Gradient recrystallization to improve strength and ductility of medium-entropy alloy

Liu, Yao; He, Yue; Cai, Songlin

doi:10.1016/j.jallcom.2020.157388

Cited by 15 publications

(3 citation statements)

References 56 publications

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“…The size of these small grains is less than 1 µm; thus, they can be considered ultrafine grains (UFGs). It is generally thought that the surface layer with more stored deformation energy during the SMAT is easier to form RXGs during the subsequent short-time annealing [46,47], which is consistent with the observations in Figure 1.…”

Section: Resultssupporting

confidence: 86%

Simultaneous Improvement of Yield Strength and Ductility at Cryogenic Temperature by Gradient Structure in 304 Stainless Steel

et al. 2021

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The tensile properties and the corresponding deformation mechanism of the graded 304 stainless steel (ss) at both room and cryogenic temperatures were investigated and compared with those of the coarse-grained (CGed) 304 ss. Gradient structures were found to have excellent synergy of strength and ductility at room temperature, and both the yield strength and the uniform elongation were found to be simultaneously improved at cryogenic temperature in the gradient structures, as compared to those for the CG sample. The hetero-deformation-induced (HDI) hardening was found to play a more important role in the gradient structures as compared to the CG sample and be more obvious at cryogenic temperature as compared to that at room temperature. The central layer in the gradient structures provides stronger strain hardening during tensile deformation at both temperatures, due to more volume fraction of martensitic transformation. The volume fraction of martensitic transformation in the gradient structures was found to be much higher at cryogenic temperature, resulting in a much stronger strain hardening at cryogenic temperature. The amount of martensitic transformation at the central layer of the gradient structures is observed to be even higher than that for the CG sample at cryogenic temperature, which is one of the origins for the simultaneous improvement of strength and ductility by the gradient structures at cryogenic temperature.

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Section: Resultssupporting

confidence: 86%

Simultaneous Improvement of Yield Strength and Ductility at Cryogenic Temperature by Gradient Structure in 304 Stainless Steel

et al. 2021

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“…However, it could be obvious in the heterogeneous grain structure in single-phase alloys with low SFE. Heterogeneous structures are usually obtained by annealing the heavily deformed alloys at low temperatures for a short time [105][106][107][108] .…”

Section: Heterogeneous Structurementioning

confidence: 99%

A critical review of the mechanical properties of CoCrNi-based medium-entropy alloys

Xu¹,

Wang²,

Li³

et al. 2022

Microstructures

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The CoCrFeMnNi alloy is one of the most notable first-generation high-entropy alloys and is also known as a Cantor alloy. This alloy was first proposed in 2004 and shows promising performance at cryogenic temperatures (CTs). Subsequent research has indicated that the equiatomic ternary CoCrNi medium-entropy alloy (MEA), as a subset of the Cantor alloy family, has better mechanical properties than the CoCrFeMnNi alloy. Interestingly, both the strength and ductility of the CoCrNi MEA are higher at CTs than at room temperature. CoCrNi-based alloys have attracted considerable attention in the metallic materials community and it is therefore important to generalize and summarize the latest progress in CoCrNi-based MEA research. The present review initially briefly introduces the discovery of the CoCrNi MEA. Subsequently, its tensile response and deformation mechanisms are summarized. In particular, the effects of parameters, such as critical resolved shear stress, stacking fault energy and short-range ordering, on the deformation behavior are discussed in detail. The methods for strengthening the CoCrNi MEA are then reviewed and divided into two categories, namely, modifying microstructures and adjusting chemical compositions. In addition, the mechanical performance of CoCrNi-based MEAs, including their dynamic shear properties, creep behavior and fracture toughness, is also deliberated. Finally, the development prospects of CoCrNi-based MEAs are proposed.

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“…[ 4 ] The main difference between the HEAs and MEAs is in the configurational entropy

false(Δ S_{conf} false)

, which is defined as

Δ S_{conf} \geq 1.5

for HEAs and

1.0 \leq Δ S_{conf} \leq 1.5

for MEAs. [ 5 ] MEAs are also known for their excellent mechanical characteristics such as high strength and toughness, [ 6,7 ] thermal phase stability, [ 8 ] wear resistance, [ 9 ] and damage sustainability. [ 10 ] In some cases, MEAs, such as CoCrNi, have been reported to excel HEAs in terms of strength, ductility, and toughness.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Cold Spray Bonding for CrFeNi Medium‐Entropy Alloy

et al. 2022

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As a solid‐state deposition, cold spray maintains the intrinsic characteristics of the feedstock powder. Thus, it provides a unique opportunity for depositing high‐entropy alloys (HEAs) and medium‐entropy alloys (MEAs) that are of great interest for coatings to protect vulnerable materials from aggressive environments. However, considering the high hardness and the complexity of these powder's preparation, the choice of deposition parameters through experiments can be challenging and costly. Herein, a finite element model is presented to simulate the deposition of CrFeNi MEA using cold spray technology. A detailed approach is implemented to model the bonding of the particle to the substrate. The model is able to identify the deposition velocity window and simulate the metallurgical and mechanical interlocking. The particle adheres to the substrate at 500 m s−1 and pushes the substrate down facilitating mechanical interlocking. Furthermore, due to the strain localization induced by the particle, a notable temperature increase is observed at the substrate surface raising to its melting point in agreement with the ejecta eruption phenomenon. The developed numerical method can pave the way for successful experiments in case of costly HEAs and MEAs powders.

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Gradient recrystallization to improve strength and ductility of medium-entropy alloy

Cited by 15 publications

References 56 publications

Simultaneous Improvement of Yield Strength and Ductility at Cryogenic Temperature by Gradient Structure in 304 Stainless Steel

Simultaneous Improvement of Yield Strength and Ductility at Cryogenic Temperature by Gradient Structure in 304 Stainless Steel

A critical review of the mechanical properties of CoCrNi-based medium-entropy alloys

Numerical Simulation of Cold Spray Bonding for CrFeNi Medium‐Entropy Alloy

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