Deformation and machining mechanism of nanocrystalline NiCoCrFe high entropy alloys

Bui, Thi-Xuyen; Fang, Te‐Hua; Lee, Chun‐I

doi:10.1016/j.jallcom.2022.166525

Cited by 18 publications

(8 citation statements)

References 92 publications

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“…The results of Cu substrate damage confirmed that the HEA coating could effectively enhance the wear resistance of the material surface [13]. Bui et al demonstrated that the dislocations in nanocrystalline NiCoCrFe HEAs increase with increasing Fe composition or Co composition, leading to a decrease in cutting process efficiency or a reduction of the number of atoms worn out [14].…”

Section: Introductionmentioning

confidence: 81%

“…The von Mises stress distribution is most pronounced for grain refinement samples of 1.50-4.03 nm because of the largest grain boundary area, as shown in figure 4(b 1 ). GB is the weakest region that generates the compound stress distribution to enlarge the amorphous region [14,46]. The anisotropy of the grains leads to anisotropic deformation and increases the surface indentation density, which is another reason.…”

Section: The Influence Of Grain Refinement Gradientmentioning

confidence: 99%

“…The anisotropy of the grains leads to anisotropic deformation and increases the surface indentation density, which is another reason. Therefore, the stresses required to promote plastic deformation are higher at the GB than inside the grains [14,47].…”

Section: The Influence Of Grain Refinement Gradientmentioning

confidence: 99%

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Effects of grain boundary and gradient structure on machining property of CoCrFeMnNi alloys

Lu,

Bui,

Fang

2024

Modelling Simul. Mater. Sci. Eng.

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CoCrFeMnNi high-entropy alloy (HEA) has a high degree of thermodynamic stability and excellent ductility, making it a crucial structural material. However, the plastic deformation and microstructural behavior of gradient grain structured CoCrFeMnNi HEA under cutting remain unclear. In this study, the machining properties of gradient nanostructured CoCrFeMnNi HEA under conventional cutting were investigated by molecular dynamics (MD) simulation. The results displayed that the small grain gradient samples exhibited grain size softening. The shear angle and cutting ratio increased with the increase in the grain gradient. The grain boundaries of the low grain gradient samples were damaged and slid during the cutting process. Moreover, the dislocation density increased with the increasing grain gradient. The multi-dislocation nodes and the Lomer-Cottrell junction were produced in the grain coarsening gradient samples, contributing to work hardening. The cutting forces from low to high cutting velocities were 136.70, 147.91, 165.82, and 164.79 nN, which confirmed that the cutting forces increased with increased cutting velocity. This work elucidated the cutting mechanism of the nanostructured CoCrFeMnNi HEA and highlighted the influence of the gradient grain sizes.

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Section: Introductionmentioning

confidence: 81%

Section: The Influence Of Grain Refinement Gradientmentioning

confidence: 99%

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Effects of grain boundary and gradient structure on machining property of CoCrFeMnNi alloys

Lu,

Bui,

Fang

2024

Modelling Simul. Mater. Sci. Eng.

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“…The heat flux  ( ) q W m x 2 represents the thermal conductivity per unit area of the vertical heat transfer direction in the x direction, which is proportional to the gradient of the x direction dT/dx, A is the heat transfer intercept of the material area, k is the heat transfer property of the material, and the negative sign indicates that heat must be transferred from high temperature to low temperature. The temperature at each segment is calculated by following equation (5) [63][64][65].…”

Section: Methodologiesmentioning

confidence: 99%

Mechanical characteristics and thermal conductivity of defect single-layer buckled honeycomb germanene

Tseng,

Bui,

et al. 2024

Phys. Scr.

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This study uses molecular dynamics (MD) simulation to investigate the defect rate, defect morphology, and different temperature effects on the mechanical properties, deformation behavior, and thermal conductivities of a single layer of germanene nanosheets via a tensile process.Samples are squeezed in the middle, leading to filling in minor defects. Young's modulus and yield strength decrease with increasing temperature and defect rates. Young's modulus in the armchair direction is larger than that in the zigzag direction, with the samples with a random porosity of 0 %and 2 % and smaller than the model with a random porosity of 4 % to 10 %. Young's modulus in the armchair direction is larger than in the zigzag order with all the different pore shapes. The yield strength in the armchair direction is smaller than that in the zigzag at all temperatures, all different pore shapes, and all defect rates except for the sample with a random porosity of 2%. The thermal conductivity depends on the sample direction, the defect morphologies due to the shrinkage of membranes are complicated, and all are smaller than the thermal conductivity of a perfect sample. The thermal conductivity of the perfect sample is highest at 300 K.

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“…Recently, the molecular dynamics (MD) simulation has been employed to investigate the machining and deformation mechanism of nano cutting process [33][34][35]. It provides a good insight into material behavior during the nanoscale cutting process, which is difficult to be observed experimentally.…”

Section: Introductionmentioning

confidence: 99%

Machining mechanism of polycrystalline nickel-based alloy under ultrasonic elliptical vibration-assisted cutting

Nguyen,

Fang,

Cai

et al. 2023

Modelling Simul. Mater. Sci. Eng.

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This work investigates the machining mechanism and deformation behavior of NiFeCo under conventional nanoscale cutting and ultrasonic elliptical vibration-assisted cutting (UEVC) through molecular dynamics simulation. The material removal process is considered in various vibration frequencies, amplitude ratios, and phase angles. In both cases, the highest shear strain, local stress, and temperature atoms are primarily located in the cutting area and chip volume, but the magnitudes are more significant under UEVC. The distribution analysis results of stacking fault and dislocation also show that grain boundaries strongly influence the deformation behavior and the local stress in the material. Moreover, in the cases of UEVC, the rise of vibration frequency and the decrease in amplitude ratio positively impact improving the material removal rate and reducing the average cutting force. Meanwhile, the change in phase angles affects only the timing of the peak in force value and has no significant effect on the resultant force and the cutting efficiency.

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Deformation and machining mechanism of nanocrystalline NiCoCrFe high entropy alloys

Cited by 18 publications

References 92 publications

Effects of grain boundary and gradient structure on machining property of CoCrFeMnNi alloys

Effects of grain boundary and gradient structure on machining property of CoCrFeMnNi alloys

Mechanical characteristics and thermal conductivity of defect single-layer buckled honeycomb germanene

Machining mechanism of polycrystalline nickel-based alloy under ultrasonic elliptical vibration-assisted cutting

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