Mechanical properties and deformation twinning behavior of as-cast CoCrFeMnNi high-entropy alloy at low and high temperatures

Kim, Jeoung Han; Lim, Ka Ram; Won, Jong Woo; Na, Young Sang; Kim, Hyoungseop

doi:10.1016/j.msea.2017.11.081

Cited by 115 publications

(25 citation statements)

References 27 publications

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“…Several HEAs have been shown to exhibit exceptional mechanical properties. For example, the CrMnFeCoNi Cantor alloy (2) demonstrates excellent mechanical properties at both room and cryogenic temperatures with the tensile strength up to ~1 GPa, ductility of ~60 to 70%, and fracture toughness exceeding ~200 MPa √ _ m (3)(4)(5)(6)(7). Such a superior combination of strength, ductility, and toughness, as promoted by decreasing temperature (8,9), stems from the synergy of several deformation mechanisms in the Cantor alloy, including dislocation slip and twinning at early stages (3,10,11) and crack bridging at late stages of deformation (12,13).…”

Section: Introductionmentioning

confidence: 99%

Deformation-induced crystalline-to-amorphous phase transformation in a CrMnFeCoNi high-entropy alloy

et al. 2021

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The Cantor high-entropy alloy (HEA) of CrMnFeCoNi is a solid solution with a face-centered cubic structure. While plastic deformation in this alloy is usually dominated by dislocation slip and deformation twinning, our in situ straining transmission electron microscopy (TEM) experiments reveal a crystalline-to-amorphous phase transformation in an ultrafine-grained Cantor alloy. We find that the crack-tip structural evolution involves a sequence of formation of the crystalline, lamellar, spotted, and amorphous patterns, which represent different proportions and organizations of the crystalline and amorphous phases. Such solid-state amorphization stems from both the high lattice friction and high grain boundary resistance to dislocation glide in ultrafine-grained microstructures. The resulting increase of crack-tip dislocation densities promotes the buildup of high stresses for triggering the crystalline-to-amorphous transformation. We also observe the formation of amorphous nanobridges in the crack wake. These amorphization processes dissipate strain energies, thereby providing effective toughening mechanisms for HEAs.

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Section: Introductionmentioning

confidence: 99%

Deformation-induced crystalline-to-amorphous phase transformation in a CrMnFeCoNi high-entropy alloy

et al. 2021

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“…In this work, the CoCrFeNi-based HEA added with all Mo, Nb, W and C shows a higher UTS due to the reinforcement of M 6 C. Figure 6b displays the profiles of the UTS of the FCC-based HEAs as a function of testing temperatures. The rolled CoCrFeNiMn HEAs [27,28] have higher UTS at room and elevated temperature than the as-cast CoCrFeNiMn HEA [26], and the fine microstructure with a different grain size also has a great impact on the performance of HEAs [10,29]. Jeong et al [31] reported the Fe 41 Mn 25 Ni 24 Co 8 Cr 2 HEA (FCC) with an ultrafine grain size (≤0.5 µm) exhibited outstanding UTS (995 MPa) at room temperature but the UTS sharply dropped (less than 200 MPa) above 700 • C due to coarse grains after recrystallization.…”

Section: Discussionmentioning

confidence: 99%

“…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%

“…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]. 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%

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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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“…During the last decade, the design and development of multicomponent materials called high-entropy alloys and high-entropy ceramics (HECs) with remarkable characteristics and applications have become more significant in the field of TBCs [25]. High-entropy materials have higher configurational entropy (∆S conf ) than conventional materials, promoting the formation of a single-phase solid solution, which leads to promising mechanical properties at elevated temperatures [26,27]. New research studies have revealed that formation of a single-phase solid solution in high-entropy materials is an effective method for enhancing the thermal properties of TBCs [28,29].…”

Section: Introductionmentioning

confidence: 99%

Interfacial Structure and Physical Properties of High-Entropy Oxide Coatings Prepared via Atmospheric Plasma Spraying

et al. 2021

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The feasibility of using a high-entropy rare-earth oxide (REO) as a top coating material for thermal barrier coatings was explored using the atmospheric plasma spray technique. The microstructure and Vickers hardness of the coating layer were compared to those of an 8 mol % yttria-stabilized zirconia (8YSZ) top coating material. Macroscopic observations revealed the formation of a well-coated surface with no surface defects or delamination. Scanning electron microscopy images showed the presence of several parallel and vertical microcracks in the REO and 8YSZ coating layers. The origin of these cracks is attributed to differences in the coefficient of thermal expansion, very fast cooling, and process parameters. X-ray diffraction demonstrated the high phase stability and excellent thermal properties of REO due to the absence of phase transformation after plasma spray processing. The measured Vickers hardness of REO was 425 HV, which is lower than that of sintered REO powder and the 8YSZ coating.

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Mechanical properties and deformation twinning behavior of as-cast CoCrFeMnNi high-entropy alloy at low and high temperatures

Cited by 115 publications

References 27 publications

Deformation-induced crystalline-to-amorphous phase transformation in a CrMnFeCoNi high-entropy alloy

Deformation-induced crystalline-to-amorphous phase transformation in a CrMnFeCoNi high-entropy alloy

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

Interfacial Structure and Physical Properties of High-Entropy Oxide Coatings Prepared via Atmospheric Plasma Spraying

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