Molecular dynamics simulations of tensile response for FeNiCrCoCu high-entropy alloy with voids

Vacancy dependent mechanical behaviors of high-entropy alloy

Dislocation reaction-based formation mechanism of stacking fault tetrahedra in FCC high-entropy alloy

Shock-induced dynamic response in single and nanocrystalline high-entropy alloy FeNiCrCoCu

Multicomponent alloys possessing nanocrystalline structure, often alluded to as Cantor alloys or high entropy alloys (HEAs), continue to attract the great attention of the research community. It has been suggested that about 64 elements in the periodic table can be mixed in various compositions to synthesize as many as ∼108 different types of HEA alloys. Nanomechanics of HEAs combining experimental and atomic simulations are rather scarce in the literature, which was a major motivation behind this work. In this spirit, a novel high-entropy alloy (Ni25Cu18.75Fe25Co25Al6.25) was synthesized using the arc melting method, which followed a joint simulation and experimental effort to investigate dislocation-mediated plastic mechanisms leading to side flow, pileup, and crystal defects formed in the sub-surface of the HEA during and after the scratch process. The major types of crystal defects associated with the plastic deformation of the crystalline face-centered cubic structure of HEA were 2,3,4-hcp layered such as defect coordination structures, coherent ∑3 twin boundary, and ∑11 fault or tilt boundary, in combination with Stair rods, Hirth locks, Frank partials, and Lomer–Cottrell locks. Moreover, 1/6 <112> Shockley, with exceptionally larger dislocation loops, was seen to be the transporter of stacking faults deeper into the substrate than the location of the applied cutting load. The (100) orientation showed the highest value for the kinetic coefficient of friction but the least amount of cutting stress and cutting temperature during HEA deformation, suggesting that this orientation is better than the other orientations for improved contact-mode manufacturing.

https://aip.scitation.org/doi/pdf/10.1063/5.0128135

Uniaxial pulling and nano-scratching of a newly synthesized high entropy alloy

High entropy alloys (HEAs) attract remarkable attention due to the excellent mechanical performance. However, the origins of their high strength and toughness compared with those of the traditional alloys are still hardly revealed. Here, using a microstructure-based constitutive model and molecular dynamics (MD) simulation, we investigate the unique mechanical behavior and microstructure evolution of FeCoCrNiCu HEAs during the indentation. Due to the interaction between the dislocation and solution, the high dislocation density in FeCoCrNiCu leads to strong work hardening. Plentiful slip systems are stimulated, leading to the good plasticity of FeCoCrNiCu. The plastic deformation of FeCoCrNiCu is basically affected by the motion of dislocation loops. The prismatic dislocation loops inside FeCoCrNiCu are formed by the dislocations with the Burgers vectors of $${a \over 6}\left[ {\bar 11\bar 2} \right]$$
 and $${a \over 6}\left[ {1\bar 12} \right]$$
 , which interact with each other, and then emit along the 〈111〉 slip direction. In addition, the mechanical properties of FeCoCrNiCu HEA can be predicted by constructing the microstructure-based constitutive model, which is identified according to the evolution of the dislocation density and the stress-strain curve. Strong dislocation strengthening and remarkable lattice distortion strengthening occur in the deformation process of FeCoCrNiCu, and improve the strength. Therefore, the origins of high strength and high toughness in FeCoCrNiCu HEAs come from lattice distortion strengthening and the more activable slip systems compared with Cu. These results accelerate the discovery of HEAs with excellent mechanical properties, and provide a valuable reference for the industrial application of HEAs.

/pdf/microstructural-evolution-and-mechanical-properties-of-1io7uhrr8p.pdf

Microstructural evolution and mechanical properties of FeCoCrNiCu high entropy alloys: a microstructure-based constitutive model and a molecular dynamics simulation study

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Li Liang

Papers

Microstructural evolution and mechanical properties of FeCoCrNiCu high entropy alloys: a microstructure-based constitutive model and a molecular dynamics simulation study

Broken bone temporary fixing device in orthopedics art