Enhanced mechanical properties of HfMoTaTiZr and HfMoNbTaTiZr refractory high-entropy alloys

Juan, Chien-Chang; Tsai, Ming–Hung; Tsai, Che-Wei; Lin, Cheng‐Hsiung; Wang, Woei-Ren; Yang, Chih-Chao; Chen, Swe-Kai; Lin, Su-Jien; Yeh, Jien‐Wei

doi:10.1016/j.intermet.2015.03.013

Cited by 482 publications

(108 citation statements)

References 36 publications

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“…The density of the newly developed RHEA Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr was measured to be 8.13 g/cm 3 , which is comparable to those of current Ni-based superalloys, and also lower than those of previously reported RHEAs, such as MoNbTaVW (12.36 g/cm 3 ), 17 MoNbTaW (13.75 g/ cm 3 ), 17 HfNbTaTiZr (9.94 g/cm 3 ), 18 HfMoTaTiZr (10.24 g/ cm 3 ), and HfMoNbTaTiZr (9.97 g/cm 3 ). 20 With an estimated (by rule of mixture) melting point of 2055 C, Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr certainly has the potential to compete with Ni-based superalloys, if it also possesses decent hightemperature performance including high-temperature strength, resistance to creep deformation, and resistance to corrosion and oxidation. The high-temperature performance of Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr, and other low-density ductile RHEAs developed following the same alloy design strategy, will be the target for further studies.…”

Section: Resultsmentioning

confidence: 99%

“…However, the current bottleneck for utilizing RHEAs as structural materials is their general room temperature brittleness. [17][18][19][20][21] Interestingly, among the reported RHEAs, there exist two alloys that possess tensile ductility at room temperature: equiatomic quaternary HfNbTiZr 22 and equiatomic quinary HfNbTaTiZr. 23 The mechanism behind the ductility of HfNbTiZr and HfNbTaTiZr, in a sharp contrast to other brittle RHEAs, however, remains unknown.…”

Section: Introductionmentioning

confidence: 99%

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Alloy design for intrinsically ductile refractory high-entropy alloys

Sheikh

Shafeie

et al. 2016

Journal of Applied Physics

350

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Refractory high-entropy alloys (RHEAs), comprising group IV (Ti, Zr, Hf), V (V, Nb, Ta), and VI (Cr, Mo, W) refractory elements, can be potentially new generation high-temperature materials. However, most existing RHEAs lack room-temperature ductility, similar to conventional refractory metals and alloys. Here, we propose an alloy design strategy to intrinsically ductilize RHEAs based on the electron theory and more specifically to decrease the number of valence electrons through controlled alloying. A new ductile RHEA, Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr, was developed as a proof of concept, with a fracture stress of close to 1 GPa and an elongation of near 20%. The findings here will shed light on the development of ductile RHEAs for ultrahigh-temperature applications in aerospace and power-generation industries. Published by AIP Publishing.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Alloy design for intrinsically ductile refractory high-entropy alloys

Sheikh

Shafeie

et al. 2016

Journal of Applied Physics

350

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“…It shows the mean value of the computed magnitude of nearest-neighbor force constants of all pairs in the 5-component alloys versus the atomic masses. In addition to the already discussed NbTaTiVW and MoNbTaVW alloys, the HfMoTaTiZr alloy 38 has been included, motivated by recent interest 38 sparked by yield strengths comparable to current state-of-the-art superalloys. Note that the ternary HfNbZr sub-system is discussed in the Supplementary Information.…”

Section: Binarymentioning

confidence: 99%

Phonon broadening in high entropy alloys

et al. 2017

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Refractory high entropy alloys feature outstanding properties making them a promising materials class for next-generation hightemperature applications. At high temperatures, materials properties are strongly affected by lattice vibrations (phonons). Phonons critically influence thermal stability, thermodynamic and elastic properties, as well as thermal conductivity. In contrast to perfect crystals and ordered alloys, the inherently present mass and force constant fluctuations in multi-component random alloys (high entropy alloys) can induce significant phonon scattering and broadening. Despite their importance, phonon scattering and broadening have so far only scarcely been investigated for high entropy alloys. We tackle this challenge from a theoretical perspective and employ ab initio calculations to systematically study the impact of force constant and mass fluctuations on the phonon spectral functions of 12 body-centered cubic random alloys, from binaries up to 5-component high entropy alloys, addressing the key question of how chemical complexity impacts phonons. We find that it is crucial to include both mass and force constant fluctuations. If one or the other is neglected, qualitatively wrong results can be obtained such as artificial phonon band gaps. We analyze how the results obtained for the phonons translate into thermodynamically integrated quantities, specifically the vibrational entropy. Changes in the vibrational entropy with increasing the number of elements can be as large as changes in the configurational entropy and are thus important for phase stability considerations. The set of studied alloys includes MoTa, MoTaNb,

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“…These alloys are composed of refractory elements and are aimed for high temperature structural applications [40][41][42][43][44][45][46][47]. The primary phases in these alloys are generally BCC phase.…”

Section: Refractory Heasmentioning

confidence: 99%

“…Therefore, these alloys have great potential in high temperature applications. Many other refractory HEAs were developed later to obtain improved strength, room temperature ductility, and density [40,41,[47][48][49][50][51][52][53][54]. For example, Al addition in certain systems can bring advantages such as higher hardness and high-temperature strength, better room temperature plasticity, and lower density [48].…”

Section: Refractory Heasmentioning

confidence: 99%

Three Strategies for the Design of Advanced High-Entropy Alloys

Tsai

2016

Entropy

Self Cite

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High-entropy alloys (HEAs) have recently become a vibrant field of study in the metallic materials area. In the early years, the design of HEAs was more of an exploratory nature. The selection of compositions was somewhat arbitrary, and there was typically no specific goal to be achieved in the design. Very recently, however, the development of HEAs has gradually entered a different stage. Unlike the early alloys, HEAs developed nowadays are usually designed to meet clear goals, and have carefully chosen components, deliberately introduced multiple phases, and tailored microstructures. These alloys are referred to as advanced HEAs. In this paper, the progress in advanced HEAs is briefly reviewed. The design strategies for these materials are examined and are classified into three categories. Representative works in each category are presented. Finally, important issues and future directions in the development of advanced HEAs are pointed out and discussed.

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Enhanced mechanical properties of HfMoTaTiZr and HfMoNbTaTiZr refractory high-entropy alloys

Cited by 482 publications

References 36 publications

Alloy design for intrinsically ductile refractory high-entropy alloys

Alloy design for intrinsically ductile refractory high-entropy alloys

Phonon broadening in high entropy alloys

Three Strategies for the Design of Advanced High-Entropy Alloys

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