(Invited) Heteroepitaxial Lattice Mismatch Stress Relaxation in Nonpolar and Semipolar GaN by Dislocation Glide

2013 ◽  
Vol 50 (9) ◽  
pp. 797-800
Author(s):  
E. C. Young ◽  
J. S. Speck
Keyword(s):  
Stress Relaxation ◽  
Lattice Mismatch ◽  
Dislocation Glide ◽  
Mismatch Stress ◽  
Semipolar Gan

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.

Mechanisms of Inelastic Deformation and Stress Relaxation in Thin Metallizations Bonded to Hard Substrates

1991 ◽  
Vol 226 ◽  
Author(s):  
M.A. Korhonen ◽  
P. Bergesen ◽  
Che-Yu Li
Keyword(s):  
Thin Films ◽  
Stress Relaxation ◽  
Integrated Circuits ◽  
Large Scale ◽  
Effective Means ◽  
Grain Boundary Sliding ◽  
Dislocation Creep ◽  
Dislocation Glide ◽  
Constrained Deformation ◽  
Hard Substrates

AbstractThe yield strength of metallic thin films bonded to hard substrates can be significantly higher than is customary for bulk samples of the same metal. This is related to the constrained nature of the deformation. The constrained deformation, as well as the commonly observed crystallographic texture of thin films, places restrictive conditions on the mechanisms of deformation that produce stress relaxation. In narrow aluminum based metallizations used as interconnects in large scale integrated circuits thermal stress induced voiding provides an effective means for stress relaxation. For these interconnects, the stress state is tensile after excursions to higher temperatures; the stresses relax mainly by dislocation glide and grain boundary sliding during the cooldown, while the longer term relaxation is governed by stress-induced voiding and dislocation creep.

Evidence for the lattice-mismatch-stress-field induced flux pinning in (Gd1 − xYx)BA2Cu3O7 − σ thin films

1996 ◽  
Vol 262 (1-2) ◽  
pp. 81-88 ◽  
Author(s):  
H.H. Wen ◽  
Z.X. Zhao ◽  
R.L. Wang ◽  
H.C. Li ◽  
B. Yin
Keyword(s):  
Thin Films ◽  
Stress Field ◽  
Flux Pinning ◽  
Lattice Mismatch ◽  
Mismatch Stress

The Strain Rate Sensitivity of Ni3(Al,Ta) Single Crystals.

1990 ◽  
Vol 213 ◽  
Author(s):  
J. Bonneville ◽  
J.L. Martin
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Single Crystals ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Complete Information ◽  
Dislocation Glide ◽  
Plastic Deformation Process ◽  
Nonmonotonic Variation ◽  
Almost All

ABSTRACTIn order to obtain more complete information about the strain rate sensitivity of the flow stress of L12 alloys, Ni3Al,Ta) single crystals have been deformed in compression, over a range of temperatures (293–1273K), at two different strain rates and in stress relaxation experiments.During the stress relaxation tests, at almost all the temperatures (except T~470K), a logarithmic decrease of the stress as a function of time has been observed. This is in fair agreement with the classical frame work of the thermal activation theory of dislocation glide. Thus, the corresponding apparent activation volumes have been determined and the nonmonotonic variation of this activation parameter with the temperature indicates that it is necessary to consider more than one plastic deformation process. These new results are discussed in terms of the previously published models which account for the plastic behaviours of the L12 compounds.

Mechanisms of Inelastic Deformation and Stress Relaxation in Thin Metallizations Bonded to Hard Substrates

1991 ◽  
Vol 225 ◽  
Author(s):  
M. A. Korhonen ◽  
P. Brørgesen ◽  
Che-Yu Li
Keyword(s):  
Thin Films ◽  
Stress Relaxation ◽  
Integrated Circuits ◽  
Large Scale ◽  
Effective Means ◽  
Grain Boundary Sliding ◽  
Dislocation Creep ◽  
Dislocation Glide ◽  
Constrained Deformation ◽  
Hard Substrates

ABSTRACTThe yield strength of metallic thin films bonded to hard substrates can be significantly higher than is customary for bulk samples of the same metal. This is related to the constrained nature of the deformation. The constrained deformation, as well as the commonly observed crystallographic texture of thin films, places restrictive conditions on the mechanisms of deformation that produce stress relaxation. In narrow aluminum based metallizations used as interconnects in large scale integrated circuits thermal stress induced voiding provides an effective means for stress relaxation. For these interconnects, the stress state is tensile after excursions to higher temperatures; the stresses relax mainly by dislocation glide and grain boundary sliding during the cooldown, while the longer term relaxation is governed by stress-induced voiding and dislocation creep.

Enhanced stress relaxation of Sn–3.8Ag–0.7Cu solder by electrical current

2010 ◽  
Vol 25 (6) ◽  
pp. 1172-1178 ◽  
Author(s):  
Haiyan Liu ◽  
Qingsheng Zhu ◽  
Li Zhang ◽  
Zhongguang Wang ◽  
Jian Ku Shang
Keyword(s):  
Stress Relaxation ◽  
Relaxation Rate ◽  
Solder Joints ◽  
Vacancy Concentration ◽  
Electrical Current ◽  
Current Application ◽  
Electrical Currents ◽  
Dislocation Glide ◽  
Reliability Of Solder Joints ◽  
Relaxation Responses

The stress relaxation responses of the Sn–3.8Ag–0.7Cu joints following exposure to electrical currents were examined to investigate the effect of electromigration on the reliability of solder joints. It was found that the stress relaxation rate was enhanced for the Sn–3.8Ag–0.7Cu solder joints subjected to a current density of 2 × 104 A/cm2. Sn hillock formation was observed in situ on the surface of the solder joint and the increase of the hillock volume was obtained as a function of the current application time. Analysis of the vacancy flux indicated that the variations of the vacancy concentration with the electromigration time from the calculations agreed with the growth kinetics of the hillocks observed in the experiments. By modeling the stress relaxation as a climb-assisted dislocation glide process, it is shown that the vacancy accumulation induced by electromigration enhanced the dislocation climb rate, resulting in a large increase of the stress relaxation rate.

Stress Relaxation in Al-Si-Cu Thin Films and Lines

1994 ◽  
Vol 356 ◽  
Author(s):  
A. Witvrouw ◽  
J. Proost ◽  
B. Deweerdt ◽  
Ph. Roussel ◽  
K. Maex
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Flow Stress ◽  
Stress Relaxation ◽  
Relaxation Data ◽  
Cu Films ◽  
Dislocation Glide ◽  
Average Activation Energy ◽  
Curvature Measurements ◽  
Substrate Curvature

AbstractSubstrate curvature measurements were used to study stress relaxation in Al-Si-Cu films at temperatures between 45 and 165 °C. Dislocation glide with an average activation energy, resp. athermal flow stress of 1.7 ± 0.2 eV, resp. 600 ± 200 MPa could describe the relaxation data for temperatures up to 120 °C well. Stress relaxation at 92 °C was found to progress much slower in 1 μm wide nitride passivated lines than in thin films or unpassivated lines.

scholarly journals Nanoscale precipitates as sustainable dislocation sources for enhanced ductility and high strength

2020 ◽  
Vol 117 (10) ◽  
pp. 5204-5209 ◽  
Author(s):  
Shenyou Peng ◽  
Yujie Wei ◽  
Huajian Gao
Keyword(s):  
Lattice Mismatch ◽  
High Stress ◽  
High Strength ◽  
Material Design ◽  
Dislocation Nucleation ◽  
Precipitate Size ◽  
Unique Type ◽  
Dislocation Glide ◽  
High Stress Concentration ◽  
Dislocation Sources

Traditionally, precipitates in a material are thought to serve as obstacles to dislocation glide and cause hardening of the material. This conventional wisdom, however, fails to explain recent discoveries of ultrahigh-strength and large-ductility materials with a high density of nanoscale precipitates, as obstacles to dislocation glide often lead to high stress concentration and even microcracks, a cause of progressive strain localization and the origin of the strength–ductility conflict. Here we reveal that nanoprecipitates provide a unique type of sustainable dislocation sources at sufficiently high stress, and that a dense dispersion of nanoprecipitates simultaneously serve as dislocation sources and obstacles, leading to a sustainable and self-hardening deformation mechanism for enhanced ductility and high strength. The condition to achieve sustainable dislocation nucleation from a nanoprecipitate is governed by the lattice mismatch between the precipitate and matrix, with stress comparable to the recently reported high strength in metals with large amount of nanoscale precipitates. It is also shown that the combination of Orowan’s precipitate hardening model and our critical condition for dislocation nucleation at a nanoprecipitate immediately provides a criterion to select precipitate size and spacing in material design. The findings reported here thus may help establish a foundation for strength–ductility optimization through densely dispersed nanoprecipitates in multiple-element alloy systems.

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