Strain rate sensitivity of face-centered-cubic nanocrystalline materials based on dislocation deformation

2006 ◽  
Vol 99 (7) ◽  
pp. 076103 ◽  
Author(s):  
Jianshe Lian ◽  
Changdong Gu ◽  
Qing Jiang ◽  
Zhonghao Jiang
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Nanocrystalline Materials ◽  
Rate Sensitivity ◽  
Face Centered Cubic ◽  
Face Centered

scholarly journals On the Size Effect of Strain Rate Sensitivity and Activation Volume for Face-Centered Cubic Materials: A Scaling Law

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 898
Author(s):  
Xiazi Xiao ◽  
Hao Liu ◽  
Long Yu
Keyword(s):  
Size Effect ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Indentation Depth ◽  
Activation Volume ◽  
Scaling Law ◽  
Rate Sensitivity ◽  
Face Centered Cubic ◽  
Cubic Materials ◽  
Face Centered

In a recent experimental study of indentation creep, the strain rate sensitivity (SRS) and activation volume v* have been noticed to be dependent on the indentation depth or loading force for face-centered cubic materials. Although several possible interpretations have been proposed, the fundamental mechanism is still not well addressed. In this work, a scaling law is proposed for the indentation depth or loading force-dependent SRS. Moreover, v* is indicated to scale with hardness H by the relation ∂ln(v*/b3)/∂lnH=−2 with the Burgers vector b. We show that this size effect of SRS and activation volume can mainly be ascribed to the evolution of geometrically necessary dislocations during the creep process. By comparing the theoretical results with different sets of reported experimental data, the proposed law is verified and a good agreement is achieved.

scholarly journals Twinning-Induced Abnormal Strain Rate Sensitivity and Indentation Creep Behavior in Nanocrystalline Mg Alloy

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7104
Author(s):  
Shilun Yu ◽  
Yingchun Wan ◽  
Chuming Liu ◽  
Zhiyong Chen ◽  
Xiangyang Zhou
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Creep Behavior ◽  
Nanocrystalline Materials ◽  
Volume Fraction ◽  
Chemical Properties ◽  
Rate Sensitivity ◽  
Coarse Grained ◽  
Indentation Creep ◽  
Zr Alloy

Nanocrystalline materials exhibit many unique physical and chemical properties with respect to their coarse-grained counterparts due to the high volume fraction of grain boundaries. Research interests on nanocrystalline materials around the world have been lasting over the past decades. In this study, we explored the room temperature strain rate sensitivity and creep behavior of the nanocrystalline Mg–Gd–Y–Zr alloy by using a nanoindentation technique. Results showed that the hardness and creep displacements of the nanocrystalline Mg–Gd–Y–Zr alloy decreased with increasing loading strain rate. That is, the nanocrystalline Mg–Gd–Y–Zr alloy showed negative strain rate sensitivity and its creep behavior also exhibited negative rate dependence. It was revealed that the enhanced twinning activities at higher loading strain rates resulted in reduced hardness and creep displacements. The dominant creep mechanism of the nanocrystalline Mg–Gd–Y–Zr alloy is discussed based on a work-of-indentation theory in this paper.

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
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