scholarly journals Rebuilding the Strain Hardening at a Large Strain in Twinned Au Nanowires

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 848 ◽  
Author(s):  
Jiapeng Sun ◽  
Jing Han ◽  
Zhenquan Yang ◽  
Huan Liu ◽  
Dan Song ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Deformation Mechanism ◽  
Strain Softening ◽  
Large Strain ◽  
Dislocation Slip ◽  
Boundary Interaction ◽  
Au Nanowires ◽  
Dynamics Simulations ◽  
Strain Hardening Behavior ◽  
Strength And Ductility

Metallic nanowires usually exhibit ultrahigh strength but low tensile ductility, owing to their limited strain hardening capability. Here, our larger scale molecular dynamics simulations demonstrated that we could rebuild the highly desirable strain hardening behavior at a large strain (0.21 to 0.31) in twinned Au nanowires by changing twin orientation, which strongly contrasts with the strain hardening at the incipient plastic deformation in low stacking-fault energy metals nanowires. Because of this strain hardening, an improved ductility is achieved. With the change of twin orientation, a competing effect between partial dislocation propagation and twin migration is observed in nanowires with slant twin boundaries. When twin migration gains the upper hand, the strain hardening occurs. Otherwise, the strain softening occurs. As the twin orientation increases from 0° to 90°, the dominating deformation mechanism shifts from slip-twin boundary interaction to dislocation slip, twin migration, and slip transmission in sequence. Our work could not only deepen our understanding of the mechanical behavior and deformation mechanism of twinned Au nanowires, but also provide new insights into enhancing the strength and ductility of nanowires by engineering the nanoscale twins.

scholarly journals Atomistic Investigation of Anisotropic Nanoindentation Behavior of Nanotwinned Aluminum Containing Inclined Twin Boundaries

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 695 ◽  
Author(s):  
Yuan Liu ◽  
Yanfeng Duan ◽  
Junjie Zhang
Keyword(s):  
Twin Boundary ◽  
Mechanical Response ◽  
Boundary Migration ◽  
Dislocation Slip ◽  
Twin Boundaries ◽  
Boundary Interaction ◽  
Boundary Orientation ◽  
Superior Mechanical Properties ◽  
Microscopic Deformation ◽  
Dynamics Simulations

Nanotwinned metals exhibit superior mechanical properties due to unique dislocation–twin boundary interactions. In the present work, we elucidate the microscopic deformation mechanisms and their correlations with the macroscopic mechanical response of nanotwinned Al containing inclined twin boundaries under nanoindentation by means of molecular dynamics simulations. The effect of twin boundary orientation with respect to the indented surface on the nanoindentation is evaluated. Simulation results reveal that dislocation slip, dislocation–twin boundary interaction, and twin boundary migration operate in parallel in the plastic deformation of nanotwinned Al. The inclination angle of twin boundaries with respect to indented surface has a strong influence on the interaction between individual deformation modes, which in turn leads to the anisotropic indentation behavior of nanotwinned Al.

Nanostructuring a Zr-Hf Alloy via Large Strain Rolling

2007 ◽  
Vol 539-543 ◽  
pp. 2843-2848 ◽  
Author(s):  
Maria Teresa Pérez-Prado ◽  
F. Salort ◽  
Ling Jiang ◽  
Oscar A. Ruano ◽  
M.E. Kassner
Keyword(s):  
Strain Rate ◽  
Deformation Mechanism ◽  
High Strain ◽  
Large Strain ◽  
Rolling Texture ◽  
Liquid Nitrogen Temperature ◽  
Coarse Grained ◽  
Dislocation Slip ◽  
Ultrafine Grained ◽  
Different Thickness

A coarse grained Zr-Hf alloy has been subjected to one rolling pass with different thickness reductions ranging from 10% to 80%. Rolling was performed at three temperatures: 300°C, room temperature (RT) and liquid nitrogen temperature (-196°C). It has been found that, with increasing strain per pass, i.e., with increasing strain rate, the deformation mechanism changes from twinning to dislocation slip. The minimum strain per pass necessary to trigger the transition in deformation mechanism decreases with decreasing temperature. High strain, high strain-rate deformation leads to the development of an ultrafine grained structure. Simultaneously, a basal type rolling texture forms. At the higher temperatures (RT and above) a recrystallization texture component is also present. Thus, nanostructuring of this Zr-Hf alloy during severe rolling is attributed to a combination of grain subdivision by the formation of geometrically necessary boundaries and to nucleation and growth phenomena taking place as a consequence of rapid adiabatic heating.

Microstructures and Properties of Low-Density High Strength-Toughness Fe-18Mn-9.5Al-0.65C Steel

2015 ◽  
Vol 817 ◽  
pp. 293-298
Author(s):  
Lei Feng Zhang ◽  
Ren Bo Song ◽  
Chao Zhao ◽  
Fu Qiang Yang ◽  
Shuai Qin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Strain Hardening ◽  
Solution Treatment ◽  
Solution Temperature ◽  
Uniform Structure ◽  
Low Density ◽  
Hardening Behavior ◽  
Strain Hardening Behavior ◽  
Strength And Ductility

With excellent mechanical properties and low density, Fe-Mn-Al-C steel would be the first choice for automotive lightweight design in future. In this paper, microstructural evolution, mechanical properties and strain hardening behavior of Fe-18Mn-9.5Al-0.65C steel before and after solution treatment were investigated. The experimental steel had (α+γ) duplex phase structure, density of 6.82g/cm3and high product of strength and ductility. After hot rolling, the steel showed microstructural morphology of austenite matrix and banded ferrite, tensile strength of over 1000MPa and elongation of 25%. During solution treatment, the tensile strength, as well as the yielding strength, decreased with the increase of solution temperature, while the elongation increased first and then decreased sharply for excessively coarsening of grains. After solution treated at 1000°C for 1h, the elongation reached 44%, and product of strength and ductility was 34GPa·%, which was 36% higher than that of the hot-rolled steel. Excellent comprehensive properties are attributed to the multiple-stage strain hardening behavior during tensile deformation, as well as the crush and separation of banded ferrite to form a uniform structure during solution treatment.

Comprehensive study of strain hardening behavior of CrCoNi medium-entropy alloy

2021 ◽  
pp. 160623
Author(s):  
Bo Guan ◽  
Yitao Wang ◽  
Jianbo Li ◽  
Yu Zhang ◽  
Hao Wang ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Hardening Behavior ◽  
Strain Hardening Behavior ◽  
Comprehensive Study
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