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Rapid Primary Radiation Damage Resistance Assessment of Precipitation-Hardened Cu Alloys

Elena Botica-Artalejo, Gregory Wallace, Michael P. Short

Abstract

This study establishes a direct correlation between in situ irradiation-induced property changes measured by transient grating spectroscopy (TGS) and the resulting microstructural damage in Cu-Cr-Ta alloys. Thin films fabricated by physical vapor deposition were irradiated with 6.6 MeV Cu +3 ions up to 25 DPA, while TGS continuously monitored the evolution of surface acoustic wave (SAW) frequency and thermal diffusivity. Post-irradiation transmission electron microscopy (TEM) was used to quantify void formation as a metric of accumulated radiation damage. A pronounced decrease in SAW frequency was observed some seconds after the onset of irradiation, and it was found to correlate strongly with the final void density. Vacancy MEB calculations propose that the small decrease in SAW frequency is associated with the low population of mobile vacancies, promoting defect recombination and decreasing void formation. This relationship enables early prediction of relative radiation damage resistance within minutes of irradiation, substantially reducing the time required compared to conventional irradiation and postcharacterization routes, allowing rapid screening of multiple compositions. We were able to test this method with 3 compositions of the Cu-Cr-Ta system. More generally, this in situ approach provides an efficient pathway for accelerating the development of materials for radiation environments.

Rapid Primary Radiation Damage Resistance Assessment of Precipitation-Hardened Cu Alloys

Abstract

This study establishes a direct correlation between in situ irradiation-induced property changes measured by transient grating spectroscopy (TGS) and the resulting microstructural damage in Cu-Cr-Ta alloys. Thin films fabricated by physical vapor deposition were irradiated with 6.6 MeV Cu +3 ions up to 25 DPA, while TGS continuously monitored the evolution of surface acoustic wave (SAW) frequency and thermal diffusivity. Post-irradiation transmission electron microscopy (TEM) was used to quantify void formation as a metric of accumulated radiation damage. A pronounced decrease in SAW frequency was observed some seconds after the onset of irradiation, and it was found to correlate strongly with the final void density. Vacancy MEB calculations propose that the small decrease in SAW frequency is associated with the low population of mobile vacancies, promoting defect recombination and decreasing void formation. This relationship enables early prediction of relative radiation damage resistance within minutes of irradiation, substantially reducing the time required compared to conventional irradiation and postcharacterization routes, allowing rapid screening of multiple compositions. We were able to test this method with 3 compositions of the Cu-Cr-Ta system. More generally, this in situ approach provides an efficient pathway for accelerating the development of materials for radiation environments.
Paper Structure (18 sections, 3 equations, 8 figures, 4 tables)

This paper contains 18 sections, 3 equations, 8 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Methods
  3. High-throughput material generation
  4. Microscopy characterization
  5. In situ ion irradiation coupled with transient grating spectroscopy
  6. CALPHAD calculations
  7. Nudge Elastic Band calculations
  8. Results
  9. Thermal conductivity calculations for Cu-based alloy systems
  10. TGS monitoring during self-ion irradiation
  11. Radiation damage assessment through transmission electron microscopy
  12. Statistics analysis of the vacancy migration energy barriers
  13. Discussion
  14. Alloy system selection
  15. Primary radiation damage resistance comparison
  16. ...and 3 more sections

Figures (8)

  • Figure 1: a)Combinatorial deposition of Cu-Cr-Ta alloys. b)Substrate holder with Si wafers after deposition.
  • Figure 2: Schematic of TGS coupled with in situ ion irradiation. Adapted from hofmann_transient_2019.
  • Figure 3: CALPHAD Thermal conductivity evaluation between different candidate elements in the 88 at.%Cu-8 at.%Cr-4at.%X system. TCHEA7 database was employed.
  • Figure 4: $I^3TGS$ results from the Cu–5 at.% Cr–2.5 at.% Ta sample irradiated at 6.5 MeV with Cu$^{3+}$ ions at $250^\circ C$. Blue dots correspond to SAW frequency values and orange dots to thermal diffusivity.
  • Figure 5: TEM images from the different Cu-Cr-Ta compositions. On the left side pictures were taken with an underfocus value of $-1\mu m$, and images on the right column were taken with an overfocus value of $+1\mu m$. Red arrows point out the voids.
  • ...and 3 more figures