Microstructure and mechanical properties of the new Nb25Sc25Ti25Zr25 eutectic high entropy alloy

Rogal, Łukasz; Morgiel, J.; Świątek, Z.; Czerwiński, F.

doi:10.1016/j.msea.2015.10.071

Cited by 109 publications

(23 citation statements)

References 18 publications

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“…The alloy showed a compressive yield strength (σ 0.2 ) of 517 ± 7 MPa and compressive ultimate strength (σ UTS ) of 1863 ± 12 MPa, with a total compressive fracture strain of ~34%. These compressive properties are superior to the other eutectic compositions as well 14,25 . The compressive fracture surface is shown in Fig.…”

Section: Resultsmentioning

confidence: 81%

Small-scale mechanical behavior of a eutectic high entropy alloy

Muskeri

Hasannaeimi

Salloom

et al. 2020

Sci Rep

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eutectic high entropy alloys, with lamellar arrangement of solid solution phases, represent a new paradigm for simultaneously achieving high strength and ductility, thereby circumventing this wellknown trade-off in conventional alloys. However, dynamic strengthening mechanisms and phaseboundary interactions during external loading remain unclear for these eutectic systems. In this study, small-scale mechanical behavior was evaluated for Alcocrfeni 2.1 eutectic high entropy alloy, consisting of a lamellar arrangement of L1 2 and B2 solid-solution phases. The ultimate tensile strength was 1165 MPa with ductility of ~18% and ultimate compressive strength was 1863 MPa with a total compressive fracture strain of ~34%. Dual mode fracture was observed with ductile failure for L1 2 phase and brittle mode for B2 phase. Phase-specific mechanical tests using nano-indentation and micro-pillar compression showed higher hardness and strength and larger strain rate sensitivity for B2 compared with L1 2. Micro-pillars on B2 phase deformed by plastic barreling while L1 2 micro-pillars showed high density of slip steps due to activation of more slip systems and homogenous plastic flow. Mixed micropillars containing both the phases exhibited dual yielding behavior while the interface between L1 2 and B2 was well preserved without any sign of separation or cracking. Phase-specific friction analysis revealed higher coefficient of friction for B2 compared to L1 2. These results will pave the way for fundamental understanding of phase-specific contribution to bulk mechanical response of concentrated alloys and help in designing structural materials with high fracture toughness. Multi-principal element alloys (MPEAs), also known as high entropy alloys (HEAs), offer a new paradigm in structural alloy design and development owing to their appealing physical and mechanical properties such as high fracture toughness, good wear and fatigue resistance, high strength and good elevated temperature properties 1-3. Several HEA systems have been reported with a single-phase face center cubic (FCC) or body center cubic (BCC) structure 4-6. To concurrently achieve good ductility of FCC HEAs along with high strength of BCC HEAs, eutectic high entropy alloys (EHEAs) have recently been developed to overcome the limitations of single-phase HEAs 7. EHEAs typically consist of a mixture of two solid-solution phases in the form of lamellae or rod-like dispersions in a matrix. To date, several EHEAs have been reported with excellent combination of high strength and ductility including CoFeNi 1.

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Section: Resultsmentioning

confidence: 81%

Small-scale mechanical behavior of a eutectic high entropy alloy

Muskeri

Hasannaeimi

Salloom

et al. 2020

Sci Rep

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show abstract

“…Both the parameters as a whole have predicted the TCP phase formation without providing any guidance on the coexistence of FCC + TCP region. Therefore, we have surveyed a large number of literatures on EHEAs . The different physiochemical parameters used for the calculation are presented in Table .…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, the Co 2 Mo 0.8 Ni 2 VW 0.8 EHEA consisted of a mixture of FCC solid solution phase and µ phase exhibited the compression strength of 2364 MPa and a plastic strain of 14.4% . The quaternary Nb 25 Sc 25 Ti 25 Zr 25 EHEA with BCC and HCP lamella showed high compressive strength of 1250 MPa and low plasticity of 8.2% . Recently, a new CoCrFeNiMnPd EHEA was synthesized, where seaweed eutectic‐dendritic solidification pattern with alternate FCC and tetragonal lamellae has been observed .…”

Section: Introductionmentioning

confidence: 99%

Composition Dependence on the Evolution of Nanoeutectic in CoCrFeNiNb_x (0.45 ≤ x ≤ 0.65) High Entropy Alloys

Chanda

Das

2017

Adv Eng Mater

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The effect of Nb addition in arc-melted CoCrFeNiNb x (0.45 x 0.65) high entropy alloys (HEAs) on the phase evolution, stability, refinement of the microstructure, and mechanical properties are investigated. Minor fluctuation of Nb modifies the microstructure from hypoeutectic (x ¼ 0.45) to eutectic (x ¼ 0.5) and hypereutectic (x ¼ 0.55) containing 134-200 nm thin nanolamellar FCC γ-Ni and HCP Fe 2 Nb-type Laves phases. The nano-eutectic CoCrFeNiNb 0.5 HEA shows high yield strength (2060 AE 5 MPa) and strain hardening up to 2200 AE 10 MPa with 17.0 AE 0.5% compressive plasticity. Transmission electron microscopic studies of partially deformed specimen has been revealed that the activity of dislocations is present in the eutectic FCC/Laves lamellae and at their interface. The stability of the phases in CoCrFeNiNb x and other eutectic HEAs as reported in the literature, has been assessed by estimating mixing entropy (ΔS mix ), mixing enthalpy (ΔH mix ), atomic size differences (δ), valence electron concentration, Pauling electronegativity (Δχ P ), and Allen electronegativity (Δχ A ) to predict the evolution and coexistence of eutectic phases.

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“…6b; Table 3). The SAEDP from a similar area allowed the identification of the σ-phase with a tetragonal structure and zone axis [2][3][4][5][6][7][8][9][10][11] (Fig. 6d).…”

Section: Microstructure Analysis Of the Al20co20cr20fe20ni20 Heamentioning

confidence: 99%

“…There were examples of sets of four or more elements within groups from III to XII of the periodic table, which crystallized as simple solid solutions of BCC [1] or FCC structures [2]. Recent studies have led to the development of hexagonal close-packed (HCP) alloys [3,4] and new ones, such as high entropy alloys with eutectic mixtures [5], as well as composites reinforced with SiC [6] or Al 2 O 3 [7] based on the HEA matrix. Further studies focused on improvement of the mechanical properties of HEAs by applying various processing methods, like rapid cooling [8], thixoforming [9] or thermal or thermomechanical treatments [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Mechanical Properties of Al–Co–Cr–Fe–Ni Base High Entropy Alloys Obtained Using Powder Metallurgy

et al. 2019

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Four different compositions of high entropy alloys based on Al-Co-Cr-Fe and Al-Co-Cr-Fe-Ni systems were prepared using mechanical alloying and consolidation by spark plasma sintering. The chemical compositions of the studied alloys were experimentally selected to obtain a BCC solid solution and mixtures of BCC with FCC. The microstructure of the Al25Co25Cr25Fe25 (all in at%) high entropy alloy consisted of a matrix with a high concentration of Al, Co and Fe, in which spherical grains (50-200 nm) enriched in Cr were embedded. Both the matrix and grains had body centered cubic structures. The addition of nickel to a four-element system led to the formation of a multiphase composition. The microstructure of the Al20Co20Cr20Fe20Ni20, Al10Co30Cr20Fe35Ni5 and Al15Co30Cr15Fe40Ni5 HEAs consisted of fine grains measuring 50-500 nm composed of: AlNi-B2, BCC phase, FCC or BCC solid solutions and σ-sigma phase, respectively. The complex structure of the studied samples resulted in changeable mechanical properties. The highest compression strength of 3920 MPa was accompanied by an increased yield strength of 3500 MPa, and a low strain of 0.7%, for the Al25Co25Cr25Fe25 alloy. The addition of Ni led to the formation of plastic FCC phases responsible for a decrease in strength with increases in ductility, which, in the new non-equiatomic Al10Co30Cr20Fe35Ni5 high entropy alloy reached 6.3% at a yield strength of 1890 MPa and compression strength of 2230 MPa. The conducted abrasion studies revealed that non-equilibrium high entropy alloys have the highest abrasion resistance.

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Microstructure and mechanical properties of the new Nb25Sc25Ti25Zr25 eutectic high entropy alloy

Cited by 109 publications

References 18 publications

Small-scale mechanical behavior of a eutectic high entropy alloy

Small-scale mechanical behavior of a eutectic high entropy alloy

Composition Dependence on the Evolution of Nanoeutectic in CoCrFeNiNb_x (0.45 ≤ x ≤ 0.65) High Entropy Alloys

Microstructure and Mechanical Properties of Al–Co–Cr–Fe–Ni Base High Entropy Alloys Obtained Using Powder Metallurgy

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Microstructure and mechanical properties of the new Nb25Sc25Ti25Zr25 eutectic high entropy alloy

Cited by 109 publications

References 18 publications

Small-scale mechanical behavior of a eutectic high entropy alloy

Small-scale mechanical behavior of a eutectic high entropy alloy

Composition Dependence on the Evolution of Nanoeutectic in CoCrFeNiNbx (0.45 ≤ x ≤ 0.65) High Entropy Alloys

Microstructure and Mechanical Properties of Al–Co–Cr–Fe–Ni Base High Entropy Alloys Obtained Using Powder Metallurgy

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Composition Dependence on the Evolution of Nanoeutectic in CoCrFeNiNb_x (0.45 ≤ x ≤ 0.65) High Entropy Alloys