Novel atomic-scale mechanism of incipient plasticity in a chemically complex CrCoNi medium-entropy alloy associated with inhomogeneity in local chemical environment

Cao, Fuhua; Wang, Yun-Jiang; Dai, Lan-Hong

doi:10.1016/j.actamat.2020.05.042

Cited by 111 publications

(19 citation statements)

References 85 publications

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“…More recently, it has been observed that the outstanding properties of these MPEs are neither confined to equiatomic composition nor the increasing number of alloying elements (increasing entropy), which was validated after a systematic study on the subsets of the quinary FeNiCoCrMn single-phase alloy [ 5 , 23 ]. Among all the studied compositions, the CoNiCr (MEA) exhibited a significantly higher yield and the highest tensile strength and oxidation and corrosion resistance as compared to other binary, ternary, or quaternary MPEs, including the FeNiCoCrMn system for a large spectrum of temperatures [ 13 , 18 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. Both from the experimental and theoretical point of view, the CoNiCr MEA is an extremely interesting model system, where the atomic radii mismatch is not so large as to produce an observed solid solution strengthening [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

Strange Metallicity and Magnetic Order in the CoNi(Cr/V) Medium-Entropy Alloy System

et al. 2023

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CoNiCr is a prototypical example of topical multi-principle element alloys with superior cryogenic and high-temperature mechanical strength, corrosion, oxidation resistance, and yet-to-be-explored magnetic and electronic functionalities. The remarkable properties of this transition metal ternary system are not only due to atomic radii, electronic configurational mismatch, and atomic volume misfit but are also dependent on the debated magnetically driven chemical short-range order. The current study focuses on the electric and magnetic properties of the single-phase face-centered cubic CoNi(Cr/V) system in which V is introduced to the system at the expense of Cr to fine-tune the volume misfit in the system. All the samples exhibited ultra-small magnetic moments due to the complex magnetic interactions of the constituent elements. The electric transport measurements revealed a strange metallicity evidenced through the observation of the linear temperature dependence of the resistivity. Our findings support the recent theoretical studies on the magnetically driven chemical short-range order of the CoNiCr system.

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Section: Introductionmentioning

confidence: 99%

Strange Metallicity and Magnetic Order in the CoNi(Cr/V) Medium-Entropy Alloy System

et al. 2023

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“…Of importance to plasticity studies, the potential is well characterized in terms of the energetics of the stacking faults (89). Since its introduction, the potential has been extensively used for studying the CrCoNi alloy (48,(90)(91)(92)(93), including the effects of lattice distortion and chemical short-range order on the deformation mechanisms of the CrCoNi alloy under shock loading (63,94).…”

Section: Simulationsmentioning

confidence: 99%

Deformation and failure of the CrCoNi medium-entropy alloy subjected to extreme shock loading

et al. 2023

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The extraordinary work hardening ability and fracture toughness of the face-centered cubic (fcc) high-entropy alloys render them ideal candidates for many structural applications. Here, the deformation and failure mechanisms of an equiatomic CrCoNi medium-entropyalloy (MEA) were investigated by powerful laser-driven shock experiments. Multiscale characterization demonstrates that profuse planar defects including stacking faults, nanotwins, and hexagonal nanolamella were generated during shock compression, forming a three-dimensional network. During shock release, the MEA fractured by strong tensile deformation and numerous voids was observed in the vicinity of the fracture plane. High defect populations, nanorecrystallization, and amorphization were found adjacent to these areas of localized deformation. Molecular dynamics simulations corroborate the experimental results and suggest that deformation-induced defects formed before void nucleation govern the geometry of void growth and delay their coalescence. Our results indicate that the CrCoNi-based alloys are impact resistant, damage tolerant, and potentially suitable in applications under extreme conditions.

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“…An experimental sample 34 of the polycrystalline (PC) NLDP HEA with coherent interphase boundaries (IPBs) is shown in Figure 1 a. Correspondingly, a representative PCNLDP HEA atomistic model with a random solid solution (RSS) structure 42 is constructed in Figure 1 b, where the atoms in the upper row of pictures with five different colors represent five elements, and the atoms in the lower row of pictures are colored with green for the FCC structure, red for the HCP structure, and white for the disordered structure. It should be noted that considering the limitation of computing ability of MD simulation, we therefore simplify the numerical model to nanoscale PC, which would not affect our main purpose of studying the effect of volume fraction of nanoscale phases on the deformation of the HEA.…”

Section: Atomistic Simulation Approachmentioning

confidence: 99%

Phase Volume Fraction-Dependent Strengthening in a Nano-Laminated Dual-Phase High-Entropy Alloy

2022

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A recently synthesized FCC/HCP nano-laminated dual-phase (NLDP) CoCrFeMnNi high entropy alloy (HEA) exhibits excellent strength–ductility synergy. However, the underlying strengthening mechanisms of such a novel material is far from being understood. In this work, large-scale atomistic simulations of in-plane tension of the NLDP HEA are carried out in order to explore the HCP phase volume fraction-dependent strengthening. It is found that the dual-phase (DP) structure can significantly enhance the strength of the material, and the strength shows apparent phase volume fraction dependence. The yield stress increases monotonously with the increase of phase volume fraction, resulting from the increased inhibition effect of interphase boundary (IPB) on the nucleation of partial dislocations in the FCC lamella. There exists a critical phase volume fraction, where the flow stress is the largest. The mechanisms for the volume fraction-dependent flow stress include volume fraction-dependent phase strengthening effect, volume fraction-dependent IPB strengthening effect, and volume fraction-dependent IPB softening effect, that is, IPB migration and dislocation nucleation from the dislocation–IPB reaction sites. This work can provide a fundamental understanding for the physical mechanisms of strengthening effects in face-centered cubic HEAs with a nanoscale NLDP structure.

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Novel atomic-scale mechanism of incipient plasticity in a chemically complex CrCoNi medium-entropy alloy associated with inhomogeneity in local chemical environment

Cited by 111 publications

References 85 publications

Strange Metallicity and Magnetic Order in the CoNi(Cr/V) Medium-Entropy Alloy System

Strange Metallicity and Magnetic Order in the CoNi(Cr/V) Medium-Entropy Alloy System

Deformation and failure of the CrCoNi medium-entropy alloy subjected to extreme shock loading

Phase Volume Fraction-Dependent Strengthening in a Nano-Laminated Dual-Phase High-Entropy Alloy

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