Coupled Strengthening Effects by Lattice Distortion, Local Chemical Ordering, and Nanoprecipitates in Medium-Entropy Alloys

Extraordinary mechanical properties can be achieved in high-entropy alloys (HEAs) or medium-entropy alloys (MEAs) with nanoprecipitates. In the present study, the extra coupled strengthening effects by lattice distortion, local chemical ordering, and nanoprecipitates in the HEAs and MEAs with nanoprecipitates have been systematically investigated by large-scale molecular dynamics simulations. The moving of the dislocation can be slowed down, and the dislocation line shows a wavy configuration due to lattice distortion and local chemical ordering, resulting in strengthening. The degree of the wavy configuration increases and the sliding velocity of the dislocation decreases with increasing degrees of local chemical ordering. It is clearly indicated that the dislocation moves via nanoscale segment detrapping mechanism due to the effects of lattice distortion and local chemical ordering, resulting in roughened dislocation pathways for strengthening. The activated nanoscale segments are observed to be easier to detrap from the regions with stronger Co-Cr local chemical ordering and then propagate into the regions without such chemical ordering. These moving characteristics of the dislocation can delay the unpinning process from nanoprecipitates; thus, extra coupled strengthening effect has been revealed in the HEAs and MEAs with nanoprecipitates compared to pure Orowan’s strengthening.

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Effect of Interstitial Elements on the Cryogenic Mechanical Behavior of FCC High Entropy Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1016.1386 ◽

2021 ◽

Vol 1016 ◽

pp. 1386-1391

Author(s):

Anastasia Semenyuk ◽

Margarita Klimova ◽

Sergey Zherebtsov ◽

Nikita Stepanov

Keyword(s):

Mechanical Properties ◽

Solid Solution ◽

Thermomechanical Processing ◽

Induction Melting ◽

High Entropy Alloys ◽

Strengthening Effect ◽

Face Centered Cubic ◽

High Entropy ◽

C And N ◽

Interstitial Elements

High entropy alloys (HEAs) with face-centered cubic (fcc) structure, namely equiatomic CoCrFeMnNi alloy, have attracted considerable attention because of impressive cryogenic mechanical properties – strength, ductility, and fracture toughness. Further increase of the properties can be achieved, for example, by proper alloying. A particularly attractive option is the addition of interstitial elements like carbon or nitrogen. In present work, a series of CoCrFeMnNi-based alloys with different amounts of C and N (0-2 at.%) was prepared by induction melting. The alloys doped with C had lower Cr content to increase the solubility of carbon in the fcc solid solution. It was revealed that the solid solution strengthening effect of both C and N is significantly increased when the testing temperature decreases from 293K to 77K. The effect of thermomechanical processing on the structure and mechanical properties of the alloys is analyzed.

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Properties and Preparation of High Entropy Alloys

MATEC Web of Conferences ◽

10.1051/matecconf/201814203003 ◽

2018 ◽

Vol 142 ◽

pp. 03003 ◽

Cited By ~ 1

Author(s):

Xiang Yin ◽

Shuqiong Xu

Keyword(s):

Mechanical Properties ◽

Lattice Distortion ◽

Chemical Properties ◽

High Strength ◽

High Entropy Alloys ◽

Cocktail Party ◽

High Entropy ◽

Comprehensive Properties ◽

Cocktail Party Effect ◽

And Chemical Properties

As a consequence of multi-components, the high entropy alloys embodied serious cocktail party effect and lattice distortion. So high entropy alloys have high strength and hardness possess many comprehensive properties such as thermostability and corrosion resistance. Because of excellent mechanical properties and chemical properties, high entropy alloys have immeasurable potential of development. This paper mainly introduces the properties, preparations and applications of high entropy alloys, and finally summarizes them.

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Microstructural evolution and mechanical properties of AlxCoCrFeNi high-entropy alloys under uniaxial tension: A molecular dynamics simulations study

Materials Today Communications ◽

10.1016/j.mtcomm.2021.102525 ◽

2021 ◽

pp. 102525

Author(s):

Jun Jiang ◽

Pengwan Chen ◽

Jiali Qiu ◽

Weifu Sun ◽

Ivan Saikov ◽

...

Keyword(s):

Mechanical Properties ◽

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Uniaxial Tension ◽

Microstructural Evolution ◽

High Entropy Alloys ◽

High Entropy ◽

Dynamics Simulations

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Enhanced Mechanical Properties of Ti(C,B)-Based Cermets with Multi-Component AlCoCrFeNi High-Entropy Alloys Binder

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.727.149 ◽

2017 ◽

Vol 727 ◽

pp. 149-153 ◽

Cited By ~ 1

Author(s):

Gang Zhu ◽

Shao Xia Sun ◽

Jia Lin Chen ◽

Ming Xie ◽

Jie Qiong Hu

Keyword(s):

Mechanical Properties ◽

Precipitation Process ◽

High Entropy Alloys ◽

Strengthening Effect ◽

The Novel ◽

Modulated Structure ◽

High Entropy ◽

Novel Material ◽

Diffusion Solution ◽

Solution Mechanism

In this study, Ti (C,N)-based cermets with multi-component AlCoCrFeNi high-entropy alloys binder were successfully fabricated by mechanical alloying and low pressure sintering. The results indicate that the introduction of AlCoCrFeNi HEAs binder extended the formation process of (W,M)C rim phase by WC diffusion-solution mechanism, and repressed the precipitation process of the outer rim phase. On the other hand, the TEM micro-area analysis revealed a lath modulated structure, which massive nanoparticles are precipitated in the spinodal plate zone, 3-20nm in diameter. The nanocrystalline dispersion would provide an effective precipitation strengthening effect. The results of mechanical properties revealed that the cermets with AlCoCrFeNi HEAs binder achieved the co-enhancement of hardness and toughness. The novel material exhibits a high Vickers hardness of 1787 MPa, along with a good fracture toughness value of 11.4 MPa m1/2.

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Microstructure and Mechanical Properties of TaNbVTiAlx Refractory High-Entropy Alloys

Entropy ◽

10.3390/e22030282 ◽

2020 ◽

Vol 22 (3) ◽

pp. 282 ◽

Cited By ~ 1

Author(s):

Li Xiang ◽

Wenmin Guo ◽

Bin Liu ◽

Ao Fu ◽

Jianbo Li ◽

...

Keyword(s):

Mechanical Properties ◽

Solid Solution ◽

High Entropy Alloys ◽

Strengthening Effect ◽

High Entropy ◽

Solid Solution Strengthening ◽

Specific Strength ◽

Compression Properties ◽

Uniform Microstructure ◽

Solution Strengthening

A series of TaNbVTiAlx (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) refractory high-entropy alloys (RHEAs) with high specific strength and reasonable plasticity were prepared using powder metallurgy (P/M) technology. This paper studied their microstructure and compression properties. The results show that all the TaNbVTiAlx RHEAs exhibited a single BCC solid solution microstructure with no elemental segregation. The P/M TaNbVTiAlx RHEAs showed excellent room-temperature specific strength (207.11 MPa*cm3/g) and high-temperature specific strength (88.37 MPa*cm3/g at 900 °C and 16.03 MPa*cm3/g at 1200 °C), with reasonable plasticity, suggesting that these RHEAs have potential to be applied at temperatures >1200 °C. The reasons for the excellent mechanical properties of P/M TaNbVTiAl0.2 RHEA were the uniform microstructure and solid solution strengthening effect.

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

Applied Mathematics and Mechanics ◽

10.1007/s10483-021-2756-9 ◽

2021 ◽

Author(s):

Gangjie Luo ◽

Li Li ◽

Qihong Fang ◽

Jia Li ◽

Yuanyuan Tian ◽

...

Keyword(s):

Mechanical Properties ◽

Molecular Dynamics ◽

Dislocation Density ◽

Constitutive Model ◽

Lattice Distortion ◽

High Strength ◽

High Entropy Alloys ◽

Slip Systems ◽

Dislocation Loops ◽

High Entropy

AbstractHigh 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 $${a \over 6}\left[ {\bar 11\bar 2} \right]$$ a 6 [ 1 ¯ 1 2 ¯ ] and $${a \over 6}\left[ {1\bar 12} \right]$$ a 6 [ 1 1 ¯ 2 ] , 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.

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