Intrinsic factors responsible for brittle versus ductile nature of refractory high-entropy alloys

Intrinsic factors responsible for brittle versus ductile nature of refractory high-entropy alloys

Refractory high-entropy alloys (RHEAs) are of interest for ultrahigh-temperature applications. To overcome their drawbacks — low-temperature brittleness and poor creep strength at high temperatures — improved fundamental understanding is needed. Using experiments, theory, and modeling, we investigat...

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Published in:Nature communications Vol. 15; no. 1; p. 1706
Main Authors: Tsuru, Tomohito, Han, Shu, Matsuura, Shutaro, Chen, Zhenghao, Kishida, Kyosuke, Iobzenko, Ivan, Rao, Satish I., Woodward, Christopher, George, Easo P., Inui, Haruyuki
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 24-02-2024
Nature Publishing Group
Nature Portfolio
Subjects:
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147/135
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639/301/1023/1026
639/301/1023/303
Alloys
Compressibility
Creep strength
Ductile-brittle transition
Ductility
Entropy
High entropy alloys
High temperature
Humanities and Social Sciences
Low temperature
Mechanical properties
multidisciplinary
Science
Science (multidisciplinary)
Screw dislocations
Shear modulus
Slip planes
Temperature
Ultrahigh temperature
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Summary:Refractory high-entropy alloys (RHEAs) are of interest for ultrahigh-temperature applications. To overcome their drawbacks — low-temperature brittleness and poor creep strength at high temperatures — improved fundamental understanding is needed. Using experiments, theory, and modeling, we investigated prototypical body-centered cubic (BCC) RHEAs, TiZrHfNbTa and VNbMoTaW. The former is compressible to 77 K, whereas the latter is not below 298 K. Hexagonal close-packed (HCP) elements in TiZrHfNbTa lower its dislocation core energy, increase lattice distortion, and lower its shear modulus relative to VNbMoTaW whose elements are all BCC. Screw dislocations dominate TiZrHfNbTa plasticity, but equal numbers of edges and screws exist in VNbTaMoW. Dislocation cores are compact in VNbTaMoW and extended in TiZrHfNbTa, and different macroscopic slip planes are activated in the two RHEAs, which we attribute to the concentration of HCP elements. Our findings demonstrate how ductility and strength can be controlled through the ratio of HCP to BCC elements in RHEAs. Poor ductility is a major drawback of otherwise promising refractory high-entropy alloys (RHEAs) for ultrahigh temperature applications. Here, the authors show how ductility can be enhanced by adding HCP elements to BCC RHEAs, which is a relatively simple way to optimize mechanical properties.
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ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-024-45639-8