scholarly journals Size effects in polycrystalline thin films analyzed by discrete dislocation plasticity

2005 ◽  
Vol 479 (1-2) ◽  
pp. 329-338 ◽  
Author(s):  
Lucia Nicola ◽  
Erik Van der Giessen ◽  
Alan Needleman
Keyword(s):  
Thin Films ◽  
Size Effects ◽  
Polycrystalline Thin Films ◽  
Discrete Dislocation ◽  
Dislocation Plasticity

Plasticity in Polycrystalline Thin Films: a 2D Dislocation Dynamics Approach

2003 ◽  
Vol 779 ◽  
Author(s):  
Lucia Nicola ◽  
Erik Van der Giessen ◽  
Alan Needleman
Keyword(s):  
Thin Films ◽  
Dislocation Dynamics ◽  
Stress Evolution ◽  
Polycrystalline Thin Films ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Strain Formulation ◽  
The Difference ◽  
Film Substrate ◽  
Edge Dislocations

AbstractThermal stress evolution in polycrystalline thin films is analyzed using discrete dislocation plasticity. Stress develops in the film during cooling from a stress-free configuration due to the difference in thermal expansion coefficient between the film and its substrate. A plane strain formulation with only edge dislocations is used and each grain of the polycrystal has a specified set of slip systems. The film–substrate interface and the grain boundaries are impenetrable for the dislocations. Results are presented for two film thicknesses, with higher hardening seen for the thinner films.

A coupled atomistics and discrete dislocation plasticity simulation of nanoindentation into single crystal thin films

2004 ◽  
Vol 52 (2) ◽  
pp. 271-284 ◽  
Author(s):  
Ronald E Miller ◽  
L.E Shilkrot ◽  
William A Curtin
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Discrete Dislocation ◽  
Dislocation Plasticity

scholarly journals Discrete dislocation analysis of size effects in thin films

2003 ◽  
Vol 93 (10) ◽  
pp. 5920-5928 ◽  
Author(s):  
Lucia Nicola ◽  
Erik Van der Giessen ◽  
Alan Needleman
Keyword(s):  
Thin Films ◽  
Size Effects ◽  
Discrete Dislocation

Cyclic Bending Response of Single- and Polycrystalline Thin Films: Two Dimensional Discrete Dislocation Dynamics

2013 ◽  
Vol 275-277 ◽  
pp. 132-137 ◽  
Author(s):  
Hai Dong Fan ◽  
Qing Yuan Wang ◽  
Muhammad Kashif Khan
Keyword(s):  
Thin Films ◽  
Interaction Model ◽  
Cyclic Hardening ◽  
Dislocation Dynamics ◽  
Two Dimensional ◽  
Cyclic Bending ◽  
Discrete Dislocation Dynamics ◽  
Polycrystalline Thin Films ◽  
Discrete Dislocation ◽  
Bending Response

The bending behavior of single- and polycrystalline thin films is modeled by two-dimensional discrete dislocation dynamics (DDD) to study the cyclic bending response. In the polycrystalline films, grain boundaries (GBs) are simulated with a penetrable dislocation-GB interaction model. Our results reveal that the single- and polycrystalline thin films under pure bending exhibit strong Bauschinger effect but no cyclic hardening or softening. Furthermore, the uploading response of each cycle can be divided into three stages, which are associated with the glide, annihilation and nucleation of dislocations, respectively.

Electron diffraction studies of amorphous and polycrystalline thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 118-119
Author(s):  
D J H Cockayne ◽  
D R McKenzie
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Polycrystalline Materials ◽  
Good Resolution ◽  
Scattered Intensity ◽  
Radial Density ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Nitrogen Ion ◽  
Diffraction Patterns

The study of amorphous and polycrystalline materials by obtaining radial density functions G(r) from X-ray or neutron diffraction patterns is a well-developed technique. We have developed a method for carrying out the same technique using electron diffraction in a standard TEM. It has the advantage that studies can be made of thin films, and on regions of specimen too small for X-ray and neutron studies. As well, it can be used to obtain nearest neighbour distances and coordination numbers from the same region of specimen from which HREM, EDS and EELS data is obtained.The reduction of the scattered intensity I(s) (s = 2sinθ/λ ) to the radial density function, G(r), assumes single and elastic scattering. For good resolution in r, data must be collected to high s. Previous work in this field includes pioneering experiments by Grigson and by Graczyk and Moss. In our work, the electron diffraction pattern from an amorphous or polycrystalline thin film is scanned across the entrance aperture to a PEELS fitted to a conventional TEM, using a ramp applied to the post specimen scan coils. The elastically scattered intensity I(s) is obtained by selecting the elastically scattered electrons with the PEELS, and collecting directly into the MCA. Figure 1 shows examples of I(s) collected from two thin ZrN films, one polycrystalline and one amorphous, prepared by evaporation while under nitrogen ion bombardment.

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