Thermally activated dislocation glide through a random array of point obstacles: Computer simulation

1974 ◽  
Vol 45 (5) ◽  
pp. 2027-2038 ◽  
Author(s):  
J. W. Morris ◽  
Dale H. Klahn
Keyword(s):  
Computer Simulation ◽  
Dislocation Glide ◽  
Thermally Activated ◽  
Random Array

Deformation Modeling Applied to Stress Relaxation of Four Solder Alloys

1980 ◽  
Vol 102 (2) ◽  
pp. 207-214 ◽  
Author(s):  
R. W. Rohde ◽  
J. C. Swearengen
Keyword(s):  
Stress Relaxation ◽  
Stainless Steels ◽  
General Concept ◽  
Model Parameters ◽  
Recovery Model ◽  
Solder Alloys ◽  
Dislocation Glide ◽  
Thermally Activated ◽  
Dependent Behavior ◽  
Excellent Description

Stress relaxation of four solder alloys, 50 percent Pb-50 percent In; 37.5 percent Sn-37.5 percent Pb-25 percent In; 63 percent Sn-37 percent Pb; and 62.5 percent Sn-37 percent Pb-0.5 percent Ag, has been examined at 222 K, 298 K, and 344 K. A model previously utilized to describe inelastic deformation of aluminum and stainless steels is applied and found to provide an excellent description of the experimental data. This model is based upon the general concept of stress assisted thermally activated dislocation glide in a microstructure evolving by the process of strain hardening and recovery. Model parameters useful for calculations of time dependent behavior of these solders are presented and their significance is discussed.

Modeling of Dislocation Mobility in Metals: Effect of Obstacles and Thermal Processes

2001 ◽  
Vol 683 ◽  
Author(s):  
Masato Hiratani ◽  
Hussein M. Zbib
Keyword(s):  
Thermal Activation ◽  
Dislocation Dynamics ◽  
Thermal Processes ◽  
Weak Point ◽  
Dislocation Glide ◽  
Thermally Activated ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Activation Rate ◽  
Activation Event

ABSTRACTThermally activated dislocation glide velocity through weak point obstacle arrays is studied analytically and computationally. Thermal activation rate is estimated using the modified Friedel relations under the weak obstacle approximation. The average flight velocity after an activation event as a function of stress and temperature is obtained by the discrete dislocation dynamics (DD). This numerical calculation includes the effect of self-stress, interaction with electrons and phonons, and the inertial effect. These results are implemented into a phenomenological model to study the dislocation velocity under various conditions. The model can reproduce both obstacle control and drag control motion in low and high velocity regions, and a flow stress anomaly at transient regions.

scholarly journals Temperature dependence of mechanical properties in ultrathin Au films with and without passivation

2008 ◽  
Vol 23 (9) ◽  
pp. 2406-2419 ◽  
Author(s):  
Patric A. Gruber ◽  
Sven Olliges ◽  
Eduard Arzt ◽  
Ralph Spolenak
Keyword(s):  
Mechanical Properties ◽  
Temperature Dependence ◽  
Elevated Temperatures ◽  
Bulk Material ◽  
Diffusional Creep ◽  
Strong Temperature Dependence ◽  
Metallic Films ◽  
Dislocation Glide ◽  
Thermally Activated ◽  
Passivation Layers

Temperature and film thickness are expected to have an influence on the mechanical properties of thin films. However, mechanical testing of ultrathin metallic films at elevated temperatures is difficult, and few experiments have been conducted to date. Here, we present a systematic study of the mechanical properties of 80–500-nm-thick polycrystalline Au films with and without SiNx passivation layers in the temperature range from 123 to 473 K. The films were tested by a novel synchrotron-based tensile testing technique. Pure Au films showed strong temperature dependence above 373 K, which may be explained by diffusional creep. In contrast, passivated samples appeared to deform by thermally activated dislocation glide. The observed activation energies for both mechanisms are considerably lower than those for the bulk material, indicating that concomitant stress relaxation mechanisms are more pronounced in the thin film geometry.

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

1976 ◽  
Vol 98 (1) ◽  
pp. 86-91 ◽  
Author(s):  
S. Altintas ◽  
K. Hanson ◽  
J. W. Morris
Keyword(s):  
Computer Simulation ◽  
Plastic Deformation ◽  
Strain Rate ◽  
Morphological Characteristics ◽  
Line Tension ◽  
Constant Density ◽  
Thermally Activated ◽  
Random Arrays ◽  
Slip Planes ◽  
Simple Step

In this paper we report the behavior of the plastic deformation of an idealized crystal made by stacking parallel slip planes. Each slip plane is assumed to contain active sources of dislocations leading to a constant density of non-interacting dislocations in the plane which glide through randomly distributed localized point obstacles, representing small precipitates. The dislocation is assumed to have a constant line tension and the dislocation-obstacle interaction is taken to have a simple step form. Using results of computer simulation of thermally activated glide through random arrays of point obstacles we modeled deformation as a function of temperature and applied stress, determining the strain rate and the morphological characteristics of slip.

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