ENHANCED TENSILE DUCTILITY IN AN ELECTRODEPOSITED CU WITH NANO-SIZED GROWTH TWINS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2537-2542 ◽  
Author(s):  
GUOYONG WANG ◽  
ZHONGHAO JIANG ◽  
JIANSHE LIAN
Keyword(s):  
Strain Rate ◽  
Activation Volume ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Dislocation Motion ◽  
Lamellar Thickness ◽  
Petch Relation ◽  
Transmission Electron ◽  
Mean Size ◽  
Dislocation Process

A fully dense electrodeposited microcrystalline copper with nano-scale twins was synthesized by electrodeposition. The microstructure of this copper was analyzed X-ray diffractometer (XRD) and by transmission electron microscopy (TEM). The grains of mean size about 2mm were divided by high density of growth twins with mean lamellar thickness of about 90 nm. Tensile tests at different strain rates and room temperature showed that the strength increased from 379 MPa to 458 MPa with strain rate increasing from 10-5 s-1 to 0.1 s-1. The elongations to fracture were in the range of 13.6~15.5%. So this Cu has good combination of strength and ductility. The strengths are much higher than that determined by Hall-Petch relation with the same grain size, which means that twin boundaries are effective in blocking dislocation motion. The strain rate sensitivity and activation volume estimated from the flow stress versus strain curves was 0.016 and 84 b3~69b3, respectively. Such a large activation volume indicates that the deformation of this copper was controlled by dislocation process.

Multilevel Analysis of Strain Rate Effect on Visco-Damage Evolution in Short Random Fiber Reinforced Polymer Composites

2021 ◽  
Vol 36 (2) ◽  
pp. 213-218
Author(s):  
M. D. D. Boudiaf ◽  
L. Hemmouche ◽  
M. A. Louar ◽  
A. May ◽  
N. Mesrati
Keyword(s):  
Strain Rate ◽  
Damage Evolution ◽  
Glass Fibers ◽  
Rate Sensitivity ◽  
Polymeric Composite ◽  
Tensile Tests ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Fiber Reinforced ◽  
Stress Levels

Abstract In this study, the strain rate sensitivity of a discontinuous short fiber reinforced composite and the strain rate effect on the damage evolution are investigated. The studied material is a polymeric composite with a polyamide 6.6 matrix reinforced with oriented randomly short glass fibers at a 50% weigh ratio (PA6.6GF50). Tensile tests at low and high strain rate are conducted. In addition, interrupted tensile tests are carried out to quantify the damage at specific stress levels and strain rates. To perform the interrupted tensile tests, an intermediate fixture is realized via double notched mechanical fuses with different widths designed to break at suitable stress levels. The damage is estimated by the fraction of debonded fibers and matrix fractures. Based on the experimental observations, it is concluded that the ultimate stress and strain, and the damage threshold are mainly governed by the strain rate. Furthermore, it is established that the considered composite has a non-linear dynamic behavior with a viscous damage nature.

Superplastic Behavior of a Cu-Cr-Zr Alloy Subjected to ECAP

2016 ◽  
Vol 838-839 ◽  
pp. 404-409
Author(s):  
Roman Mishnev ◽  
Iaroslava Shakhova ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Strain Rate ◽  
Temperature Interval ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Superplastic Behavior ◽  
Average Grain Size ◽  
Gauge Section ◽  
Zr Alloy

A Cu-0.87%Cr-0.06%Zr alloy was subjected to equal channel angular pressing (ECAP) at a temperature of 400 °C up to a total strain of ~ 12. This processing produced ultra-fine grained (UFG) structure with an average grain size of 0.6 μm and an average dislocation density of ~4×1014 m-2. Tensile tests were carried out in the temperature interval 450 – 650 °C at strain rates ranging from 2.8´10-4 to 0.55 s-1. The alloy exhibits superplastic behavior in the temperature interval 550 – 600 °C at strain rate over 5.5´10-3 s-1. The highest elongation-to-failure of ~300% was obtained at a temperature of 575 °C and a strain rate of 2.8´10-3 s-1 with the corresponding strain rate sensitivity of 0.32. It was shown the superplastic flow at the optimum conditions leads to limited grain growth in the gauge section. The grain size increases from 0.6 μm to 0.87 μm after testing, while dislocation density decreases insignificantly to ~1014 m-2.

Plastic Flow Instabilities of L12 Ni3(Si,Ti) Alloys at Intermediate Temperature

2002 ◽  
Vol 17 (3) ◽  
pp. 705-711 ◽  
Author(s):  
H. Honjo ◽  
Y. Kaneno ◽  
H. Inoue ◽  
T. Takasugi
Keyword(s):  
Strain Rate ◽  
Plastic Flow ◽  
Flow Behavior ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Lattice Diffusion ◽  
Intermediate Temperature ◽  
Fine Grained ◽  
Ti Alloys ◽  
Temperature Strain

The serrated plastic flow of L12 Ni3 (Si,Ti) alloys at intermediate temperature was investigated by tensile tests in terms of the effects of temperature, strain rate, composition, and microstructure. Serrated plastic flow was most strongly observed at 473 K and at a strain rate of 1.6 × 10–4 s–1. Correspondingly, the maximum stress amplitude and the lowest (negative) strain-rate sensitivity were observed at 473 K. Serrated plastic flow took place irrespective of boron doping and was more significant in a fine-grained Ni3 (Si,Ti) alloy. The static aging at 473 K resulted in reduced flow stress. The activation energy for serrated plastic flow was estimated to be about 57 kJ mol–1, suggestive of being smaller than that for lattice diffusion of solutes. The serrated plastic flow behavior of Ni3 (Si,Ti) alloys was compared with that of L12 Co3Ti alloys, and is qualitatively explained on the basis of the dynamics of solutes in the core of a dissociated screw dislocation.

Study on the Super-Plastic Property of ECAPed Magmesium Alloy

2011 ◽  
Vol 311-313 ◽  
pp. 640-643
Author(s):  
Ying Jie Li ◽  
Xiu Zhi Zhang ◽  
Feng Li
Keyword(s):  
Grain Boundary ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Plastic Property ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Flow Activation Energy ◽  
Super Plastic ◽  
Deformation Behaviors ◽  
Lower Temperature

In this paper, the influence of temperature and strain rate on the superplastic deformation behaviors of the Mg-Zn-Nd alloy has been investigated through performing tensile tests at different temperatures and strain rates. After 4 passes of ECAP by route C, the strain-rate sensitivity coefficients reached 0.32 at 300°C, indicating that the ECAPed Mg-Zn-Nd alloy exhibited a good superplasticity at lower temperature. The results of flow activation energy showed that the super-plastic deformation mechanism of magnesium alloys is grain-boundary sliding controlled by grain boundary diffusion.

Activation volume and strain rate sensitivity in plastic deformation of nanocrystalline Ti

2013 ◽  
Vol 228 ◽  
pp. S254-S256 ◽  
Author(s):  
F. Wang ◽  
B. Li ◽  
T.T. Gao ◽  
P. Huang ◽  
K.W. Xu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Activation Volume ◽  
Rate Sensitivity

Modeling of the Plastic Characteristics of AA6082 for the Friction Stir Welding Process

2015 ◽  
Vol 639 ◽  
pp. 309-316
Author(s):  
Sergio Pellegrino ◽  
Livan Fratini ◽  
Marion Merklein ◽  
Wolfgang Böhm ◽  
Hung Nguyen
Keyword(s):  
Friction Stir Welding ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Flow Behavior ◽  
Welding Process ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Friction Stir ◽  
Friction Stir Welding Process ◽  
Welding Processes

Focus of this paper is to model the plastic forming behavior of AA6082, in order to develop the numerical FE analysis of the friction stir welding processes and the simulation of subsequent forming processes. During the friction stir welding process, the temperatures reached are until 500 °C and have a fundamental role for the correct performance of the process so the material data has to show a temperature dependency. Because of the tool rotation a strain rate sensitivity of the material has to be respected as well. In this context, the general material characteristics of AA6082 were first identified for different stress states. For the uniaxial state the standard PuD-Al used in the automotive industry was applied, for the shear state the ASTM B831-05 was used and for biaxial states the ISO 16842 was exploited. To characterize the plastic flow behavior of the AA6082 at elevated temperatures tensile tests were performed according to DIN EN ISO 6892-2 from 25 °C until 500 °C with a strain rate from 0.1 s-1up to 6.5 s-1.

Practical Design of Ni3Al with High Hot Workability

1996 ◽  
Vol 460 ◽  
Author(s):  
Yinmin Wang ◽  
Dongliang Lin ◽  
Yun Zhang
Keyword(s):  
Strain Rate ◽  
Compressive Strain ◽  
Tensile Tests ◽  
Rolling Process ◽  
Strain Rates ◽  
Hot Workability ◽  
Transmission Electron ◽  
Cr Addition ◽  
Hot Rolled ◽  
Compressive Tests

ABSTRACTFrom our previous work, Ni3Al polycrystals with combined addition of magnesium and silicon kept high values of compressive strain at rupture (CSR) when the strain rate rose. In order to further improve hot workability of Ni3Al, 7.9wt.% Cr was added. The compressive tests showed that 30%∼40% CSR values of the alloy had been kept in a wide temperature range of 1173K-1373K at strain rates of 10-2sec-1 and 10-2sec-1 in contrast with 15%∼25% CSR values of the alloy without Cr addition.In practical hot rolling process, at initial deformation temperature of 1373K, strain rate of 1.0 sec-1 and by controlling reduction within 10∼15% each rolling pass, Ni3Al ingots were successfully hot-rolled into polycrystals with different deformations, the maximum of which was 55%. The deformed alloys had manifestly enhanced mechanical properties shown by tensile tests.The dislocation configurations of deformed alloys have been investigated by using transmission electron microscope(TEM).

Strain-Rate Sensitivity of Concrete: Influence of Moisture Content

2006 ◽  
Vol 326-328 ◽  
pp. 1661-1664
Author(s):  
Gao Lin ◽  
Dong Ming Yan
Keyword(s):  
Moisture Content ◽  
Strain Rate ◽  
Earthquake Engineering ◽  
Testing Machine ◽  
Dynamic Strength ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Hydraulic Testing ◽  
Wide Range ◽  
Compressive Tests

Understanding the behavior of concrete under dynamic loading conditions is an issue of great significance in earthquake engineering. Moisture content has an important influence on the strain-rate effect of concrete. In this study, both tensile and compressive experiments were carried out to investigate the rate-dependent behavior of concrete. Tensile experiments of dumbbell-shaped specimens were conducted on a MTS810 testing machine and compressive tests of cubic specimens were performed on a servo-hydraulic testing machine designed and manufactured at Dalian University of Technology, China. The strain rate varied in a wide range. The analytical formulations between the dynamic strength and strain rate were proposed for both compressive tests and tensile tests. It was concluded from the results that with the increasing strain rate, strengths of specimens with both moisture contents tended to increase and the increase seemed to be more remarkable for the saturated specimens; based on the experimental observation, a better explanation for the dynamic behavior is presented.

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