Hardening of an Al0.3CoCrFeNi high entropy alloy via high-pressure torsion and thermal annealing

Tang, Qingming; Huang, Yi; Huang, Youting; Liao, Xiaozhou; Langdon, Terence G.; Dai, Pinqiang

doi:10.1016/j.matlet.2015.03.066

Cited by 147 publications

(44 citation statements)

References 17 publications

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“…Formation of UFG microstructure after HPT at room temperature is well documented for various metallic materials [17] including high-entropy alloys [8][9][10][24][25][26]. The microstructure evolution during HPT is usually associated with the formation of low-angle grain boundaries at low strains and transformation of some of these low-angle subgrain boundaries into high-angle grain boundaries at higher strains giving rise to a considerable microstructure refinement.…”

Section: Discussionmentioning

confidence: 99%

Evolution of Microstructure and Mechanical Properties of a CoCrFeMnNi High-Entropy Alloy during High-Pressure Torsion at Room and Cryogenic Temperatures

Zherebtsov

Stepanov

Ivanisenko

et al. 2018

Metals

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High-pressure torsion (HPT) is applied to a face-centered cubic CoCrFeMnNi high-entropy alloy at 293 and 77 K. Processing by HPT at 293 K produced a nanostructure consisted of (sub)grains of~50 nm after a rotation for 180 • . The microstructure evolution is associated with intensive deformation-induced twinning, and substructure development resulted in a gradual microstructure refinement. Deformation at 77 K produces non-uniform structure composed of twinned and fragmented areas with higher dislocation density then after deformation at room temperature. The yield strength of the alloy increases with the angle of rotation at HPT at room temperature at the cost of reduced ductility. Cryogenic deformation results in higher strength in comparison with the room temperature HPT. The contribution of Hall-Petch hardening and substructure hardening in the strength of the alloy in different conditions is discussed.

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Section: Discussionmentioning

confidence: 99%

Evolution of Microstructure and Mechanical Properties of a CoCrFeMnNi High-Entropy Alloy during High-Pressure Torsion at Room and Cryogenic Temperatures

Zherebtsov

Stepanov

Ivanisenko

et al. 2018

Metals

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“…There are only a few reports describing the influence of HPT processing on HEAs [16][17][18][19][20] but it was shown for the CoCrFeNiMn alloy that processing by HPT leads to exceptional grain refinement to ~10 nm with a significant strength of ~1.75 GPa, a hardness of ~4. 41 GPa and with a very low ductility of ~4% at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Evidence for superplasticity in a CoCrFeNiMn high-entropy alloy processed by high-pressure torsion

Shahmir

Liu

et al. 2017

Materials Science and Engineering: A

106

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A CoCrFeNiMn high-entropy alloy was processed by high-pressure torsion to produce a grain size of ~10 nm and then tested in tension at elevated temperatures from 773 to 1073 K using strain rates in the range from 1.0 × 10 -3 to 1.0 × 10 -1 s -1 . The alloy exhibited excellent ductility at these elevated temperatures including superplastic elongations with a maximum elongation of >600% at a testing temperature of 973 K. It is concluded that the formation of precipitates and the sluggish diffusion in the HEA inhibit grain growth and contribute to a reasonable stability of the fine-grained structure at elevated temperatures. The results show the activation energy for flow matches the anticipated value for grain boundary diffusion in nickel but the strain rate sensitivity is low due to the occurrence of some grain growth at these high testing temperatures.

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“…However, the structure of HEA solid solutions are significantly different from those of Hume-Rothery terminal solid solutions, and this offers many potential applications, including tools, molds, and mechanical parts [11]. Despite those advances in studying microstructure and mechanical properties of mm-sized HEAs [12][13][14], systematic investigations into the mechanical behavior of annealed HEAs [15,16], especially at small scales, is lacking [17]. Praveeno et al [18] observed the phase transformation from BCC to sigma in CoFeNi-Cr HEAs after annealing at 500-600 • C. Wu [19] studied the phase stability and recovery, recrystallization, and grain growth of the FeNiCoCrMn HEAs after rolling and annealing.…”

Section: Introductionmentioning

confidence: 99%

Deformation Behavior of Al0.25CoCrFeNi High-Entropy Alloy after Recrystallization

Hou

Zhang

Yang

et al. 2017

Metals

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Cold rolling with subsequent annealing can be used to produce the recrystallized structure in high entropy alloys (HEAs). The Al 0.25 CoCrFeNi HEAs rolled to different final thickness (230, 400, 540, 800, 1000, 1500 µm) are prepared to investigate their microstructure evolutions and mechanical behaviors after annealing. Only the single face-centered cubic phase was obtained after cold rolling and recrystallization annealing at 1100 • C for 10 h. The average recrystallized grain size in this alloy after annealing ranges from 92 µm to 136 µm. The annealed thin sheets show obviously size effects on the flow stress and formability. The yield strength and tensile strength decrease as t/d (thickness/average grain diameter) ratio decreases until the t/d approaches 2.23. In addition, the stretchability (formability) decreases with the decrease of the t/d ratio especially when the t/d ratio is lower than about 6. According to the present results, yield strength can be expressed as a function of the t/d ratio.

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Hardening of an Al0.3CoCrFeNi high entropy alloy via high-pressure torsion and thermal annealing

Cited by 147 publications

References 17 publications

Evolution of Microstructure and Mechanical Properties of a CoCrFeMnNi High-Entropy Alloy during High-Pressure Torsion at Room and Cryogenic Temperatures

Evolution of Microstructure and Mechanical Properties of a CoCrFeMnNi High-Entropy Alloy during High-Pressure Torsion at Room and Cryogenic Temperatures

Evidence for superplasticity in a CoCrFeNiMn high-entropy alloy processed by high-pressure torsion

Deformation Behavior of Al0.25CoCrFeNi High-Entropy Alloy after Recrystallization

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