Uniaxial Stress Deformation Experiment for Validation of 3-D Dislocation Dynamics Simulations

2002 ◽  
Vol 124 (3) ◽  
pp. 290-296 ◽  
Author(s):  
David H. Lassila ◽  
Mary M. LeBlanc ◽  
Gregory J. Kay
Keyword(s):  
Experimental Data ◽  
Single Crystal ◽  
Single Crystals ◽  
High Purity ◽  
Axial Stress ◽  
Uniaxial Stress ◽  
Dislocation Dynamics ◽  
Uniform State ◽  
Dynamics Simulations ◽  
Unconstrained Motion

An apparatus has been developed for performing compression deformation experiments on oriented metallic single crystals to provide data for validation of 3-D dislocation dynamics simulations. The experiment is performed under conditions that allow unconstrained motion of the upper and lower compression platen, and thus a relatively uniform state of axial stress is maintained during the deformation. Experiments have been performed on high-purity Mo single crystal and polycrystalline Cu. Various aspects of the experimental procedures and results are presented. Possible usages of the experimental data for the validation of 3-D dislocation dynamics simulations are discussed.

scholarly journals Single Crystal Deformation Experiments for Validation of Dislocation Dynamics Simulations

2003 ◽  
Vol 779 ◽  
Author(s):  
David H. Lassila ◽  
Mary M. LeBlanc ◽  
Moono Rhee
Keyword(s):  
Slip System ◽  
High Purity ◽  
Axial Stress ◽  
Dislocation Dynamics ◽  
Strain Response ◽  
Hardening Behavior ◽  
Uniform State ◽  
Validation Criteria ◽  
Experimental Apparatus ◽  
Dynamics Simulations

AbstractA new experimental apparatus has been developed for performing compression deformation experiments on high-purity Mo single crystals. These experiments provide data that can validate 3-D dislocation dynamics (DD) simulations. The experiments are performed under conditions that allow unconstrained deformation; thus, a relatively uniform state of axial stress is maintained during deformation. In the following sections, we describe the new experimental apparatus and our results from experiments performed at ambient temperature at a strain rate of s–1. Validation criteria based on the Mo experiments may include comparing the stress-strain response using 3-D strain information, the predicted slip-system yield, and work-hardening behavior.

Multiscale modeling of plasticity in a copper single crystal deformed at high strain rates

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Sagar Chandra ◽  
M. K. Samal ◽  
V. M. Chavan ◽  
R. J. Patel
Keyword(s):  
Single Crystal ◽  
Multiscale Modeling ◽  
Crystal Plasticity ◽  
Mechanical Response ◽  
Md Simulations ◽  
Dislocation Dynamics ◽  
Copper Single Crystal ◽  
Deformation Response ◽  
Discrete Dislocation ◽  
Dynamics Simulations

AbstractA hierarchical multiscale modeling approach is presented to predict the mechanical response of dynamically deformed (1100 s−1−4500 s−1) copper single crystal in two different crystallographic orientations.Anattempt has been made to bridge the gap between nano-, micro- and meso- scales. In view of this, Molecular Dynamics (MD) simulations at nanoscale are performed to quantify the drag coefficient for dislocations which has been exploited in Dislocation Dynamics (DD) regime at the microscale. Discrete dislocation dynamics simulations are then performed to calculate the hardening parameters required by the physics based Crystal Plasticity (CP) model at the mesoscale. The crystal plasticity model employed is based on thermally activated theory for plastic flow. Crystal plasticity simulations are performed to quantify the mechanical response of the copper single crystal in terms of stressstrain curves and shape changes under dynamic loading. The deformation response obtained from CP simulations is in good agreement with the experimental data.

Dislocation Dynamics Simulations of Dislocation Interactions in Thin Fcc Metal Films

2001 ◽  
Vol 673 ◽  
Author(s):  
Prita Pant ◽  
K.W. Schwarz ◽  
S.P. Baker
Keyword(s):  
Cyclic Loading ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Metal Films ◽  
Dislocation Dynamics ◽  
Threading Dislocation ◽  
Dislocation Interactions ◽  
Oriented Films ◽  
Dynamics Simulations ◽  
Fcc Metal

ABSTRACTMesoscopic simulations of dislocation interactions in thin, single crystal FCC metal films were carried out. Interactions between threading-misfit and threading-threading dislocation pairs were studied and the strength of the interactions determined. Threading-threading interactions were found to be significantly stronger than threading-misfit interactions. Dislocations with different possible combinations of Burgers vectors were studied under cyclic loading. Only annihilation of dislocations was seen to result in residual dislocation structure after complete unloading. No differences were observed in the nature of threading-misfit interactions in 111 and 001 oriented films.

scholarly journals Size Dependence of Dislocation-Mediated Plasticity in Ni Single Crystals: Molecular Dynamics Simulations

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Xiaoyan Li ◽  
Wei Yang
Keyword(s):  
Slip System ◽  
Single Crystals ◽  
Temperature Effects ◽  
Size Dependence ◽  
Dislocation Dynamics ◽  
Deformation Mechanisms ◽  
Atomistic Simulations ◽  
Single Slip ◽  
System A ◽  
Dynamics Simulations

We investigate the compressive yielding of Ni single crystals by performing atomistic simulations with the sample diameters in the range of 5 nm ∼ 40 nm. Remarkable effects of sample sizes on the yield strength are observed in the nanopillars with two different orientations. The deformation mechanisms are characterized by massive dislocation activities within a single slip system and a nanoscale deformation twining in an octal slip system. A dislocation dynamics-based model is proposed to interpret the size and temperature effects in single slip-oriented nanopillars by considering the nucleation of incipient dislocations.

Channeling radiation of multi-GeV positrons in single crystals

2016 ◽  
Vol 31 (10) ◽  
pp. 1650051 ◽  
Author(s):  
P. N. Chirkov ◽  
Y. A. Chesnokov ◽  
V. A. Maisheev ◽  
D. Bolognini ◽  
S. Hasan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Single Crystal ◽  
Single Crystals ◽  
Nonlinear Oscillations ◽  
Initial Conditions ◽  
Channeling Radiation ◽  
Comparison With Experimental Data

The process of radiation of 120 GeV positrons moving in a channeling regime in (011) plane of a single crystal was considered. At the beginning on the basis of the theory of nonlinear oscillations, the trajectory of moving positrons at different initial conditions was derived. Then taking into account the nonlinearity of motion, the distribution function over oscillation amplitudes of channeling particles was found. After this, the intensity of radiation at different initial conditions was calculated with the help of two various methods. These results may be useful for comparison with experimental data at positron energies from 100 and more GeV.

scholarly journals PRODUCTION OF HYIGH-PURITY ZINC SINGLE CRYSTALS BY VERTICAL DIRECTED CRYSTALLIZATION METHOD

2020 ◽  
pp. 17-20
Author(s):  
A.P. Shcherban ◽  
G.P. Kovtun ◽  
D.A. Solopikhin ◽  
Yu.V. Gorbenko ◽  
T.Yu. Rudycheva ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
High Purity ◽  
Growth Direction ◽  
Directed Crystallization ◽  
Micro Structure ◽  
Crystalline Perfection ◽  
Impurity Composition ◽  
Crystallization Method

A seedless process has been developed to produce high-purity Zn single crystals by the method of vertical di-rected crystallization from a melt. The output of a single crystal structure is from 60 to 80%. Crystals with different growth directions were obtained: [1015] and [0002]. The deviation angles of the growth direction plane relative to the normal to the axis of the sample are 0.5...6°. Microhardness, crystalline perfection of single crystals and micro-structure have been determined. The impurity composition of the start and end parts of single crystals produced from initial grades of zinc of various purities was studied. The developed process can be used to grow single crystals low-melting metals, such as Cd, Pb, Te, In, Bi, Sn, etc.

Sign in / Sign up

Export Citation Format

Share Document