Effects of lattice distortion and chemical short-range order on the mechanisms of deformation in medium entropy alloy CoCrNi

Jian, Wu-Rong; Xie, Zhuocheng; Xu, Shuozhi; Su, Yanqing; Yao, Xiongliang; Beyerlein, Irene J.

doi:10.1016/j.actamat.2020.08.044

Cited by 255 publications

(65 citation statements)

References 91 publications

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“…Therefore, we turn to atomic-scale simulation tools to deepen our understanding of the SRO/mechanical behavior relationship in HEAs. The longer-time and larger-system size accessible with atomistic-simulation techniques, such as molecular dynamics (MD) 27 , 28 and Monte Carlo (MC) 29 – 31 , can provide insight into nanoscale phenomena in HEAs that are not easily accessible via first-principle calculations 32 , 33 . For example, Li et al 27 performed MD simulations of a nanocrystalline CoNiFeAl 0.3 Cu 0.7 HEA with grain sizes comparable to those in the experiments of Fu et al 34 and showed that the higher yield strength of the CoNiFeAl 0.3 Cu 0.7 HEA (1.8 GPa compared with most other FCC HEAs, 0.2–0.6 GPa) 35 – 37 was associated with a strain-induced FCC to BCC phase transition.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Hybrid MC/MD simulations have proven to be a powerful tool to explore the effects of atomic segregation and SRO on the mechanical properties of MEAs and HEAs 29 – 31 . For example, Jian et al 29 used hybrid MC and MD simulations to investigate the role of lattice distortion (LD) and SRO on the formation and evolution of dislocations in a CoCrNi MEA. These simulations suggested that yield strength was controlled by the strain required to nucleate Shockley partial dislocations; LD lowered this strain, while SRO increased it.…”

Section: Introductionmentioning

confidence: 99%

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Simultaneously enhancing the ultimate strength and ductility of high-entropy alloys via short-range ordering

et al. 2021

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Simultaneously enhancing strength and ductility of metals and alloys has been a tremendous challenge. Here, we investigate a CoCuFeNiPd high-entropy alloy (HEA), using a combination of Monte Carlo method, molecular dynamic simulation, and density-functional theory calculation. Our results show that this HEA is energetically favorable to undergo short-range ordering (SRO), and the SRO leads to a pseudo-composite microstructure, which surprisingly enhances both the ultimate strength and ductility. The SRO-induced composite microstructure consists of three categories of clusters: face-center-cubic-preferred (FCCP) clusters, indifferent clusters, and body-center-cubic-preferred (BCCP) clusters, with the indifferent clusters playing the role of the matrix, the FCCP clusters serving as hard fillers to enhance the strength, while the BCCP clusters acting as soft fillers to increase the ductility. Our work highlights the importance of SRO in influencing the mechanical properties of HEAs and presents a fascinating route for designing HEAs to achieve superior mechanical properties.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simultaneously enhancing the ultimate strength and ductility of high-entropy alloys via short-range ordering

et al. 2021

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“…Specifically, to investigate the deformation of RHEAs, transmission electron microscopy (TEM) studies on RHEAs have shown a dominant role of screw dislocations with increasing plastic strain 18 , 19 , and slip activity on high-order-planes has been observed through in situ scanning electron microscopy experiments 16 ; indeed, strong intrinsic lattice resistance has been generally found in these concentrated solid-solution alloys 19 , 20 . Theoretical models for strengthening in RHEAs by screw dislocations have been developed 21 , 22 , and atomistic simulations of dislocation properties using molecular dynamics (MD) and density-functional theory (DFT) calculations have been undertaken 23 – 27 . Recently, mesoscale models, such as a kinetic Monte Carlo model, have also been developed to investigate the strengthening in RHEAs 28 .…”

Section: Introductionmentioning

confidence: 99%

Atomistic simulations of dislocation mobility in refractory high-entropy alloys and the effect of chemical short-range order

et al. 2021

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Refractory high-entropy alloys (RHEAs) are designed for high elevated-temperature strength, with both edge and screw dislocations playing an important role for plastic deformation. However, they can also display a significant energetic driving force for chemical short-range ordering (SRO). Here, we investigate mechanisms underlying the mobilities of screw and edge dislocations in the body-centered cubic MoNbTaW RHEA over a wide temperature range using extensive molecular dynamics simulations based on a highly-accurate machine-learning interatomic potential. Further, we specifically evaluate how these mechanisms are affected by the presence of SRO. The mobility of edge dislocations is found to be enhanced by the presence of SRO, whereas the rate of double-kink nucleation in the motion of screw dislocations is reduced, although this influence of SRO appears to be attenuated at increasing temperature. Independent of the presence of SRO, a cross-slip locking mechanism is observed for the motion of screws, which provides for extra strengthening for refractory high-entropy alloy system.

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“…Although some site preferences may present in the studied systems, [ 8,26 ] the local ordering behavior, short‐order behavior, and the site preference on sublattice are complicated and beyond the present study. In this work, only the random distribution is chosen as an ideal case, which may be not the real case.…”

Section: Methodsmentioning

confidence: 99%

Influence of Local Lattice Distortion on Elastic Properties of Hexagonal Close‐Packed TiZrHf and TiZrHfSc Refractory Alloys

Meng

Duan

Chen

et al. 2021

Physica Status Solidi (b)

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The unique mechanical properties and local lattice distortion (LLD) for hexagonal close‐packed (HCP) multiple principal element alloys (MPEAs) are very rarely studied so far. Employing density functional theory calculation based on special quasirandom structure, this work studies the influences of LLD on elastic properties for both novel hexagonal TiZrHf(Sc) MPEAs. Compared to the pristine structures, the lattice stability of distorted random structures is improved evidently. Moreover, LLD obviously lessens the shear elastic properties, which may be an ubiquitous phenomenon irrespective of the lattice types of MPEAs. These results also uncover the apparent improvement in malleable behavior and shear anisotropy for HCP MPEAs. So, the influence of LLD on elastic properties for HCP MPEAs is profound. The degree of LLD is further studied via the standard deviation of near‐neighbor (NN) and next NN bond length distributions as an effective indicator of LLD. More significant distortion uncovered in TiZrHf alloy corresponds consistently to the stronger effects of LLD in TiZrHf alloy. Bader's charge and charge density distribution also demonstrate the underlying impact on LLD for both HCP MPEAs, so electronic nature is a significant factor for LLD. The present study provides guideline for designing mechanical properties of TiZrHf‐based HCP MPEAs engineering materials.

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Effects of lattice distortion and chemical short-range order on the mechanisms of deformation in medium entropy alloy CoCrNi

Cited by 255 publications

References 91 publications

Simultaneously enhancing the ultimate strength and ductility of high-entropy alloys via short-range ordering

Simultaneously enhancing the ultimate strength and ductility of high-entropy alloys via short-range ordering

Atomistic simulations of dislocation mobility in refractory high-entropy alloys and the effect of chemical short-range order

Influence of Local Lattice Distortion on Elastic Properties of Hexagonal Close‐Packed TiZrHf and TiZrHfSc Refractory Alloys

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