Simultaneous twinning and microband formation under dynamic compression in a high entropy alloy with a complex energetic landscape

Foley, Daniel J.; Huang, Sirui; Anber, Elaf A.; Shanahan, L.; Shen, Yixi; Lang, Andrew C.; Barr, Christopher M.; Spearot, Douglas E.; Lamberson, Leslie; Taheri, Mitra L.

doi:10.1016/j.actamat.2020.08.047

Cited by 69 publications

(19 citation statements)

References 50 publications

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Section: Microstructure Characterizationsupporting

confidence: 91%

“…These studies indicate that microbanding occurred as a result of either a decreased SFE or an increase in the Peierls barrier, both consequences of decreased temperature. This clearly explains the current observations of the formation of microbands [32]. Moreover, microbands were found in the sample fractured at 77 K; as shown in Figure 6, the SEAD along <110> zone axis revealed no twinning spots, ruling out the possibility that these structures are twins.…”

Section: Microstructure Characterizationsupporting

confidence: 84%

“…It seems reasonable to expect microbands to appear in the current MEA, which had added aluminum and silicon. Furthermore, Wang et al [31] reported the formation of microbands but not twins in carbon-doped Fe 40.4 Ni 11.3 Mn 34.8 Al 7.5 Cr 6 HEA when compressed at temperatures ranging from 77 to 673 K. Foley et al [32] investigated CoCrFeMnNi under quasistatic and dynamic compression, finding that deformation at 8 × 10 3 s −1 led to the formation of both twins and microbands. These studies indicate that microbanding occurred as a result of either a decreased SFE or an increase in the Peierls barrier, both consequences of decreased temperature.…”

Section: Microstructure Characterizationmentioning

confidence: 99%

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Enhanced Strength and Plasticity of CoCrNiAl0.1Si0.1 Medium Entropy Alloy via Deformation Twinning and Microband at Cryogenic Temperature

Liu¹,

Meng

Chang

et al. 2021

Materials

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The synthesis of lightweight yet strong-ductile materials has been an imperative challenge in alloy design. In this study, the CoCrNi-based medium-entropy alloys (MEAs) with added Al and Si were manufactured by vacuum arc melting furnace subsequently followed by cool rolling and anneal process. The mechanical responses of CoCrNiAl0.1Si0.1 MEAs under quasi-static (1 × 10−3 s−1) tensile strength showed that MEAs had an outstanding balance of yield strength, ultimate tensile strength, and elongation. The yield strength, ultimate tensile strength, and elongation were increased from 480 MPa, 900 MPa, and 58% at 298 K to 700 MPa, 1250 MPa, and 72% at 77 K, respectively. Temperature dependencies of the yield strength and strain hardening were investigated to understand the excellent mechanical performance, considering the contribution of lattice distortions, deformation twins, and microbands. Severe lattice distortions were determined to play a predominant role in the temperature-dependent yield stress. The Peierls barrier height increased with decreasing temperature, owing to thermal vibrations causing the effective width of a dislocation core to decrease. Through the thermodynamic formula, the stacking fault energies were calculated to be 14.12 mJ/m2 and 8.32 mJ/m2 at 298 K and 77 K, respectively. In conclusion, the enhanced strength and ductility at cryogenic temperature can be attributed to multiple deformation mechanisms including dislocations, extensive deformation twins, and microbands. The synergistic effect of multiple deformation mechanisms lead to the outstanding mechanical properties of the alloy at room and cryogenic temperature.

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Section: Microstructure Characterizationsupporting

confidence: 91%

Section: Microstructure Characterizationsupporting

confidence: 84%

Section: Microstructure Characterizationmentioning

confidence: 99%

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Enhanced Strength and Plasticity of CoCrNiAl0.1Si0.1 Medium Entropy Alloy via Deformation Twinning and Microband at Cryogenic Temperature

Liu¹,

Meng

Chang

et al. 2021

Materials

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“…Previously, the resistance to shear localization for single phase Al 0.3 CoCrFeNi alloy, at high strain rates was attributed to the excellent strain hardenability from forest dislocation hardening, mechanical twinning, and solid solution strengthening 14 . Also, in low-SFE HEAs, the distribution of SFE is inhomogeneous since chemical ordering of constituent elements varies throughout the lattice 34 . Due to this complex energy landscape, the deformation mechanism may vary and lead to simultaneous twinning and microband formation during deformation 34 .…”

Section: Resultsmentioning

confidence: 99%

“…Also, in low-SFE HEAs, the distribution of SFE is inhomogeneous since chemical ordering of constituent elements varies throughout the lattice 34 . Due to this complex energy landscape, the deformation mechanism may vary and lead to simultaneous twinning and microband formation during deformation 34 . Note that in our current examination, we did not notice any signature of micro- or nano-scale twinning that has been previously reported.…”

Section: Resultsmentioning

confidence: 99%

Excellent ballistic impact resistance of Al0.3CoCrFeNi multi-principal element alloy with unique bimodal microstructure

Muskeri

Gwalani

Jha

et al. 2021

Sci Rep

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Multi-principal element alloys represent a new paradigm in structural alloy design with superior mechanical properties and promising ballistic performance. Here, the mechanical response of Al0.3CoCrFeNi alloy, with unique bimodal microstructure, was evaluated at quasistatic, dynamic, and ballistic strain rates. The microstructure after quasistatic deformation was dominated by highly deformed grains. High density of deformation bands was observed at dynamic strain rates but there was no indication of adiabatic shear bands, cracks, or twinning. The ballistic response was evaluated by impacting a 12 mm thick plate with 6.35 mm WC projectiles at velocities ranging from 1066 to 1465 m/s. The deformed microstructure after ballistic impact was dominated by adiabatic shear bands, shear band induced cracks, microbands, and dynamic recrystallization. The superior ballistic response of this alloy compared with similar AlxCoCrFeNi alloys was attributed to its bimodal microstructure, nano-scale L12 precipitation, and grain boundary B2 precipitates. Deformation mechanisms at quasistatic and dynamic strain rates were primarily characterized by extensive dislocation slip and low density of stacking faults. Deformation mechanisms at ballistic strain rates were characterized by grain rotation, disordering of the L12 phase, and high density of stacking faults.

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Dynamic Mechanical Behavior and Microstructure of the Al_0.1CoCrFeNiTi_x High‐Entropy Alloys

Tian

Wang

et al. 2021

Adv Eng Mater

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The effects of the microstructure and the strain rate on the compression behavior of the Al0.1CoCrFeNiTi x (x = 0.1, 0.3, and 0.5 in molar ratio) high‐entropy alloys (HEAs) are investigated. Compared with the Al0.1CoCrFeNiTi0.1 with the single‐phase face‐centered cubic (FCC) structure and the Al0.1CoCrFeNiTi0.3 HEAs, both the yield strength (YS) and the work hardening ability of the Al0.1CoCrFeNiTi0.5 HEA are enhanced significantly under the quasistatic condition. This is due to a combination of the solid‐solution strengthening and sigma‐phase precipitation hardening mechanisms. The strong work hardening of the Al0.1CoCrFeNiTi0.1 HEAs under quasistatic loading is attributed to the existence of the dislocation substructures (high‐density dislocation walls and dislocation cells) and the deformation twinning accompanying homogeneous deformation. A significant strain rate sensitivity on the YS is obtained as a result of the phonon drag effect under dynamic loading. Different from the quasistatic condition, the dynamic grain refinement and the nanoscale twins inside the grains are the main microstructure characteristics in the dynamic deformation process.

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Simultaneous twinning and microband formation under dynamic compression in a high entropy alloy with a complex energetic landscape

Cited by 69 publications

References 50 publications

Enhanced Strength and Plasticity of CoCrNiAl0.1Si0.1 Medium Entropy Alloy via Deformation Twinning and Microband at Cryogenic Temperature

Enhanced Strength and Plasticity of CoCrNiAl0.1Si0.1 Medium Entropy Alloy via Deformation Twinning and Microband at Cryogenic Temperature

Excellent ballistic impact resistance of Al0.3CoCrFeNi multi-principal element alloy with unique bimodal microstructure

Dynamic Mechanical Behavior and Microstructure of the Al_0.1CoCrFeNiTi_x High‐Entropy Alloys

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Simultaneous twinning and microband formation under dynamic compression in a high entropy alloy with a complex energetic landscape

Cited by 69 publications

References 50 publications

Enhanced Strength and Plasticity of CoCrNiAl0.1Si0.1 Medium Entropy Alloy via Deformation Twinning and Microband at Cryogenic Temperature

Enhanced Strength and Plasticity of CoCrNiAl0.1Si0.1 Medium Entropy Alloy via Deformation Twinning and Microband at Cryogenic Temperature

Excellent ballistic impact resistance of Al0.3CoCrFeNi multi-principal element alloy with unique bimodal microstructure

Dynamic Mechanical Behavior and Microstructure of the Al0.1CoCrFeNiTix High‐Entropy Alloys

Contact Info

Product

Resources

About

Dynamic Mechanical Behavior and Microstructure of the Al_0.1CoCrFeNiTi_x High‐Entropy Alloys