Modified deformation behaviour of self-ion irradiated tungsten: A combined nano-indentation, HR-EBSD and crystal plasticity study

Das, Suchandrima; Yu, Hongbing; Mizohata, Kenichiro; Tarleton, Edmund; Hofmann, Felix

doi:10.1016/j.ijplas.2020.102817

Cited by 37 publications

(18 citation statements)

References 109 publications

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“…Unfortunately, the direct comparison with the 20 MeV implanted sample cannot be easily made, since the micro-beam Laue diffraction technique used to study the 20 MeV sample lacks the spatial resolution required to resolve nano-scale strain heterogeneity. Previous mechanical property [38] and thermal transport studies [39], performed on 20 MeV self-ion implanted tungsten as a function of damage dose, suggest that there is little difference in the damage microstructure of 0.07 dpa and 0.1 dpa damaged tungsten.…”

Section: Ion Implantationmentioning

confidence: 94%

Nanoscale lattice strains in self-ion implanted tungsten

Phillips

Das

et al. 2020

Acta Materialia

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Developing a comprehensive understanding of the modification of material properties by neutron irradiation is important for the design of future fission and fusion power reactors. Self-ion implantation is commonly used to mimic neutron irradiation damage, however an interesting question concerns the effect of ion energy on the resulting damage structures. The reduction in the thickness of the implanted layer as the implantation energy is reduced results in the significant quandary: Does one attempt to match the primary knock-on atom energy produced during neutron irradiation or implant at a much higher energy, such that a thicker damage layer is produced? Here we address this question by measuring the full strain tensor for two ion implantation energies, 2 MeV and 20 MeV in self-ion implanted tungsten, a critical material for the first wall and divertor of fusion reactors. A comparison of 2 MeV and 20 MeV implanted samples is shown to result in similar lattice swelling. Multi-reflection Bragg coherent diffractive imaging (MBCDI) shows that implantation induced strain is in fact heterogeneous at the nanoscale, suggesting that there is a non-uniform distribution of defects, an observation that is not fully captured by micro-beam Laue diffraction. At the surface, MBCDI and high-resolution electron back-scattered diffraction (HR-EBSD) strain measurements agree quite well in terms of this clustering/non-uniformity of the strain distribution. However, MBCDI reveals that the heterogeneity at greater depths in the sample is much larger than at the surface. This combination of techniques provides a powerful 1

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Section: Ion Implantationmentioning

confidence: 94%

Nanoscale lattice strains in self-ion implanted tungsten

Phillips

Das

et al. 2020

Acta Materialia

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“…55 Deformation around spherical indents was altered, partially due to the swelling stress, and partially due to radiation defects. 17,18 Residual stress from radiation swelling in implanted SiC in this work, using a sharp indenter, causes a more significant change to deformation with the suppression of fracture; this effect should not be neglected when studying ion-implanted metals.…”

Section: Effect Of Ion Implantation On Plastic Deformation and Hardnessmentioning

confidence: 88%

“…Elastic and plastic deformation around nanoindents in unirradiated and helium-or self-ionirradiated tungsten has recently been investigated using high-angular-resolution electron backscatter diffraction (HR-EBSD), Laue diffraction, and crystal plasticity finite element modeling (CP-FEM), finding localization of dislocations and elastic strain near indent impressions after irradiation, and different pile-up characteristics. 17,18 To accurately replicate experimental results, the authors included biaxial compressive stress in the CP-FEM model to represent constrained lattice swelling, while they attribute most of the hardening and deformation changes to radiation defects.…”

Section: Introductionmentioning

confidence: 99%

Effect of Ion Irradiation on Nanoindentation Fracture and Deformation in Silicon Carbide

Leide

Todd

Armstrong

2021

JOM

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Silicon carbide is desirable for many nuclear applications, making it necessary to understand how it deforms after irradiation. Ion implantation combined with nanoindentation is commonly used to measure radiation-induced changes to mechanical properties; hardness and modulus can be calculated from load–displacement curves, and fracture toughness can be estimated from surface crack lengths. Further insight into indentation deformation and fracture is required to understand the observed changes to mechanical properties caused by irradiation. This paper investigates indentation deformation using high-resolution electron backscatter diffraction (HR-EBSD) and Raman spectroscopy. Significant differences exist after irradiation: fracture is suppressed by swelling-induced compressive residual stresses, and the plastically deformed region extends further from the indentation. During focused ion beam cross-sectioning, indentation cracks grow, and residual stresses are modified. The results clarify the mechanisms responsible for the modification of apparent hardness and apparent indentation toughness values caused by the compressive residual stresses in ion-implanted specimens.

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“…Raster scanning was utilised to obtain a spatially uniform implantation profile across the sample surface. Details of the implantation can be found elsewhere [56,57]. ECCI was performed on a Zeiss Crossbeam 540 SEM equipped with a backscattered electron (BSE) detector.…”

Section: Materials and Experimentsmentioning

confidence: 99%