Role of displacement cascades in Ni clustering in a ferritic Fe-3.3 at%Ni model alloy: Comparison of heavy and light particle irradiations

The behavior of solute atoms in an undersaturated Fe-3.3 at.%Ni model alloy upon heavy and light particle irradiations was investigated by Atom Probe Tomography. Whereas first irradiations, performed using 27 MeV Fe ions at 400 degrees C, highlight significant Ni enrichment on point defect clusters, solute-rich features detected after 2.8 MeV H+ ion (400 degrees C) and 1 MeV electron (320 degrees C) irradiations are only associated with pre-existent microstructural defects. Nanoindentation tests show no hardening in light particle irradiated samples, strongly suggesting that no dislocation loop formed. These observations put forward the importance of point defect clusters resulting from displacement cascades in Ni clusters' formation. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.