Temperature dependence of the Hall–Petch relationship in CoCrFeMnNi high-entropy alloy

Sun, Shijie; Tian, Yanzhong; Lin, Hao-Hsiung; Dong, Xianping; Wang, Y.H.; Wang, Z.J.; Zhang, Z.F.

doi:10.1016/j.jallcom.2019.07.357

Cited by 100 publications

(35 citation statements)

References 44 publications

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“…Similar to the results of Otto et al [18], Sun et al [19] found that σ 0 decreased rapidly from 436 MPa at 77 K to 188 MPa at 293 K, but then decreased more slowly to 119 MPa at 873 K. Their σ 0 values were always significantly greater than those determined by Otto et al [18] at all temperatures, see Tables 1 and 2, and Figure 3.…”

Section: Carbon Doping-cocrfemnnisupporting

confidence: 84%

“…Sun et al [19] also determined the Hall-Petch behavior of equiatomic single-phase f.c.c. CoCrFeMnNi from 77 to 873 K. The cast material was hot-forged and either annealed (to produce coarse-grained material) or cold-rolled and recrystallized (to produce fine-grained material).…”

Section: Carbon Doping-cocrfemnnimentioning

confidence: 99%

“…Sun et al [19] found that ε f decreased with increasing temperature for the two finer grain sizes e.g., from 41% at 77 K to 2% at 873 K for the 0.65 µm material, but for the coarsest-grained (105 µm) material ε f decreased from 82% at 77 K to~60% at 203 K after which it was constant up to 293-873 K. The coarser the grain size the greater the ε f value at all temperatures, e.g., at room temperature ε f was 27%, 33% and 60% for grain sizes of 0.65 µm, 2.1 µm and 105 µm, respectively. Sun et al [19] confirmed the earlier observations [18,22] that deformation occurs by a combination of dislocation motion and twinning at 77 K and 293 K. Twinning did not occur at higher temperatures, but dynamic recrystallization was observed at 873 K.…”

Section: Carbon Doping-cocrfemnnimentioning

confidence: 99%

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Interstitials in f.c.c. High Entropy Alloys

Baker

2020

Metals

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The effects of interstitials on the mechanical properties of single-phase f.c.c. high entropy alloys (HEAs) have been assessed based on a review of the literature. It is found that in nearly all studies, carbon increases the yield strength, in some cases by more than in traditional alloys. This suggests that carbon can be an excellent way to strengthen HEAs. This strength increase is related to the lattice expansion from the carbon. The effects on other mechanical behavior is mixed. Most studies show a slight reduction in ductility due to carbon, but a few show increases in ductility accompanying the yield strength increase. Similarly, some studies show little or modest increases in work-hardening rate (WHR) due to carbon, whereas a few show a substantial increase. These latter effects are due to changes in deformation mode. For both undoped and carbon doped CoCrFeMnNi, the room temperature ductility decreases slightly with decreasing grain size until ~2–5 µm, below which the ductility appears to decrease rapidly. The room temperature WHR also appears to decrease with decreasing grain size in both undoped and carbon-doped CoCrFeMnNi and in nitrogen-doped medium entropy alloy NiCoCr, and, at least for the undoped HEA, shows a sharp decrease at grain sizes <2 µm. Interestingly, carbon has been shown to almost double the Hall–Petch strengthening in CoCrFeMnNi, suggesting the segregation of carbon to the grain boundaries. There have been few studies on the effects of other interstitials such as boron, nitrogen and hydrogen. It is clear that more research is needed on interstitials both to understand their effects on mechanical properties and to optimize their use.

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Section: Carbon Doping-cocrfemnnisupporting

confidence: 84%

Section: Carbon Doping-cocrfemnnimentioning

confidence: 99%

Section: Carbon Doping-cocrfemnnimentioning

confidence: 99%

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Interstitials in f.c.c. High Entropy Alloys

Baker

2020

Metals

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“…However, the studies on the simultaneous addition of Mo, Nb, W and C into the CoCrFeNi-based HEAs were scarcely reported. Moreover, compared to the literature on the mechanical properties of the CoCrFeNi-based HEAs at room temperature, the studies on the high temperature properties are relatively less [10,[16][17][18][27][28][29][30][31]. The high temperature properties of the FCC-based HEAs were investigated in a different status, such as as-cast [26], rolled [27,28], different grain size [10,29,30] and multiple phases [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

“…The high temperature properties of the FCC-based HEAs were investigated in a different status, such as as-cast [26], rolled [27,28], different grain size [10,29,30] and multiple phases [16][17][18]. The ultrafine grain, rolled and multiple phases make the FCC-based HEAs possess higher room temperature mechanical properties (e.g., UTS is 995 MPa in Reference [30] and 1170 MPa in Reference [16]) but insufficient performances at elevated temperature, which the UTS is less than 600 MPa at 600 • C and basically less than 300 MPa at 800 • C. Therefore, the balance of the properties at room temperature and elevated temperature is in urgent need.…”

Section: Introductionmentioning

confidence: 99%

In Situ Development and High Temperature Features of CoCrFeNi-M6Cp High Entropy-Alloy Based Hardmetal

Lin

Liang

et al. 2020

Metals

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In this work, an in-situ CoCrFeNi-M6Cp high entropy-alloy (HEA) based hardmetal with a composition of Co25Cr21Fe18Ni23Mo7Nb3WC2 was fabricated by the powder metallurgy (PM) method. Microstructures and mechanical properties of this HEA were characterized and analyzed. The results exhibit that this HEA possesses a two-phase microstructure consisting of the face-centered cubic (FCC) matrix phase and the carbide M6C phase. This HEA has an average grain size of 2.2 μm, and the mean size and volume fraction of carbide particles are 1.2 μm and 20%. The tensile tests show that the alloy has a yield strength of 573 MPa, ultimate tensile strength of 895 MPa and elongation of 5.5% at room temperature. The contributions from different strengthening mechanisms in this HEA were calculated. The grain boundary strengthening is the dominant strengthening mechanism, and the carbide particles are significant for the further enhancement of yield strength by the dislocation strengthening and Orowan strengthening. In addition, with increasing temperatures from 600 °C to 900 °C, the HEA shows a reduced yield strength (YS) from 473 MPa to 142 MPa, a decreased ultimate tensile strength (UTS) from 741 MPa to 165 MPa and an enhanced elongation from 10.5% to 31%.

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Flow Behavior and Microstructure of Hot‐Worked TiNbTaVW Refractory High‐Entropy Alloy

Bamisaye,

Maledi,

Merwe

et al. 2024

Adv Eng Mater

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The high‐temperature deformation behavior of an equiatomic TiNbTaVW refractory high entropy alloy (RHEA) was studied at temperatures of 950, 1000, and 1050 °C and a strain rate of 10−3 s−1. The flow stress, high‐temperature strength, and softening mechanisms were analyzed and compared with the IN718 nickel‐based superalloy. The results indicate that the flow stress of both TiNbTaVW and IN718 is sensitive to deformation temperature, with high temperatures resulting in reduced flow stress. Globular grains and elongated grains were observed at 950 and 1000 °C for TiNbTaVW, signifying both dynamic recovery and dynamic globularization as the softening mechanisms. Globular grains were only observed at 1050 °C for TiNbTaVW, signifying dynamic globularization as the softening mechanism. The TiNbTaVW RHEA has a higher temperature strength of 910, 870, and 658 MPa compared to the IN718 alloy with 72, 87, and 61 MPa at 950–1000 °C/10−3 s−1. By demonstrating comparable or superior performance in specific aspects, RHEAs can be considered in the near future for potential applications traditionally dominated by nickel‐based superalloys.

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Temperature dependence of the Hall–Petch relationship in CoCrFeMnNi high-entropy alloy

Cited by 100 publications

References 44 publications

Interstitials in f.c.c. High Entropy Alloys

Interstitials in f.c.c. High Entropy Alloys

In Situ Development and High Temperature Features of CoCrFeNi-M6Cp High Entropy-Alloy Based Hardmetal

Flow Behavior and Microstructure of Hot‐Worked TiNbTaVW Refractory High‐Entropy Alloy

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