Nanoscale lattice strains in self-ion implanted tungsten

Abstract

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 method for detailed investigation of the microstructural damage caused by ion bombardment, and more generally of strain related phenomena in microvolumes that are inaccessible via any other technique.

arXiv commentPlease refer to the supplementary information and movies SM1-3 for data visualisation

References in corpus (8)

• High energy collision cascades in tungsten: dislocation loops structure and clustering scaling laws
• Elastic trapping of dislocation loops in cascades in ion-irradiated tungsten foils
• Effects of Irradiation Temperature and Dose Rate on the Mechanical Properties of Self-Ion Implanted Fe and Fe-Cr Alloys
• Energy spectra of primary knock-on atoms under neutron irradiation
• Modified deformation behaviour of self-ion irradiated tungsten: A combined nano-indentation, HR-EBSD and crystal plasticity study
• Nano-scale imaging of the full strain tensor of specific dislocations extracted from a bulk sample
• Helium-Implantation-Induced Lattice Strains and Defects in Tungsten probed by X-ray Micro-diffraction
• Mapping data between sample and detector conjugated spaces in Bragg coherent diffraction imaging

Cited by in corpus (6)

• Observation of transient and asymptotic driven structural states of tungsten exposed to irradiation
• Characterising Ion-Irradiated FeCr: Hardness, Thermal Diffusivity and Lattice Strain
• Non-destructive study of collision cascade damage in self-ion irradiated tungsten using HR-EBSD and ECCI
• Annealing of focused ion beam damage in gold microcrystals: An in situ Bragg coherent X-ray diffraction imaging study
• Refinements for Bragg coherent X-ray diffraction imaging: Electron backscatter diffraction alignment and strain field computation
• Low temperature state in strontium titanate microcrystals using in situ multi-reflection Bragg coherent X-ray diffraction imaging