Stability of Helium Clusters during Displacement Cascades

Journal Article · Thu Feb 01 04:00:00 EST 2007 · Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 255(1 (SP ISS)):63-67

DOI:https://doi.org/10.1016/j.nimb.2006.11.064· OSTI ID:909475

Yang, Li; Zu, Xiaotao T; Xiao, H Y; Gao, Fei; Heinisch, Howard L; Kurtz, Richard J; Wang, Zhiguo; Liu, K Z

The interaction of displacement cascades with helium-vacancy clusters is investigated using molecular dynamics simulations. The He-vacancy clusters initially consist of 20 vacancies with a Helium-to-vacancy ratio ranging from 0.2 to 3. The primary knock-on atom (PKA) energy, Ep, varies from 2 keV to 10 keV, and the PKA direction is chosen such that a displacement cascade is able to directly interact with a helium-vacancy cluster. The simulation results show that the effect of displacement cascades on a helium-vacancy cluster strongly depends on both the helium-to-vacancy ratio and the PKA energy. For the same PKA energy, the size of helium-vacancy clusters increases with the He/V ratio, but for the same ratio, the cluster size changes more significantly with increasing PKA energy. It has been observed that the He-vacancy clusters can be dissolved when the He/V ratio less than 1, but they are able to re-nucleate during the thermal spike phase, forming small He-V nuclei. When the He/V ratio is larger than 1, the He-V clusters can absorb a number of vacancies produced by displacement cascades, forming larger He-V clusters. These results are discussed in terms of PKA energy, helium-to-vacancy ratio, number of vacancies produced by cascades, and mobility of helium atoms.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 909475
• Report Number(s): PNNL-SA-50941; AT6020100
• Journal Information: Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 255(1 (SP ISS)):63-67, Journal Name: Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 255(1 (SP ISS)):63-67 Journal Issue: 1 (SP ISS) Vol. 255
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ATOMIC DISPLACEMENTS
FE
Fe
HELIUM
He-vacancy cluster
KNOCK-ON
MD
MOLECULAR DYNAMICS METHOD
STABILITY
THERMAL SPIKES
VACANCIES
alpha-iron
displacement cascade
metals
molecular dynamics
simulation
stainless-steel
vacancy clusters