Real-time observations of TRIP-induced ultrahigh strain hardening in a dual-phase CrMnFeCoNi high-entropy alloy

Chen, Sijing; Oh, Hyun Seok; Gludovatz, Bernd; Kim, Sang Jun; Park, Eun Soo; Zhang, Ze; Ritchie, Robert O.; Yu, Qian

doi:10.1038/s41467-020-14641-1

Cited by 207 publications

(66 citation statements)

References 35 publications

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“…As the deformation proceeds, the density of SF networks and LC locks increases. The LC locks derive their effectiveness in strain hardening from their capability to accumulate dislocations from the two aspects: on the one hand, LC locks serve to stabilize the SF network by pinning lockforming dislocation segments, because when two dislocations meet to produce an LC lock, four dislocation segments are pinned 28 , and on the other hand, the sessile nature of the stair-rod dislocation in the LC locks enables them to exhibit high structural stability resistant to dissociations and to block other dislocation motion as a barrier, which consequently presents a strong hindering effect on dislocation motion 29 . In addition, the hierarchical SF networks dynamically subdivide the ultrafine grains into even finer sub-grains during deformation (with sizes of~20 nm at the 16% strain) (Fig.…”

Section: Discussionmentioning

confidence: 99%

Ultrahigh strength and ductility in newly developed materials with coherent nanolamellar architectures

et al. 2020

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Nano-lamellar materials with ultrahigh strengths and unusual physical properties are of technological importance for structural applications. However, these materials generally suffer from low tensile ductility, which severely limits their practical utility. Here we show that markedly enhanced tensile ductility can be achieved in coherent nano-lamellar alloys, which exhibit an unprecedented combination of over 2 GPa yield strength and 16% uniform tensile ductility. The ultrahigh strength originates mainly from the lamellar boundary strengthening, whereas the large ductility correlates to a progressive work-hardening mechanism regulated by the unique nano-lamellar architecture. The coherent lamellar boundaries facilitate the dislocation transmission, which eliminates the stress concentrations at the boundaries. Meanwhile, deformation-induced hierarchical stacking-fault networks and associated high-density Lomer-Cottrell locks enhance the work hardening response, leading to unusually large tensile ductilities. The coherent nano-lamellar strategy can potentially be applied to many other alloys and open new avenues for designing ultrastrong yet ductile materials for technological applications.

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Section: Discussionmentioning

confidence: 99%

Ultrahigh strength and ductility in newly developed materials with coherent nanolamellar architectures

et al. 2020

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“…Moreover, the material consists of a certain volume fraction of HCP phase after HPT at LNT. In an HEA of different composition (Cr 20 Mn 6 Fe 34 Co 34 Ni 6 ), which is prone to the same phase transformation, compression of micro pillars shows that the HCP phase is harder than the FCC one [43]. This also explains the higher strength measured for the dual phase alloy Cr 10 Mn 30 Fe 50 Co 10 [44].…”

Section: Strength Developmentmentioning

confidence: 97%

Microstructure, Texture, and Strength Development during High-Pressure Torsion of CrMnFeCoNi High-Entropy Alloy

et al. 2020

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The equiatomic face-centered cubic high-entropy alloy CrMnFeCoNi was severely deformed at room and liquid nitrogen temperature by high-pressure torsion up to shear strains of about 170. Its microstructure was analyzed by X-ray line profile analysis and transmission electron microscopy and its texture by X-ray microdiffraction. Microhardness measurements, after severe plastic deformation, were done at room temperature. It is shown that at a shear strain of about 20, a steady state grain size of 24 nm, and a dislocation density of the order of 1016 m−2 is reached. The dislocations are mainly screw-type with low dipole character. Mechanical twinning at room temperature is replaced by a martensitic phase transformation at 77 K. The texture developed at room temperature is typical for sheared face-centered cubic nanocrystalline metals, but it is extremely weak and becomes almost random after high-pressure torsion at 77 K. The strength of the nanocrystalline material produced by high-pressure torsion at 77 K is lower than that produced at room temperature. The results are discussed in terms of different mechanisms of deformation, including dislocation generation and propagation, twinning, grain boundary sliding, and phase transformation.

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“…Precipitated phases can be used to increase strength [ 9 ] and wear resistance, as in conventional non-high-entropy alloys [ 10 ]. One famous high entropy alloy is the so called Cantor alloy [ 11 ] which is investigated in various studies for example references [ 12 , 13 ] including its derivatives. This high entropy alloy and its derivatives consist of near equiatomic CrCoFeMnNi.…”

Section: Introductionmentioning

confidence: 99%

Re-Melting Behaviour and Wear Resistance of Vanadium Carbide Precipitating Cr27.5Co14Fe22Mo22Ni11.65V2.85 High Entropy Alloy

2021

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High entropy alloys (HEAs) are among of the most promising new metal material groups. The achievable properties can exceed those of common alloys in different ways. Due to the mixture of five or more alloying elements, the variety of high entropy alloys is fairly huge. The presented work will focus on some first insights on the weldability and the wear behavior of vanadium carbide precipitation Cr27.5Co14Fe22Mo22Ni11.65V2.85 HEA. The weldability should always be addressed in an early stage of any alloy design to avoid welding-related problems afterwards. The cast Cr27.5Co14Fe22Mo22Ni11.65V2.85 HEA has been remelted using a TIG welding process and the resulting microstructure has been examined. The changes in the microstructure due to the remelting process showed little influence of the welding process and no welding-related problems like hot cracks have been observed. It will be shown that vanadium carbides or vanadium-rich phases precipitate after casting and remelting in a two phased HEA matrix. The hardness of the as cast alloy is 324HV0.2 and after remelting the hardness rises to 339HV0.2. The wear behavior can be considered as comparable to a Stellite 6 cobalt base alloy as determined in an ASTM G75 test. Overall, the basic HEA design is promising due to the precipitation of vanadium carbides and should be further investigated.

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Real-time observations of TRIP-induced ultrahigh strain hardening in a dual-phase CrMnFeCoNi high-entropy alloy

Cited by 207 publications

References 35 publications

Ultrahigh strength and ductility in newly developed materials with coherent nanolamellar architectures

Ultrahigh strength and ductility in newly developed materials with coherent nanolamellar architectures

Microstructure, Texture, and Strength Development during High-Pressure Torsion of CrMnFeCoNi High-Entropy Alloy

Re-Melting Behaviour and Wear Resistance of Vanadium Carbide Precipitating Cr27.5Co14Fe22Mo22Ni11.65V2.85 High Entropy Alloy

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