References 2 publications

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“…the SRS parameter m is proportional to the temperature and inversely proportional to the obstacle strength. The same relationship was found in [7,13,15] and seems to agree with experimental data [21].…”

Section: Random Obstacle Distributionssupporting

confidence: 90%

“…This expression is postulated based on previous theoretical work and numerical results [7,13]. It was proven only in the context of weak obstacles, situation in which the assumption of uncorrelated obstacle failure holds.…”

Section: Random Obstacle Distributionsmentioning

confidence: 99%

“…The approach of Schoeck [12] is aimed at relaxing this limitation, but it eventually leads only to asymptotic predictions. Several computer simulations of thermally activated dislocation motion were also performed [13,14].…”

Section: Introductionmentioning

confidence: 99%

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Thermally activated motion of dislocations in fields of obstacles: The effect of obstacle distribution

Picu

2007

Phys. Rev. B

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The thermally activated motion of dislocations across fields of obstacles distributed at random and in a correlated manner, in separate models, is studied by means of computer simulations. The strain rate sensitivity and strength are evaluated in terms of the obstacle strength, temperature and applied shear stress. Above a threshold stress, the dislocation motion undergoes a transition from smooth to jerky, i.e. obstacles are overcome in a correlated manner at high stresses, while at low stresses they are overcome individually. This leads to a significant reduction of the strain rate sensitivity. The threshold stress depends on the obstacle strength and temperature. A model is proposed to predict the strain rate sensitivity and the smooth-to-jerky transition stress. Obstacle clustering has little effect on strain rate sensitivity at low stress (creep conditions), but it becomes important at high stress.It is concluded that models for the strength and strain rate sensitivity should include higher moments of the obstacle density distribution in addition to the mean density.

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Section: Random Obstacle Distributionssupporting

confidence: 90%

Section: Random Obstacle Distributionsmentioning

confidence: 99%

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Thermally activated motion of dislocations in fields of obstacles: The effect of obstacle distribution

Picu

2007

Phys. Rev. B

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“…changes in the properties of the stroneesj configuration from array to array has important consequences with respect to deformation behavior of idealized cry stals. 42 The distribution of forces on the strongest configuration of an array con taining 10 6 obstacles is shown in Figure 15, whereas the prediction by Labusch^8 gives a rather good fit to the empirical dis tribution.…”

Section: Dislocation Glide Through Large Arraysmentioning

confidence: 99%

“…as temperature decreases. The scatter in /3] from array to array has also important conse quences 42 ' 43 , where at low temperatures the dislocation will glide on those planes on which the glide velocity is highest and thus the deformation of tuc crystal appears inhomogeneous. The deformation becomes homogeneous as temperature is raised or stress is decreased.…”

Section: B) Thermally Activated Glidementioning

confidence: 99%

Plastic deformation of crystals: analytical and computer simulation studies of dislocation glide

Altıntaş¹

1978

Self Cite

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The plastic deformation of crystals is usually accomplished through the motion of dislocations. The glide of a dislocation is impelled by the applied stress and opposed by microstructural defects such as point defects, voids, pre cipitates and other dislocations.The planar glide of a dislocation through randomly distributed obstacles is considered. The objective of the present research work is to calculate the critical resolved shear stress (CRSS) for athermal glide and the velocity of the disloca tion at finite tempereature as a function of the applied stress and the nature and strength of the obstacles.Dislocation glide through mixtures of obstacles has been studied analyti cally and by computer simulation. Arrays containing two kinds of obstacles as well as square distribution of obstacle strengths are considered. The critical resolved shear stress for an array containing obstacles with a given distribution -ivof strengths is calculated using the sum of the quadratic mean of the stresses for the individual obstacles and is found to be in good agreement with the com puter simulation data.Computer simulation of dislocation glide through randomly distributed obstacles containing up to 10 6 obstacles show that the CRSS decreases as the size of the array increases and approaches a limiting value. Histograms of forces and of segment lengths are obtained and compared with theoretical predictions.Effects of array shape and boundary conditions on the dislocation glide are also studied.Analytical and computer simulation results are compared with experimen tal results obtained on precipitation-, irradiation-, forest-, and impurity clusterhardening systems and are found to be in good agreement.

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Activation energy and activation volume of dislocation movement through randomly distributed point obstacles

Wielke

1981

Phys. Stat. Sol. (a)

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The macroscopic properties of the plastic deformation of a simple model crystal which obeys the Friedel relation are compared with computer simulation data and some in the literature unnoticed differences are discussed. It is pointed out that the random distribution of obstacles causes on average activation energy ΔG0, about 20% larger than ΔG0 of the single process of thermal activation. The activation volume and the average dislocation segment length l between obstacles is proportional to τ −1/3 only at low temperatures whereas at higher temperatures l calculated from computer simulation data increases more rapidly with decreasing stress than expected by the Friedel relation, l ∼τ1/3.

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Computer Simulation of Plastic Deformation Through Planar Glide in an Idealized Crystal

Cited by 16 publications

References 2 publications

Thermally activated motion of dislocations in fields of obstacles: The effect of obstacle distribution

Thermally activated motion of dislocations in fields of obstacles: The effect of obstacle distribution

Plastic deformation of crystals: analytical and computer simulation studies of dislocation glide

Activation energy and activation volume of dislocation movement through randomly distributed point obstacles

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