The temperature dependence of heavy-ion damage in iron: A microstructural transition at elevated temperatures

Abstract

A transition is reported in the dislocation microstructure of pure Fe produced by heavy-ion irradiation of thin foils, which took place between irradiation temperatures (T _irr) of 300°C and 500°C. At T _irr ≤ 400°C, the microstructure was dominated by round or irregular non-edge dislocation loops of interstitial nature and with Burgers vectors b = ½ ⟨111⟩, although interstitial ⟨100⟩ loops were also present; at 500°C only rectilinear pure-edge ⟨100⟩ loops occurred. At intermediate temperatures there was a gradual transition between the two types of microstructure. At temperatures just below 500°C, mobile ½⟨111⟩ loops were seen to be subsumed by sessile ⟨100⟩ loops. A possible explanation of these observations is given.

Keywords:

• radiation damage
• in situ electron microscopy
• defect analysis
• microstructural characterisation

Acknowledgements

We thank Dr A. Liu and P. Baldo of the Argonne National Laboratory for their help in using this facility. The IVEM-Tandem Facility (within the Electron Microscopy Center at ANL) is supported by the US DOE Office of Science and operated under contract no. DE-AC02-06CH11357 by UChicago Argonne, LLC. We are grateful to Dr S.L. Dudarev and Dr S.P. Fitzgerald for helpful discussions. We thank B. Miller, D. Graham, and Prof. I.M. Robertson (UIUC) for help with Video 4. Part of this work was funded by the UKAEA, Culham Science Centre.