Microstructures and mechanical properties of ductile NbTaTiV refractory high entropy alloy prepared by powder metallurgy

Guo, Wenmin; Liu, Bin; Liu, Yong; Li, Tianchen; Fu, Ao; Fang, Qihong; Nie, Yan

doi:10.1016/j.jallcom.2018.10.230

Cited by 110 publications

(37 citation statements)

References 36 publications

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“…It is shown that the Al0.2 alloy had a yield strength of 783 MPa at 900 °C (specific yield strength was about 88.37 MPa*cm 3 /g). As can be seen from Figure 7 b, the high-temperature (<1000 °C) specific strength was better than that of the typical NbMoTaW RHEA [ 3 ], TaNbHfZrTi RHEA [ 26 ], NbTaTiV RHEA [ 11 ], Ni-based IN718 alloy, and Haynes 230 alloy [ 3 ]. This is because the single-phase BCC structure with multiple components and melting elements had slower element diffusion at higher temperatures [ 27 ].…”

Section: Resultsmentioning

confidence: 99%

“…Sheikh et al [ 10 ] reported a new RHEA (Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr) which achieved fracture strength of 1000 MPa and fracture plasticity of 20%. Guo et al [ 11 ] prepared a novel NbTaTiV RHEA through powder metallurgy (P/M) method, which has a yield strength of 1.37 GPa and a fracture strain of 23%. Unfortunately, although these RHEAs have high strength and acceptable plastic strain, their density is still too high, which hinders the practical application.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, choosing a refractory high-entropy alloy with both high strength and high plasticity as a matrix, and then reducing its density by adding light elements such as Al, is an effective method to obtain structural materials with high strength, low density, and good plasticity. The recently reported TaNbVTi alloy meets the requirements of the matrix very well [ 11 ]. Furthermore, Yang et al [ 15 ] reported that the arc-melted NbTiVTaAl 0.25 HEA has a low density of 8.78 g/cm 3 and reasonable plasticity greater than 50%.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the multicomponents in the RHEAs and the large differences in melting point, coarse dendrites and severe segregation are easily formed during the melting process, resulting in a multiphase structure with even several intermetallic phases [ 16 ]. Studies [ 6 , 7 , 11 , 16 , 17 ] have shown that a P/M method is one of the effective methods for preparing multicomponent RHEAs, which can avoid component segregation and obtain a uniform equiaxed crystal structure. The mechanical properties of these RHEAs are also expected to be further improved because the P/M technology uses a powder mixing method to make the composition uniform.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and Mechanical Properties of TaNbVTiAlx Refractory High-Entropy Alloys

Guo

Liu

et al. 2020

Entropy

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A series of TaNbVTiAlx (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) refractory high-entropy alloys (RHEAs) with high specific strength and reasonable plasticity were prepared using powder metallurgy (P/M) technology. This paper studied their microstructure and compression properties. The results show that all the TaNbVTiAlx RHEAs exhibited a single BCC solid solution microstructure with no elemental segregation. The P/M TaNbVTiAlx RHEAs showed excellent room-temperature specific strength (207.11 MPa*cm3/g) and high-temperature specific strength (88.37 MPa*cm3/g at 900 °C and 16.03 MPa*cm3/g at 1200 °C), with reasonable plasticity, suggesting that these RHEAs have potential to be applied at temperatures >1200 °C. The reasons for the excellent mechanical properties of P/M TaNbVTiAl0.2 RHEA were the uniform microstructure and solid solution strengthening effect.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microstructure and Mechanical Properties of TaNbVTiAlx Refractory High-Entropy Alloys

Guo

Liu

et al. 2020

Entropy

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“…In order to further identify the crystal structure of the P/M CoCrFeNiMo 0.2 HEA, we performed the TEM analysis on the precipitated phase. It is reported that the σ phase and μ phase in the CoCrFeNiMo x alloy systems is corresponding to the stoichiometric (Cr,Mo)(Co,Fe,Ni) and (Mo,Cr) 7 (Co,Fe,Ni) 6 respectively [ 26 , 27 ]. The EDS analysis results in Table 1 clearly indicates that the chemical composition of the precipitates contains a high concentration of Mo, which is very close to the σ phase reported by Shun et al [ 27 , 28 ].…”

Section: Resultsmentioning

confidence: 99%

Effects of Annealing on Microstructure and Mechanical Properties of Metastable Powder Metallurgy CoCrFeNiMo0.2 High Entropy Alloy

Zhang

Liu

et al. 2019

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A CoCrFeNiMo0.2 high entropy alloy (HEA) was prepared through powder metallurgy (P/M) process. The effects of annealing on microstructural evolution and mechanical properties of P/M HEAs were investigated. The results show that the P/M HEA exhibit a metastable FCC single-phase structure. Subsequently, annealing causes precipitation in the grains and at the grain boundaries simultaneously. As the temperature increases, the size of the precipitates grows, while the content of the precipitates tends to increase gradually first, and then decrease as the annealing temperature goes up to 1000 °C. As the annealing time is prolonged, the size and content of the precipitates gradually increases, eventually reaching a saturated stable value. The mechanical properties of the annealed alloys have a significant correspondence with the precipitation behavior. The larger the volume fraction and the size of the precipitates, the higher the strength and the lower the plasticity of the HEA. The CoCrFeNiMo0.2 high entropy alloy, which annealed at 800 °C for 72 h, exhibited the most excellent mechanical properties with the ultimate tensile strength of about 850 MPa and an elongation of about 30%. Nearly all of the annealed HEAs exhibit good strength–ductility combinations due to the significant precipitation enhancement and nanotwinning. The separation of the coarse precipitation phase and the matrix during the deformation process is the main reason for the formation of micropores. Formation of large volume fraction of micropores results in a decrease in the plasticity of the alloy.

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Phase Selection, Lattice Distortions, and Mechanical Properties in High‐Entropy Alloys

et al. 2020

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Increasing demand for improved physical, chemical, and mechanical properties led to the development of conventional alloys from single elements. These conventional alloys are made by selecting one or two major elements with desired properties, and other minor components are added to tune the properties to meet performance specifications. The conventional alloy design strategy is mainly based on the "solutesolvent" principle. However, another alloy design strategy based on multiprincipal elements in the near-equimolar ratio has recently been developed. In this multiprincipal element system, it is difficult to distinguish between the solute and the solvent, and various atoms are supposed to be randomly distributed in the crystal lattices (which has not been confirmed yet). This strategy, proposed by Yeh [1] and Cantor, [2] was based on the Boltzmann hypothesis of the relationship between entropy and system complexity. They proposed that the increased configurational entropy of mixing in alloys with multiple alloying elements in near-equiatomic proportions would overcome the enthalpy of compound formation, stabilizing solid solutions (SS) at the expense of intermetallics (IMs) during solidification. These multiprincipal element alloys are named "high entropy alloys" (HEAs), although the exact values of entropy in HEAs have not been experimentally measured yet. Since then, hundreds of HEAs with different combinations have been developed based on transition metals, refractory metals, and compound forming elements. [2-20] Most of these HEAs have been found to possess simple crystal structures such as the face-centered cubic (fcc) Fe-Co-Cr-Mn-Ni HEAs, [2] bodycentered cubic (bcc) Al-Co-Cr-Fe-Ni HEAs, [18] and the hexagonal close-pack (hcp) Ho-Dy-Y-Gd-Tb HEAs [6] when solidified from the melts. Experimental characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), nanoindentation, tensile, wear-and corrosionresistance tests have been used to study the microstructureproperties correlations of HEAs. [3-50] These studies have revealed that HEAs possess superior properties, such as high hardness and strength, [23-29] superior corrosion and wear resistance, [3,30-35] good magnetic properties, [9,36-39,51] structural stability, [7,40,41] attractive mechanical properties at extreme temperature conditions, [21,42-47] and good electronic properties. [48,49] Yeh [50] proposed four core effects of HEAs, namely: 1) high-entropy effect; 2) sluggish diffusion effect; 3) sever lattice distortion effect; and 4) cocktail effect, in which the lattice distortion might be the key factor affecting the properties of HEAs. Although a complete understanding of lattice distortions in HEAs is still not established yet, significant progress in HEAs has been made recently.

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Microstructures and mechanical properties of ductile NbTaTiV refractory high entropy alloy prepared by powder metallurgy

Cited by 110 publications

References 36 publications

Microstructure and Mechanical Properties of TaNbVTiAlx Refractory High-Entropy Alloys

Microstructure and Mechanical Properties of TaNbVTiAlx Refractory High-Entropy Alloys

Effects of Annealing on Microstructure and Mechanical Properties of Metastable Powder Metallurgy CoCrFeNiMo0.2 High Entropy Alloy

Phase Selection, Lattice Distortions, and Mechanical Properties in High‐Entropy Alloys

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