An Atomistic Study on the Slip Deformation Mechanism of Crystalline Materials Using a Weak-Plane Model

2012 ◽  
Vol 197 ◽  
pp. 321-326 ◽  
Author(s):  
Takuya Uehara
Keyword(s):  
Plastic Deformation ◽  
Deformation Mechanism ◽  
Tensile Load ◽  
Longitudinal Direction ◽  
Crystalline Materials ◽  
Step Motion ◽  
Weak Plane ◽  
Dynamics Simulations ◽  
Atomistic Study ◽  
Deformation Modes

Molecular dynamics simulations were carried out to investigate the plastic deformation mechanism of fcc crystalline materials using the conventional Lennard-Jones potential. An fcc structure with square cross-section was prepared, and a tensile load was applied in the longitudinal direction. A weak potential was assigned to a specific (111) plane to induce a slip on the specified plane. Accordingly, a slip was initiated in the weak plane following an elastic deformation. The step-by-step motion of the atoms on the slip plane was studied, and a detailed trajectory is presented. The slip then expanded to other planes, and plastic deformation progressed in the whole model. The weak plane was also set as (110) or (100) plane, where different deformation modes were observed: not only slip but also gradual distortion or brittle fracture occurred.

Effect of Strain Amounts on Cold Compression Deformation Mechanism of Ti-55531 Alloy with Bimodal Microstructure

2021 ◽  
Vol 1035 ◽  
pp. 182-188
Author(s):  
Jian Hua Cai ◽  
She Wei Xin ◽  
Lei Li ◽  
Lei Zou ◽  
Hai Ying Yang ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Deformation Mechanism ◽  
True Strain ◽  
Bimodal Microstructure ◽  
Free Zone ◽  
Β Phase ◽  
Α Phase ◽  
Initial Stage ◽  
Pile Up ◽  
Dislocation Tangle

The plastic deformation mechanism of Ti-55531 alloy with bimodal microstructure was investigated by compression testing at room temperature. The bimodal microstructure was composed of equiaxed primary α phase (αp) and transformed β (βtrans) that consisted of acicular secondary α phase (αs) and residual β phase (βr). In the initial stage of deformation, the αp grains first underwent plastic deformation, the dislocations germinated and increased, forming the dislocation loop with the dislocation free zone in αp at the true stain of 0.083. With the true strain subsequently increasing to 0.105, the dislocation tangle and dislocation pile-up occurred in αp, and a lot of dislocations were also activated in most of αs. Moreover, the dislocation density was increasing gradually in βr with the adding of strain. Finally, the dislocation pile-up and dislocation tangle appeared in αs and βr at the true strain of 0.163. The whole deformation process was coordinated by αp, αs and βr. They accommodated mutually and completed deformation together.

Short-Term Oxidation Behavior, Microstructure Evolution and Compression Behavior of Nickel-Based Superalloy GH4037 in Solid and Semi-Solid States

2022 ◽  
Vol 327 ◽  
pp. 11-25
Author(s):  
Guan Fei Xiao ◽  
Ju Fu Jiang ◽  
Ying Wang ◽  
Ying Zhe Liu ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Deformation Mechanism ◽  
Deformation Zone ◽  
Solid Particles ◽  
Isothermal Treatment ◽  
Short Term ◽  
Solid States ◽  
Nickel Based Superalloy ◽  
Semi Solid ◽  
Solid Temperature

Semi-solid processing combines the advantages of traditional forging and casting methods, so it has received much attention recently. However, the research on semi-solid behaviors of Nickel-based superalloys has been rarely reported. In order to investigate the behaviors of Nickel-based superalloy at solid and semi-solid states, oxidation experiments, isothermal treatment experiments and deformation experiments of GH4037 alloy were studied. Short-term oxidation experiments of GH4037 alloy were carried out at a solid temperature (1200 °C) and a semi-solid temperature (1360 °C). The results indicated that the oxides formed at 1200 °C were mainly composed of TiO2, Cr2O3 and a small amount of spinels NiCr2O4, while the oxides formed at 1360 °C consisted of the spinels of NiCr2O4, NiWO4 and NiMoO4 besides TiO2 and Cr2O3. Microstructure evolution of GH4037 alloy after semi-solid isothermal treatment at 1370 °C and 1380 °C was studied. The results indicated that semi-solid microstructures consisted of equiaxed solid grains and liquid phases. The average grains size and shape factor of solid grains were affected by melting mechanism and grain growth mechanism. Compression behaviors of GH4037 alloy after compressed at 1200 °C and 1360 °C were investigated. The results indicated that the flow stress of 1360 °C decreased significantly compared to that of 1200 °C. The deformation zones in the specimens were divided into three parts: the difficult deformation zone, the large deformation zone, and the free deformation zone. At 1200 °C, the deformation mechanism was plastic deformation mechanism. At 1360 °C, sliding between solid particles (SS), liquid flow (LF), flow of liquid incorporating solid particles (FLS), plastic deformation of solid particles (PDS) coexisted in the compression specimen.

scholarly journals Ultrafast calculation of diffuse scattering from atomistic models

2019 ◽  
Vol 75 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Joseph A. M. Paddison
Keyword(s):  
Diffuse Scattering ◽  
Large Data ◽  
Large Data Sets ◽  
Scattering Data ◽  
Frequency Noise ◽  
Data Sets ◽  
Fast Method ◽  
Crystalline Materials ◽  
Atomistic Models ◽  
Dynamics Simulations

Diffuse scattering is a rich source of information about disorder in crystalline materials, which can be modelled using atomistic techniques such as Monte Carlo and molecular dynamics simulations. Modern X-ray and neutron scattering instruments can rapidly measure large volumes of diffuse-scattering data. Unfortunately, current algorithms for atomistic diffuse-scattering calculations are too slow to model large data sets completely, because the fast Fourier transform (FFT) algorithm has long been considered unsuitable for such calculations [Butler & Welberry (1992). J. Appl. Cryst. 25, 391–399]. Here, a new approach is presented for ultrafast calculation of atomistic diffuse-scattering patterns. It is shown that the FFT can actually be used to perform such calculations rapidly, and that a fast method based on sampling theory can be used to reduce high-frequency noise in the calculations. These algorithms are benchmarked using realistic examples of compositional, magnetic and displacive disorder. They accelerate the calculations by a factor of at least 102, making refinement of atomistic models to large diffuse-scattering volumes practical.

scholarly journals Atomistic study of plastic deformation in Mg–Al alloys

2013 ◽  
Vol 586 ◽  
pp. 245-252 ◽  
Author(s):  
Wei Xiao ◽  
Xu Zhang ◽  
Wen Tong Geng ◽  
Gang Lu
Keyword(s):  
Plastic Deformation ◽  
Al Alloys ◽  
Atomistic Study
Sign in / Sign up

Export Citation Format

Share Document