Chemical effects on He bubble superlattice formation in high entropy alloys

R. W. Harrison, G. Greaves, H. Le, H. Bei, Y. Zhang, S. E. Donnelly

Research output: Contribution to journalArticle

Abstract

The probable formation mechanism of He bubble superlattices relies on long range anisotropic diffusion of self-interstitial atoms (SIAs). Here we study He ion irradiation of pure Ni and two equiatomic concentrated solid-solution alloys (CSAs) of FeNi and FeCrNiCo. It is expected from the significantly reduced diffusion of SIAs in CSAs, including high entropy alloys (HEAs), that long range anisotropic SIA migration cannot be active. We report the formation of a He bubble lattice in pure Ni, and for the first time in FeNi and FeCrNiCo systems under 30 keV He ion irradiation at room temperature. The ion dose and flux required to form a bubble superlattice increase with chemical complexity. Comparing to Ni, SIA clusters change directions more frequently due to anisotropic elementally-biased diffusion from the higher degree of chemical non-homogeneity in CSAs. Nevertheless, anisotropic 1-D diffusion of interstitial defects is possible in these complex alloys over incrementally longer time scales and irradiation doses. The sluggish diffusion, characteristic in CSAs, leads to smaller superlattice parameters and smaller bubble diameters. The chemical biased SIA diffusion and its effects on He evolution revealed here have important implications on understanding and improving radiation tolerance over a wide range of extreme conditions.

LanguageEnglish
Number of pages8
JournalCurrent Opinion in Solid State and Materials Science
Early online date17 Jul 2019
DOIs
Publication statusE-pub ahead of print - 17 Jul 2019

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Bubble formation
Entropy
Solid solutions
Atoms
Ion bombardment
Dosimetry
Lead alloys
Superlattices
Irradiation
Ions
Fluxes
Radiation
Defects

Cite this

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title = "Chemical effects on He bubble superlattice formation in high entropy alloys",
abstract = "The probable formation mechanism of He bubble superlattices relies on long range anisotropic diffusion of self-interstitial atoms (SIAs). Here we study He ion irradiation of pure Ni and two equiatomic concentrated solid-solution alloys (CSAs) of FeNi and FeCrNiCo. It is expected from the significantly reduced diffusion of SIAs in CSAs, including high entropy alloys (HEAs), that long range anisotropic SIA migration cannot be active. We report the formation of a He bubble lattice in pure Ni, and for the first time in FeNi and FeCrNiCo systems under 30 keV He ion irradiation at room temperature. The ion dose and flux required to form a bubble superlattice increase with chemical complexity. Comparing to Ni, SIA clusters change directions more frequently due to anisotropic elementally-biased diffusion from the higher degree of chemical non-homogeneity in CSAs. Nevertheless, anisotropic 1-D diffusion of interstitial defects is possible in these complex alloys over incrementally longer time scales and irradiation doses. The sluggish diffusion, characteristic in CSAs, leads to smaller superlattice parameters and smaller bubble diameters. The chemical biased SIA diffusion and its effects on He evolution revealed here have important implications on understanding and improving radiation tolerance over a wide range of extreme conditions.",
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Chemical effects on He bubble superlattice formation in high entropy alloys. / Harrison, R. W.; Greaves, G.; Le, H.; Bei, H.; Zhang, Y.; Donnelly, S. E.

In: Current Opinion in Solid State and Materials Science, 17.07.2019.

Research output: Contribution to journalArticle

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