Stacking fault energies of face-centered cubic concentrated solid solution alloys

High-entropy alloys (HEAs) are an intriguing new class of metallic materials due to their unique mechanical behavior. Achieving a detailed understanding of structure-property relationships in these materials has been challenged by the compositional disorder that underlies their unique mechanical behavior. Accordingly, in this work, we employ first-principles calculations to investigate the nature of local chemical order and establish its relationship to the intrinsic and extrinsic stacking fault energy (SFE) in CrCoNi medium-entropy solid-solution alloys, whose combination of strength, ductility, and toughness properties approaches the best on record. We find that the average intrinsic and extrinsic SFE are both highly tunable, with values ranging from -43 to 30 mJ⋅m and from -28 to 66 mJ⋅m, respectively, as the degree of local chemical order increases. The state of local ordering also strongly correlates with the energy difference between the face-centered cubic () and hexagonal close-packed () phases, which affects the occurrence of transformation-induced plasticity. This theoretical study demonstrates that chemical short-range order is thermodynamically favored in HEAs and can be tuned to affect the mechanical behavior of these alloys. It thus addresses the pressing need to establish robust processing-structure-property relationships to guide the science-based design of new HEAs with targeted mechanical behavior.

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“…3E, for a large number of samples to achieve wellconverged averaged results (only limited configurations were considered in refs. [11,17,25]…”

Section: Local Chemical Order In Crconi Solid-solution Alloysmentioning

confidence: 99%

Tunable stacking fault energies by tailoring local chemical order in CrCoNi medium-entropy alloys

Ding

Asta

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

629

243

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“…The advantage of this method is that it is possible to calculate several alloy compositions with less effort than the one required for an experimental determination of the same alloys. So far, the systems CoCrFeMnNi [9,10,13,14], AlCoCrCuFeNi, and AlCoCrFeNi [15] have been investigated regarding their SFE. A comprehensive list can be found in Reference [12].…”

mentioning

confidence: 99%

From High-Manganese Steels to Advanced High-Entropy Alloys

Haase

Barrales‐Mora

2019

Metals

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Arguably, steels are the most important structural material, even to this day. Numerous design concepts have been developed to create and/or tailor new steels suited to the most varied applications. High-manganese steels (HMnS) stand out for their excellent mechanical properties and their capacity to make use of a variety of physical mechanisms to tailor their microstructure, and thus their properties. With this in mind, in this contribution, we explore the possibility of extending the alloy design concepts that haven been used successfully in HMnS to the recently introduced high-entropy alloys (HEA). To this aim, one HMnS steel and the classical HEA Cantor alloy were subjected to cold rolling and heat treatment. The evolution of the microstructure and texture during the processing of the alloys and the resulting properties were characterized and studied. Based on these results, the physical mechanisms active in the investigated HMnS and HEA were identified and discussed. The results evidenced a substantial transferability of the design concepts and more importantly, they hint at a larger potential for microstructure and property tailoring in the HEA. several core effects (high-entropy effect, sever lattice distortion effect, sluggish diffusion effect, cocktail effect) of HEAs have been proposed [5], a clear design strategy is still missing.The underlying physical mechanisms active in HMnS have already been studied for several decades [1,2,6], and therefore are comparatively well understood. One of the most important parameters when designing HMnS is the tailoring of their stacking fault energy (SFE). This property controls the dissociation distance of partial dislocations and determines whether TRIP and/or TWIP is activated/suppressed during plastic deformation. The role of the SFE during plastic deformation and subsequent heat treatment in metals has been studied for decades, and its effect is relatively well-known for face-centered cubic (fcc) metals [7]. In fcc HEAs, the mechanisms of microstructure formation have been found to occur in a similar way to the same class of alloys with comparable SFE [8]. For instance, the Cantor alloy (CoCrFeMnNi) with an estimated SFE between 18.3-27.3 mJ/m 2 [9,10] has been shown to develop the TWIP effect, depending on the processing conditions [11]. Evidently, the determination of the SFE in HEAs is fundamental, because this property indicates the possible acting mechanisms for microstructure development. However, as with steels, the complex chemistry of HEAs leads to almost unlimited combinations that make a systematic determination of this property difficult. Nevertheless, to accelerate the development of these alloys, several research groups have made use of ab initio calculations, e.g., [12]. The advantage of this method is that it is possible to calculate several alloy compositions with less effort than the one required for an experimental determination of the same alloys. So far, the systems CoCrFeMnNi [9,10,13,14], AlCoCrCuFeNi, and AlCoCrFeNi [15] have been investig...

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“…What is more, modulating the chemical compositions and concentrations can optimize the stacking fault energy (SFE), enabling to induce twinning‐induced plasticity and transformation‐induced plasticity (TRIP) effects 31,106,107. Ab initio calculations show that the SFE is the energy that interrupts the normal stacking sequence of a crystal plane and positively correlates with temperature 108,109. The SFE may diminish with the decreasing of the temperature, enabling the sliding needed for a displacive phase transition from FCC to HCP phase 52.…”

Section: Phase Engineering Of Heasmentioning

confidence: 99%

“…[31,106,107] Ab initio calculations show that the SFE is the energy that interrupts the normal stacking sequence of a crystal plane and positively correlates with temperature. [108,109] The SFE may diminish with the decreasing of the temperature, enabling the sliding needed for a displacive phase transition from FCC to HCP phase. [52] Liao et al reported the polymorphic phase transformation in FeCoCrNi HEA induced by the cryogenic deformation.…”

Section: Temperature Controllingmentioning

confidence: 99%

Phase Engineering of High‐Entropy Alloys

et al. 2020

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High‐entropy alloys (HEAs) are based on five or more principal elements with equal or nearly equal molar fractions and possess many significant advantages over traditional alloys, including high strength and hardness, excellent corrosion resistance, outstanding thermal stability, and irradiation resistance. Phase structure plays a vital role in determining the property of HEAs. For further enhancing the performance of HEAs in various application fields, a controllable synthesis with desired phases is required. In this review, the diverse phase structures of HEAs and the related properties are first introduced. Then, alternative tuning strategies to promote the desired phase structure of HEAs are focused upon. Property adjusting of phase‐engineered HEAs is also discussed in depth. Lastly, some insights into the challenges and future prospects in this rapidly emerging research field are provided.

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Stacking fault energies of face-centered cubic concentrated solid solution alloys

Cited by 388 publications

References 53 publications

Tunable stacking fault energies by tailoring local chemical order in CrCoNi medium-entropy alloys

Tunable stacking fault energies by tailoring local chemical order in CrCoNi medium-entropy alloys

From High-Manganese Steels to Advanced High-Entropy Alloys

Phase Engineering of High‐Entropy Alloys

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