Effects of twin and surface facet on strain-rate sensitivity of gold nanowires at different temperatures

2010 ◽  
Vol 81 (15) ◽  
Author(s):  
Chuang Deng ◽  
Frederic Sansoz
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Gold Nanowires ◽  
Different Temperatures ◽  
Surface Facet

The Influence of Microstructure on Superplastic Behaviours of γ-TiAl Alloys

1998 ◽  
Vol 552 ◽  
Author(s):  
J. Sun ◽  
J. S. Wu ◽  
G. X. Hu ◽  
Y. H. He ◽  
B. Y. Huang
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Maximum Elongation ◽  
Tial Alloys ◽  
Different Temperatures ◽  
Incremental Strain

ABSTRACTIn this work, superplastic behaviours in Ti-33A1–3Cr-0.5Mo (wt%) γ-TiAl alloys with two different initial microstructures of near gamma (NG) and duplex (DM) structure were investigated with respect to the effect of testing temperatures and strain rates. At 1050°C and a strain rate of 8×10–5 S–1, a maximum elongation of 570% was observed for NG-TiAl and a maximum elongation of 467% for DM-TiAl. The relations of flow stress and strain rate sensitivity vs. strain rates at different temperatures were also determined by incremental strain rate tests. The results showed that the value of strain rate sensitivity is higher and the flow stress is lower for NG than those for DM at the same condition. The microstructural evolution during superplastic deformation was examined and correlated to the mechanical properties for these two alloys. The influence of microstructure on the superplastic behaviours of γ-TiAl alloys, and possible superplastic deformation mechanisms were finally discussed.

Strain Rate Sensitivity of Mechanical Properties and Related Thermal Activation Process in a Two-Phase γ Titanium Aluminide

1996 ◽  
Vol 460 ◽  
Author(s):  
Dongliang Lin ◽  
T. L. Lin ◽  
Yu Wang ◽  
Yun Lin ◽  
Young-Won Kim
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Titanium Aluminide ◽  
Thermal Activation ◽  
Rate Sensitivity ◽  
Activation Process ◽  
Two Phase ◽  
Controlling Mechanism ◽  
Activation Theory ◽  
Different Temperatures

ABSTRACTTensile properties of a two-phase γ titanium aluminide with duplex microstructure are tested under different strain rates from 5×10-5 to 5×10-3S-1 at temperature from 1123K to 1273K. It is found that there exists approximate linear relationship between the flow stresses and the logarithm of the strain rate at different temperatures. The strain rate sensitivity can be explained by thermal activation theory, and dislocation climbing is identified as the rate controlling mechanism

Strain Rate Sensitivity of Ultrafine Grained Aluminium Alloy AA6061

2008 ◽  
Vol 584-586 ◽  
pp. 741-747 ◽  
Author(s):  
Aferdita Vevecka-Priftaj ◽  
Andreas Böhner ◽  
Johannes May ◽  
Heinz Werner Höppel ◽  
Matthias Göken
Keyword(s):  
Strain Rate ◽  
Aluminium Alloy ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Grain Structure ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Before And After ◽  
Different Temperatures ◽  
Increasing Temperature

The strain rate sensitivity of the aluminium alloy AA6061 has been investigated in a conventional grain sized (CG) state and in two different ultrafine grained (UFG) conditions processed by Equal Channel Angular Pressing (ECAP) for 2 and 6 passes at 100o C. Strain rate jump tests in compression were performed at different temperatures and the strain-rate sensitivity exponent m was determined. The tests were accomplished by microstructural investigations before and after compression testing in CG and UFG conditions. It is shown that all UFG microstructures exhibit strongly increased strain-rate sensitivity (SRS) compared to the CG state. The SRS increases with increasing temperature and is more pronounced for the UFG material processed using 6 ECAP passes. The microstructural investigations show a rather high stability of the grain structure for the UFG conditions up to 250o C. The results are discussed with respect to the relevant deformation mechanisms.

The Effect of Temperature and Strain-Rate Sensitivity on Formability of AA 5754

2012 ◽  
Vol 217-219 ◽  
pp. 1596-1601 ◽  
Author(s):  
Mevlut Turkoz ◽  
Selcuk Halkacı ◽  
Muammer Koç
Keyword(s):  
Aluminum Alloys ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Effect Of Temperature ◽  
Different Temperatures ◽  
Warm Hydroforming ◽  
Effects Of Temperature ◽  
Different Strains

Aluminum alloys have limited usage because of their limited formability at room temperatures. In order to design and develop more parts made of aluminum, new forming techniques such as hydroforming, warm forming and warm hydroforming have been researched to overcome the low formability issues. This, in turn, necessitates understanding and modeling the behavior of aluminum alloys at different temperatures and strain rates. This paper deals with the investigation of the effect of temperature and strain rate sensitivity on the formability of AA 5754 aluminum alloy. Tensile tests were carried out at temperatures of 20,100,180 and 260°C and forming rates of 25, 100 and 250 mm/min. The mechanical properties and flow curves were obtained and the strain rate sensitivities were calculated at different strains and temperatures. The effects of temperature and strain rate sensitivity on the formability were introduced.

scholarly journals Negative Strain Rate Sensitivity Induced by Structure Heterogeneity in Zr64.13Cu15.75Ni10.12Al10 Bulk Metallic Glass

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 339
Author(s):  
Xiang Wang ◽  
Zhi Qiang Ren ◽  
Wei Xiong ◽  
Si Nan Liu ◽  
Ying Liu ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Strain Rate Sensitivity ◽  
Critical Role ◽  
Rate Sensitivity ◽  
Confined Compression ◽  
Negative Strain Rate Sensitivity ◽  
Cast Specimen ◽  
Structure Heterogeneity

The negative strain rate sensitivity (SRS) of metallic glasses is frequently observed. However, the physical essence involved is still not well understood. In the present work, small-angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM) reveal the strong structure heterogeneity at nanometer and tens of nanometer scales, respectively, in bulk metallic glass (BMG) Zr64.13Cu15.75Ni10.12Al10 subjected to fully confined compression processing. A transition of SRS of stress, from 0.012 in the as-cast specimen to −0.005 in compression processed specimen, was observed through nanoindentation. A qualitative formulation clarifies the critical role of internal stress induced by structural heterogeneity in this transition. It reveals the physical origin of this negative SRS frequently reported in structurally heterogeneous BMG alloys and its composites.

Strain rate sensitivity of a 1.5 GPa nanotwinned steel

2021 ◽  
Author(s):  
R.D. Liu ◽  
Y.Z. Li ◽  
L. Lin ◽  
C.P. Huang ◽  
Z.H. Cao ◽  
...  
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity

scholarly journals The Strain Rate Sensitivity and Creep Behavior for the Tripler Plane of Potassium Dihydrogen Phosphate Crystal by Nanoindentation

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 369
Author(s):  
Jianhui Mao ◽  
Wenjun Liu ◽  
Dongfang Li ◽  
Chenkai Zhang ◽  
Yi Ma
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Creep Deformation ◽  
Potassium Dihydrogen Phosphate ◽  
Rate Sensitivity ◽  
Dislocation Nucleation ◽  
Machining Process ◽  
Dihydrogen Phosphate ◽  
Potassium Dihydrogen ◽  
Kdp Crystals

As an excellent multifunctional single crystal, potassium dihydrogen phosphate (KDP) is a well-known, difficult-to-process material for its soft-brittle and deliquescent nature. The surface mechanical properties are critical to the machining process; however, the characteristics of deformation behavior for KDP crystals have not been well studied. In this work, the strain rate effect on hardness was investigated on the mechanically polished tripler plane of a KDP crystal relying on nanoindentation technology. By increasing the strain rate from 0.001 to 0.1 s−1, hardness increased from 1.67 to 2.07 GPa. Hence, the strain rate sensitivity was determined as 0.053, and the activation volume of dislocation nucleation was 169 Å3. Based on the constant load-holding method, creep deformation was studied at various holding depths at room temperature. Under the spherical tip, creep deformation could be greatly enhanced with increasing holding depth, which was mainly due to the enlarged holding strain. Under the self-similar Berkovich indenter, creep strain could be reduced at a deeper location. Such an indentation size effect on creep deformation was firstly reported for KDP crystals. The strain rate sensitivity of the steady-state creep flow was estimated, and the creep mechanism was qualitatively discussed.

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